HomeMy WebLinkAbout1995-143-10/17/1995-ADMINISTRATION FLOODPLAINS GUIDELINES MANAGEMENT STORMWATER UTILITY_ .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
RESOLUTION 95-143
OF THE COUNCIL OF THE CITY OF FORT COLLINS
APPROVING AND ADOPTING THE GUIDELINES FOR THE
MANAGEMENT AND ADMINISTRATION OF FLOODPLAINS
WHEREAS, the City of Fort Collins is vulnerable to floods on the Cache La Poudre River,
Spring Creek, Dry Creek, Fossil Creek, Boxelder Creek, Cooper Slough, dam failures, and urban
street flooding; and
WHEREAS, the City of Fort Collins has experienced the physical and emotional
consequences of loss of life and damage to property caused by flood disasters; and
WHEREAS, preparedness for emergencies and disasters requires the establishment of
farsighted and publicized public policy; and
WHEREAS, implementing sound floodplain management can reduce the loss of life and
property damage typically associated with flood disasters; and
WHEREAS, implementing sound floodplain management can also provide for a balance
between the protection of the environment and the economic development of floodplain lands; and
WHEREAS, the residents of the City of Fort Collins benefit from participating in the
National Flood Insurance Program and the Community Rating System; and
WHEREAS, the Storm Drainage Board has reviewed the proposed Guidelines for the
Management and Administration of Floodplains and has recommended to the City Council that the
same be adopted; and
WHEREAS, the residents of the City of Fort Collins will receive direct benefit from a
focussed Floodplain Management Program through reduced flood insurance premiums.
NOW,THEREFORE, BE IT RESOLVED BY THE COUNCIL OF THE CITY OF FORT
COLLINS as follows:
Section 1. That the attached GUIDELINES FOR THE MANAGEMENT AND
ADMINISTRATION OF FLOODPLAINS, CITY OF FORT COLLINS, COLORADO, dated
October 17, 1995, be and hereby are approved and adopted.
Section 2. That City staff shall perform an annual review of the Guidelines for the
Management and Administration of Floodplains and make any necessary administrative changes to
the text as new information becomes available in order to maintain the most current floodplain data
and policies for the City.
Passed and adopted at a regular meeting of the Counci e City of Fort lin held this
17th day of October, A.D. 1995.
Mayor
ATTEST: (\I
ML CIO z
City Clerk
GUIDELINES FOR THE
MANAGEMENT AND ADMINISTRATION
OF FLOODPLAINS
CITY OF FORT COLLINS
COLORADO
PART A: The City of Fort Collins Floodplain Management Program
PART B: The City of Fort Collins Floodplain Policy and Administration of
Floodplain Regulations
City of Fort Collins
Stormwater Utility
October 17, 1995
TABLE OF CONTENTS
MissionStatement....................................................................................3
Stormwater Utility Vision Statement..............................................................4
Acknowledgements...................................................................................5
PublicMeetings.......................................................................................5
Document Organization and Use...................................................................5
PART A; Floodplain Management Program
I. Background and Problem Identification...........................................................7
Community Description....................................................................7
Principle Flood Problems and History...................................................7
Cache La Poudre River............................................................7
SpringCreek.......................................................................I I
DryCreek..........................................................................12
FossilCreek........................................................................13
Boxelder Creek and Cooper Slough...........................................13
DamFailure........................................................................14
Urban Flash Flooding............................................................14
Flood Protection Measures...............................................................16
II. Floodplain Studies...................................................................................17
Purpose for Studying Floodplains.......................................................17
Flood Insurance Studies...................................................................17
City Master Drainageway Plans.........................................................18
Channel Stability Studies.................................................................23
III. Flood Hazard Inventory............................................................................25
Floodprone Buildings......................................................................25
Cache La Poudre Floodplain....................................................25
Spring Creek Floodplain.........................................................26
Dry Creek Floodplain............................................................27
Fossil Creek Floodplain..........................................................27
Boxelder Creek and Cooper Slough Floodplain............................27
Urban Floodplain and Stormwater Basin...................................28
Critical Facilities...........................................................................28
TABLE OF CONTENTS
MissionStatement....................................................................................3
Stormwater Utility Vision Statement..............................................................4
Acknowledgements...................................................................................5
PublicMeetings.......................—..........—....................... ------- ------------—....5
City Council Adoption...............................................................................5
Document Organization and Use...................................................................5
PART A; Floodplain Management Program
I. Background and Problem Identification...........................................................7
Community Description....................................................................7
Principle Flood Problems and History...................................................7
Cache La Poudre River............................................................7
SpringCreek.......................................................................11
DryCreek..........................................................................12
FossilCreek........................................................................13
Boxelder Creek and Cooper Slough...........................................13
DamFailure........................................................................14
Urban Flash Flooding............................................................14
Flood Protection Measures...............................................................16
II. Floodplain Studies...................................................................................17
Purpose for Studying Floodplains.......................................................17
Flood Insurance Studies...................................................................17
City Master Drainageway Plans.........................................................18
Channel Stability Studies.................................................................23
III. Flood Hazard Inventory............................................................................25
Floodprone Buildings......................................................................Z.�
Cache La Poudre Floodplain....................................................25
Spring Creek Floodplain.........................................................26
Dry Creek Floodplain............................................................27
Fossil Creek Floodplain..........................................................27
Boxelder Creek and Cooper Slough Floodplains............................27
Urban Floodplains and Stormwater Basins...................................28
Critical Facilities...........................................................................28
IV. Development Trends................................................................................31
Cache La Poudre River...................................................................31
DryCreek...................................................................................31
SpringCreek................................................................................32
FossilCreek.................................................................................32
Boxelder Creek and Cooper Slough....................................................33
V. Development Controls..............................................................................33
VI. Floodplain Areas that Provide Natural and Beneficial Functions...........................34
VII. Floodplain Management............................................................................35
Review of Possible Activities............................................................35
Coordination with Other Agencies......................................................39
Floodplain Management Activities and
the Community Rating System...........................................................39
VIR. Evaluation and Report..............................................................................57
PART B; Floodplain Policy and Administration of Floodplain Regulations
I. Definitions............................................................................................60
III. Objectives.............................................................................................67
IV. Benefits................................................................................................67
V. Floodplain Policy....................................................................................68
VI. National Flood Insurance Program...............................................................69
FloodInsurance.............................................................................69
The Galloway Report......................................................................70
VII. State of Colorado Floodplain Legislation.......................................................70
VIII. Comprehensive City Goals, Objectives, and Policies.........................................71
Goals and Objectives......................................................................72
Landuse Policies Plan.....................................................................73
Natural Areas Policy Plan................................................................74
Parks and Recreation Master Plan......................................................74
Framework for Environmental Action.................................................75
Poudre River Landuse Framework......................................................75
Watershed Approach.......................................................................76
DC. Floodpiahr Administrator's Power and Duties..................................................6
X. Administration of Floodplain Regulations......................................................78
XI. Considerations for Floodplain Use Permitting.................................................80
XII. Floodplain Compliance and Ordinance Enforcement.........................................84
XIII. Substantial Improvement Policy..................................................................85
LIST OF FIGURES
Figure1. Location Map.................................................................................8
Figure 2. Floodplains in Fort Collins................................................................9
Figure 3. Floodway-Floodplain Schematic.........................................................19
Figure 4. Fort Collins Stormwater Basin Map....................................................20
Figure 5. River and Creek Resource Areas........................................................37
LIST OF TABLES
Table 1. Natural and Beneficial Floodplain Functions..........................................36
Table 2. Strategies and Tools from the Unified National
Program for Floodplain Management..................................................38
Table 3. Open Space, Parks, and City Owned
Lands Located in Floodpiains............................................................47
Table-4. Area of Open Space, Parks, and
City Owned Lands Located in Floodplains............................................49
APPENDICES
Appendix-L- City- Of Fort-Collins-Code,-Section_M-Flood-Prevention-and Protection
'x
q4
"Fort Collins,the County seat and principal town in Larimer County, owes its origin and
first place on the map to the intervention of a flood in the Cache La Poudre River"
-Ansel Watrous (1911) refers to the flood of 1864
2
Mission Statement
Camp Collins was established on the banks of the Cache La Poudre River in 1862 as a military
outpost near the present site of the town of LaPorte, CO. In late June of 1864 a flood described as
the "worst known" by European settlers poured out of the banks of the Cache La Poudre River.
Lieutenant Colonel W.O. Collins described the site of the outpost as ground subject to overflow
[floodplain],the whole having been under water and much public property damage resulting.
Camp Collins was relocated in August of 1864 further downstream to higher ground, however,
was still located near the floodplain.
In June 1891 the Chambers Lake Reservoir Dam on the headwaters of the Cache La Poudre
River failed resulting in flooding of Fort Collins. Substantial public property damage occurred
including bridges, fences, headgates, buildings, cattle, and horses being swept into the flood
waters.
The flood of May 1904 was the greatest on the Cache La Poudre River. Over 150 houses were
swept from their foundations and all bridges but one were destroyed. A seven year old boy was
swept to his death trying to escape the flood waters on Dry Creek, a tributary of the Cache La
Poudre, which also flooded. Mr. Robert Strauss, who lived near the banks of the Poudre River
since 1859, also died in the floodwaters. Total damages in Larimer County alone were nearly
$150,000 from the 1904 flood.
Regionally, two of the most devastating floods in Colorado history occurred near Fort Collins. In
August 1976 a devastating flood swept through the nearby Big Thompson Canyon, about 15
miles south of the Cache La Poudre Canyon,_causing-139 deaths, 5 missing persons, and more
than$35 millions dollars in total damages. Substantial flood damages to structures and property
also occurred downstream of the canyon mouth near Loveland, CO, 10 miles south of Fort
Collins. In 1982 the Lawn Lake Dam near Estes Park, CO., located 30 miles southwest of Fort
Collins in the mountains, failed causing 3 deaths and$31 millions dollars in damages.
in 1983, the Cache La Poudre threatened flooding from rapicIsnowmelt Ur tire-mountains:
Although-severe-flooding did riot_occar the-rivetrpmained_above_flood stage for 45 days and the
Governor declared a state of emergency. Damage did occur in a number of areas from channel
bank erosion and meander migration near the Environmental Learning Center. The bike trail, a
dike along Mulberry Street, Countryside Mobile Home Park,the Cache La Poudre Elementary
School and Junior High School, and the Fort Collins Waste Water treatment Plant No. 2 were all
threatened by the snowmelt runoff flooding.
The spring of 1995 was also a year for high runoff associated with snowmelt. Although the
Cache La Poudre remained for the most part within its banks, except for bike trail flooding and
some bank erosion, three teenagers had to be rescued from the river and crop damages east of
Fort Collins was in the millions of dollars. The river was at its highest since 1983. In addition,
the Burlington Northern Railroad embankment failed near the I-25 crossing as a result of gravel
pit capture of the floodwaters.
Fort Collins,typical of towns located along the Front Range of the Rocky Mountains, is subject
to potentially devastating floods. The Cache La Poudre River and its tributaries, and dam
failures associated with Horsetooth Reservoir and water storage reservoirs located far upstream
at the headwaters of the Cache La Poudre River, are the primary flood hazards.
Fort Collins has not had a large magnitude flood in over 90 years. Since this time,the population
has increased from 1,376 residents in 1880 to nearly 100,000 in 1995. The number of people and
structures located in the floodplain hasalso increased.
In order to reduce the potential loss of life and personal property, the City of Fort Collins
Stormwater Utility Floodplain Management Program was established. By utilizing a variety of
management tools such as outreach projects to increase public awareness of the hazard and flood
protection measures, establishing local policy and ordinances to regulate floodplain development,
adopting design criteria for structures located in the floodplain, flood preparedness and warning
activities, acquisition of floodplain land, providing informational services such as map
determinations for property buyers and sellers, drainage system maintenance, and maintaining
the most up-to-date scientific information available on the local flood and erosion hazards, the
potential for loss of life and property is substantially reduced.
It is the responsibility of the City of Fort Collins Floodplain Management Program to manage
floodplains to promote the public health, safety and general welfare and to minimize public and
private losses due to flood conditions. It is also the responsibility of the floodplain management
program to provide for the highest quality of life possible to the residents of Fort Collins with
regard to management of the City's floodplains as a natural resource.
Stormwater Utility Vision Statement
The Stormwater Utility staff developed a"Vision Statement" with regard to; 1)the overall vision
and direction of the Stormwater Utility for the future; 2)the steps and resources required to get
there, and; 3) the expected standard of services provided to the City residents. The portion
pertaining to the floodplain management vision states:
"Our focused floodplain administration exceeds the federal standards, and
optimizes our ability to meet City Goals by recognizing and managing the
floodplain to balance the environment and economic development. Our residents
benefit from our nationally recognized CRS program and our staff trained in
emergency flood response."
These management guidelines were prepared with the intent of the Stormwater Utility vision in
mind.
4
Acknowledgements
This document was prepared by the Floodplain Division of the Stormwater Utility. The editorial
assistance and overall guidance of the Stormwater Utility Staff is gratefully acknowledged. In
addition, we extend our gratitude to the City Council and the Storm Drainage Board for their
guidance in the adoption and implementation of this plan. We thank the citizens of Fort Collins
for their input during the public comment period.
We would also like to thank the following departments for their review and helpful comments;
Natural Resources Division, Parks and Recreation Department, Advanced Planning
Department, Water and Waste Water Utility, Light and Power, Engineering Department,
Transportation Department, Police Services, Larimer County Engineering Department,
Colorado Water Conservation Board, the ISO Commercial Risk Services and the
Community Rating System.
Public Meetings and Outreach
The Storm Drainage Board recommended adoption of this plan at the October 5, 1995 meeting.
A Pubic Open House was held on September 28, 1995.
A mailing was sent to all floodplain residents in the City on September 22, 1995.
Newspaper advertisements were published on September 17 and 24, 1995.
Document Organization and Use
This document consists of two parts; Part A documents the current and ongoing floodplain
management program and activities in the City, and; Part B includes the policy, administrative,
and regulatory framework for the management of floodplains in the City of Fort Collins.
It is intended that each part can be used independently,however,both parts are written to
complement one another and provide a logical progression with regard to the overall floodplain
management program in Fort Collins. In addition,the guidelines are intended to include all
relevant information and provide the documentation and justification for all management
activities and regulatory decisions with regard to floodplain administration.
5
PART A
CITY OF FORT COLLINS
FLOODPLAIN MANAGEMENT PLAN
6
I. BACKGROUND AND PROBLEM IDENTIFICATION
Community Description
Fort Collins is located along the banks of the Cache La Poudre River in eastern Larimer County,
where the foothills of the Rockies meet the Great Plains, at an elevation of 4,979 feet above sea
level. Fort Collins is located approximately 60 miles north of Denver(Figure 1). The climate is
semi-arid with approximately 300 days of sunshine and an average annual precipitation of 14.5
inches. Winters are moderately cold and dry with an average January temperature of 27 degrees
Fahrenheit and 30 percent humidity. The average July temperature is 71 degrees with 43 percent
humidity.
Fort Collins-became incorporated-in-1137Tand hasgrown rapidly, from approximately 1,376
residents in 1880 to approximately 56,800 in 1975, to a current(1995) estimate of 99,726. Fort
Collins is at the northern edge of the rapidly growing Front Range of the Colorado Rocky
Mountains. The City currently covers approximately 44 square miles of area.
Principal Flood Problems and History
Fort Collins is vulnerable to flooding from several different sources (Figure 2). Flood sources
include; 1) the rivers and streams in Fort Collins which include the Cache La Poudre River,
Spring Creek, Dry Creek, Fossil Creek, Cooper Slough, and Boxelder Creek; 2) potential dam
failure; and, 3) urban flash flooding from intense rainfall on smaller drainage basins. The main
cause of floods in the Fort Collins area is intense rainfall, which normally occurs in the period of
May through September. The Cache La Poudre River flooding could also increase in May and
June, as a result of increased runoff from snowmelt.
Fort Collins has a long association with flooding. Ansel Watrous (1911), referring to the flood of
1864, stated that "Fort Collins, the county seat and principal town in Larimer County, owes its
origin and first place on the map to the intervention of a flood in the Cache La Poudre River."
Cache La Poudre River
The Cache La Poudre River is a major left bank tributary of the South Platte River. It joins the
South Platte about 5 miles east of Greeley, Colorado. The Poudre River originates within Rocky
Mountain National Park at an elevation close to 12,000 feet above mean sea level; then it flows
successively northward, eastward, and southeastward to its confluence with the South Platte
River at an elevation of about 4,600 feet above mean sea level (m.s.l). The drainage area at its
mouth is 1,890 square miles. The drainage area of the Poudre River above Fort Collins is
approximately 1,129 square miles.
Notable floods occurred on the Cache La Poudre River in 1844, 1864, 1884, 1891, 1904, 1923,
and 1930. The three largest floods occurred in 1864, 1891, and 1904, with flood peaks of
7
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Fort Collins Floodplains
Floodplain boundaries are approximate. Floodplains are the shaded areas.
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Figure 2. Floodplains in Fort Collins
approximately 21,000 cubic feet per second (cfs). The measurement of these large floods was by
indirect methods since the gage was washed out and is, therefore, only a best estimate.
The earliest flood account, described by Ansel Watrous of the flood of 1864, describes the flood
as the "worst known by white men and that the water poured out of the banks of the stream and
inundated the valley from bluff to bluff with a torrent that carried everything not firmly attached
to the soil with it. On reaching the plains,the water spread out and submerged the bottom lands
from bluff to bluff to a depth of several feet."
The 1904 flood probably did the greatest financial damage. During this flood, approximately
150 houses were swept away, and all the bridges were destroyed except one. It should be noted,
however, that the bridges and houses were not built to the same design standards as today. The
flood of May, 1904, was the greatest on the Cache La Poudre River for which definite evidence
is available. A newspaper account stated that the first warning of danger that people had was
when a "wall of water 10 to 14 feet high burst out of the Poudre Canyon a couple of miles above
La Porte." Nearly $150,000 in damage occurred within Larimer County.
Mr. Robert Strauss, a much respected resident who had lived near the bank of the Poudre River
since 1859, drowned in the 1904 flood. In addition, a seven-year old boy was swept to his death
when Dry Creek, a tributary of the Poudre, flooded during the same event.
Local resident accounts regarding the relative magnitude of the flood of 1904 and that of 1864 is
conflicting. One report stated that people living in the valley since 1859 reported that the flood of
1904 was about 1.5 feet higher than the flood of 1864. Another long time resident reported that
the flood of 1904 was greatly exceeded by the of 1864 and that, although the channel was wider
and carried more water in 1864 than in 1904, the flood of 1864 reached a higher point on his
property.
Most floods on the Cache La Poudre River in the plains area of the basin have caused damage to
crops, livestock, farm improvements, machinery, irrigation structures, and road and railroad
structures. Only the largest floods have caused damage to residential, commercial, and industrial
property in Fort Collins_
The record of past flood damages on the Poudre River does not accurately represent the current
flood threat to Fort Collins. A severe flood has not occurred in almost 90 years. The largest
floods since 1930 occurred in 1938, 1951, 1983, and 1995.
The peak of the 1938 flood approximately 6180 cfs. A newspaper account of the flood of 1951
stated that it was estimated by the district water commissioner to be about 8,000 cfs at Fort
Collins, however, the actual measurement at the mouth of the canyon was 5,600 cfs.
Newspaper accounts from 1961 also described heavy rainfall and flooding that cause the washout
of a portion of the roadbed under the Colorado and Southern Railroad track about 150 yards east
10
of Lincoln Avenue. Above average rainfall occurred throughout July and August of 1961 causing
localized flooding in various parts of town. Discharge estimates were not available.
In 1983,the Cache La Poudre threatened flooding from rapid snowmelt in the mountains.
Although severe flooding did not occur, the river remained above flood stage for 45 days and the
Governor declared a state of emergency. The flood peak occurred on June 21, at 6,660 cfs.
Damage did occur in a number of areas from channel bank erosion and meander migration
including a gravel pit capture near the Environmental Learning-Center. The-bike hail, a dike
along Mulberry Street, Countryside Mobile Home Park,the Cache La Poudre Elementary School
and Junior High School, and the Fort Collins Waste Water treatment Plant No. 2 were all
threatened by the snowmelt runoff flooding.
The spring of 1995 was also a year for high runoff associated with snowmelt. Although the
Cache La Poudre remained for the most part within its banks in town, except for bike trail
flooding and some bank erosion,three teenagers had to be rescued from the river and crop
damages east of Fort Collins was in the millions of dollars. In addition,the Burlington Northern
Railroad embankment failed near the 1-25 crossing as a result of gravel pit capture of the
floodwaters. The flood peak occurred on June 18 at 4,690 cfs.
The flood hydrology of the Cache La Poudre River is primarily controlled by spring snowmelt
runoff, which produces annual flood peaks with magnitudes generally less than the 10-year event
(about 6000 cfs). Larger floods are generally associated with runoff from summer
thunderstorms. Rainfall on snow can produce the largest floods. The river contains a number of
flood hazard areas, from the narrow canyons in the mountainous west to the wide floodplain in
the east. Due to the rapidly growing population, the flood hazard is constantly changing.
The Colorado State University Earth Resources Department is currently gathering data on the
paleoflood history of the Cache La Poudre River Canyon. Flood slackwater deposits, which are
fine-grained sediments which settle from suspension in areas of reduced flow during floods, have
been found high above the current stream level in the Poudre Canyon. Flood sediments indicate
multiple peak discharges during the last 6,500 years. Some of these discharge values are
significantly larger than the highest gaged discharges at the canyon mouth gaging station, which
has been in operation since 1882. The peak discharge during this time period of record was
21,000 cfs, in June 1891.
Spring Creek
Spring Creek,which is a right bank tributary to the Cache La Poudre River, flows from west to
east through Fort Collins. Beginning at Spring Canyon Dam and Horsetooth Reservoir, Spring
Creek flows easterly until it joins the Cache La Poudre River near the intersection of Timberline
Road and Prospect Road. The Spring Creek basin has a drainage area of 30 square miles. The
upper 18 square miles of the basin is controlled by Spring and Dixon Canyon Dams and
Horsetooth Reservoir, which were constructed by the Bureau of Reclamation in 1954. Below the
11
dam, Spring Creek drainage basin's 12 square miles of uncontrolled area has a mean basin
elevation of about 5050 feet, m.s.l. Downstream of Horsetooth Reservoir, Spring Creek has an
average channel slope of about 52 feet per mile.
Floods occurred on Spring Creek in 1902, 1904, 1938, 1949, and 1951 prior to the completion of
Horsetooth Reservoir. The Horsetooth Reservoir was completed in the early 1950's and has
helped reduce-flooding problems-b-y reducing the_drainage area. The most recent floods
occurred in 1975 and 1977, causing flooding in several basements, and again in 1983 when a
storm sewer which carries Spring Creek under a mobile home park surcharged, and water ponded
to a depth of several feet. Property damage was in the $5,000 to $10,000 range.
In 1992,the City of Fort Collins completed a series of channel and floodplain improvements
along Spring Creek for flood protection and recreation. The multiple projects removed a number
of properties from the flood hazard area and created a public trail system for recreation.
Dry Creek
Dry Creek is a left bank tributary of the Cache La Poudre River. Dry Creek flows south through
the northeast portion of Fort Collins before joining the Cache La Poudre River south of Fort
Collins Airpark. The basin is about 23 miles long and 3 to 3.5 miles wide and has a drainage area
of about 65 square miles. Basin elevations range from 6960 feet, m.s.l. near its headwaters to
4910 feet, m.s.l. near its mouth.
In the upper portion of the basin, the stream is steep, narrow, and deeply incised with active
headcutting. Lower in the basin,the Dry Creek channel is relatively stable with wide, shallow
floodplains except below the Larimer and Weld Canal in Fort Collins, where the channel does
not exist in several areas. Upstream from the Alta Vista Community, the Dry Creek channel is
undefined except for a small drainage ditch just downstream from College Avenue. Extensive
commercial and residential development is located within the Dry Creek floodplain from College
Avenue to the Larimer and Weld Canal. Downstream from the Larimer and Weld Canal, the Dry
Creek channel has been obliterated from Willox Lane to downstream from the trailer court. In the-
Fort Collins Airpark,the disposal of building material and other fill in the Dry Creek channel has
reduced its capacity.
Dry Creek has not had serious flooding below the Eaton Ditch since the early 1950's. This
absence of even minor flooding is generally attributed to the network of irrigation canals that
have some capacity for intercepting small to moderate Dry Creek flows. Flood history prior to
this time period is unclear. Before substantial development occurred in the area, flows could
often be ignored where little damage was incurred.
The flood of 1904 is documented in a newspaper account which stated that the Water Supply and
Storage company got a lot of water from Dry Creek, storing in the Rocky Ridge reservoir at the
rate of nearly 500 feet per second. One death from the 1904 flood is documented, John
12
Parkinson,-a-7-year-oldboy,-drowned.-The family lived near the Eaton Ditch, which overflowed
above their house after they had gone to bed.
Flooding did occur in 1924 with flows several feet deep in the vicinity of Jax Surplus. It is
unclear as to whether this was actually due to overflows from the Poudre River.
Presently,the impact of new development in the lower basin of Dry Creek is already increasing
the magnitude and frequency of drainage flows. In the past, much of the excess drainage was
intercepted by irrigation canals. Today, these canals no longer have the capacity to intercept
larger flood flows and increased drainage flows. The irrigation canals should be bypassed with
proper conveyance provided in the drainageway.
Fossil Creek
Fossil Creek is a right bank tributary of the Cache La Poudre River. It flows from east to west
through Fort Collins into Fossil Creek Reservoir. The drainage area of Fossil Creek is
approximately 21 square miles above Fossil Creek Reservoir. The Fossil Creek channel is
generally incised and characterized by bed and bank instability and meander migration and
channel cutoffs. Fossil Creekchannel-characteristics-and-stability studies-are-discussed-in-the-
"Channel Stability Studies" section below.
The Fossil Creek basin is relatively undeveloped and floods in the past have gone unnoticed
except for some of the access roads to subdivisions which create ponding and road overtopping.
There is no gaging station in the basin. Local newspaper and resident accounts describe flood
events occurring in 1902, 1938, 1965, 1977, and 1979, however, very little detail on flooding in
Fossil Creek is available.
A newspaper account of the September 24, 1902 flood stated that,"between 4:20 p.m. Saturday
night and 5:20 p.m. Sunday night, Fossil Creek Reservoir gage reading indicated a fourteen foot
rise which amounts to 44,000,000 cubic feet of water in about 24 hours (an average of over
12,000 cubic feet per second). During Sunday night Fossil Creek continued to add to this body of
water at the rate of 500 cubic feet per second and Monday morning found the reservoir nineteen
feet deep."
Boxelder Creek and Cooper Sough
Boxelder Creek is a left bank tributary of the Cache La Poudre River. It flows from north to
south, beginning at its headwaters in southern Wyoming at an elevation of 7720 feet, m.s.l. and
ending at its confluence with the Cache La Poudre River at an elevation of 4860 feet, m.s.l. The
Boxelder Creek drainage basin covers an area of 25-1 square miles in Wyoming and Colorado.
The basin is about 32 miles long and 8 miles wide. Boxelder Creek flows along the northeast
edge of Fort Collins and joins the Cache La Poudre River south of Drake Road.
13
Boxelder Creek has a long history of flooding. Floods of record occurred in 1904, 1909, 1922,
1930, 1933, 1937, 1947, 1961, 1963, 1965, 1967, and 1969. There is no official gaging station in
the watershed and no known flows have been measured.
The flood of 1904 is documented in a newspaper account which stated that"in the Boxelder
Valley near Wellington there was a cloudburst and Coal Creek,Indian Creek, and the Boxelder
went into a rampage, flooding a good deal of land in the lower part of the valley. A.L. Clark's
farm was pretty much under and he had 200 chickens drowned. The North Poudre Company
claims to have caught 600 million feet in the Douglas, Clark, and Indian Creek reservoirs,the
latter being completely filled; it had just been completed. In Fort Collins little damage was done.
A good many cellars were filled, and Linden Street at the foot of College Avenue and at Walnut
was like a lake."
Another newspaper account of the 1904 flood stated that "the Boxelder, a small stream ordinarily
only a few feet wide, was tearing down through a fertile valley filled from bluff to bluff with a
sheet of water a mile wide, carrying buildings and bridges away in its mad rush."
The flood of June 1961 is documented in newspaper accounts. The estimated discharge for the
1961 flood was 500 cfs.
In general, information on past floods is based on newspaper accounts and interviews with
residents of the area. Out of the total drainage area of 251 square miles, approximately 176
square miles of the basin are controlled by Soil Conservation Service's flood control dams B-2,
B-4, B-5, and B-6 near Wellington, Colorado, which is about 8 miles upstream from Fort
Collins.
Boxelder Creek has four tributaries. They are Sand Creek, Rawhide Creek, Indian Creek, and
Cooper Slough. Cooper Slough flows on the eastern edge of Fort Collins and crosses Colorado
State Highway 14 just east of the Interstate. There is no available documented history of flooding
on these tributaries.
Dam Failure
Dam failure poses another threat to Fort Collins. Larimer County has 45 Class I (high hazard)
and 42 Class II (moderate hazard) dams,more than any other county in the state of Colorado.
Horsetooth Reservoir, with its four dams located just west of the city is the closest potential
hazard. One of the largest historic floods on the Poudre River that occurred on June 9, 1891, had
a peak discharge of 21,000 cfs associated with the failure of the Chambers Lake Dam.
Urban Flash Flooding
Urban flash flooding is a flood hazard in Fort Collins. Major historic rainfall events (year of
occurrence in parentheses) in Fort Collins include 1.71"(1899), 6.22"(1902), 4.03(1904),
14
2.82"(1918), 2.70"(1933), 4.88"(1938), 3.72"(1949), 2.95"(1951), 6.06"(1951), 2.45"(1961),
2.41"(1965), 4.3"(1977), 1.4"(1983), 1.52"(1988), 2.49"(1992). Documentation with regard to
storm characteristics and flood damages is limited for these historic storms and obtained through
newspaper reports. Recent storms that have resulted in property damage and localized urban
flooding are better documented, however.
The storm of 1902 is documented as.flooding the CSU campus. The rainfall resulted in ten feet
of water in the heating plant, flooding the gymnasium and field house, and five feet of water in
the physics building basement.
The storm of 1933 is documented in a newspaper account which states that the measurement
reported at the Colorado Agricultural College Experiment Station indicate that the rainfall just
east of Fort Collins was considerably heavier than the 2.7 inches measurement at the weather
bureau of the college. At the beet station,the precipitation measured 4.24 inches and at the
experiment station, 3.7 inches.
The storm of 1938 is documented in newspaper accounts which stated "that residents along the
No. 2 ditch at the west city limits of Fort Collins spent an anxious night as water lapped over the
ditch edge. Many of those in the neighborhood turned out to help divert overflowing water into
Mountain Avenue and Oak Street where the water ran into sewer openings at each corner as far
east as Shields Street." A basement apartment flooded at 416 Locust Street. It was reported that
all basements in houses on the 800 block of Whedbee Street were flooded, as were basements in
the 500 block on Pitkin Street.
The storm of 1951 put an estimated 400 telephones, mostly on the north edge of Fort Collins, out
of service. Power lines were also out around town for the day. The east, west, and south walls of
an old brick building of the Strang Grain Company in the 100 block on North Mason street
collapsed, apparently after the rain washed away the crumbling sections at the bottom of the
walls. Water running in at the south ramp of the county hospital covered the first floor hallway
and several wards to a depth of about one inch. About 28,000 envelopes were destroyed at the
Fort Collins Post Office postal stock. Flooding at Plum and Locust streets caused numerous
basements to be flooded. Flooding of basements in homes on LaPorte Avenue was also reported.
Approximately $270,000 damage occurred to Colorado A&M Campus (CSU) from overflowing
irrigation ditches west of campus. The water reportedly ran down the same channel which carried
a damaging flood 13 years ago (1938 storm). The gymnasium, student union, physics and
electrical engineering building,power plant, heating tunnels, and library were all flooded.
The July 25 1977 storm caused localized urban flooding of streets and buildings. In a report to
City Council the storm was described as moderate intensity over several days. The peak rainfall
for a 24-hour period during the storm was 4.3 inches. The storm appeared to be concentrated
over the southeast portion of the city.
15
The June 3, 1985 storm resulted in 1.4 inches of rain in 1 hour and 1.46 inches over a 24 hour
period. The June 3 storm consisted of an intense afternoon thunderstorm typical along the Front
Range.
The May 18, 1988 storm was characterized by rainfall occurring over a larger area and a longer
duration than a typical afternoon thunderstorm. The storm began on the afternoon of May 18,
1988 and continued for two days until the morning of May 20, 1988. The first rain on the
afternoon of May 18 was the most intense with 0.45 inches recorded during the first hour on the
CSU campus. The storm was generally more widespread with 1.20 inches of rain occurring on
the CSU campus, and 0.98 to 1.52 inches of rain reported by Mountain States Weather Service
spotters in the Fort Collins area.
The storm of July 7, 1988 was the most significant storm to occur since 1985 in the downtown
area. Although only 0.53 inches (1 hour rainfall) was recorded during the storm at Colorado State
University (CSU), the northern part of the city received significantly more rainfall. In the Old
Town area on Loomis Street just north of Mulberry Street and Whitcomb Street just south of
Mountain Avenue, approximately 1 inch of rain was reported.North of Fort Collins near Country
Club Road and North Lemay Avenue 1.5 to 2 inches were measured.
The storm of August 4, 1988 is documented by local resident rain gages and Mountain States
Weather with 1 to 1 1/2 inches in about 30 minutes. There are reports of limited residential
flooding associated with this storm.
The June 24, 1992 storm, estimated to be a 20 year event, ranks as the third heaviest rainfall in
Fort Collins history. The record of 2.49 inches was taken at the city's official weather station on
the Colorado State University campus. However, 3.09 inches of rain was recorded in the
northwestern part of the city.
The majority of June 24, 1992 rainfall occurred in 30 minutes. Storm sewers, unable to handle
the volume of water, caused many streets to flood. Several businesses and private residences
sustained flood damage, mainly to basement levels. The flooding affected the older section of
town the worst, a combination of that area receiving the most rainfall and having an out-dated
storm drainage system. The total damage was $438,000. About 50 homeowners reported flooded
basements in the Old Town area. Flooding of Poudre Valley Hospital occurred because roof
drains were unable to handle the volume of water on the roof.
Flood Protection Measures
There are no flood control structures on the Cache La Poudre River in Fort Collins, although
there are two irrigation dams on the North Fork of the Cache La Poudre River. The effects of the
two dams are considered negligible in Fort Collins.
16
The Spring Creek basin does not have any flood control structures below Horsetooth Reservoir.
The City of Fort Collins has, however, channelized portions of the Spring Creek channel, and
improved culverts and bridges in order to reduce the flood hazard and remove people and
property from the floodplain.
Dry Creek-has-several'Lakes and storage-reservoirs which reduce-the-contributing drainage-area
by approximately 13 percent, although they are not really flood control structures. Douglas
Lake, located outside Fort Collins corporate limits is also an irrigation reservoir that provides
about 15%-20%flood flow attenuation for the 100-year event.
Boxelder Creek has approximately 75% of its contributing drainage basin controlled by Soil
Conservation Service (SCS) Flood Control reservoirs near Wellington. The SCS flood control
reservoirs have substantially reduced the flood peaks in the vicinity of Fort Collins.
Fossil Creek drains from the edge of the foothills through Fort Collins and into Fossil Creek
Reservoir. There are no flood control structures upstream of Fossil Creek Reservoir.
II. FLOODPLAIN STUDIES
Purpose of Studying Floodplains
1. To minimize the loss to life and property.
2. To develop and disseminate the most accurate information obtainable on flooding.
3. To educate the public to the hazards of flooding.
4. To determine actuarial rates for flood insurance.
5. To provide flood prone communities, such as Fort Collins, with information necessary to
implement floodplain management measures.
Flood Insurance Studies
In 1979 the Federal Emergency Management Agency (FEMA)published the Flood Insurance
Study (FIS) for the City of Fort Collins, Larimer County, Colorado. The purpose of the FIS was
to investigate the existence and severity of flood hazards in the City of Fort Collins and to aid in
the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection
Act of 1973. Initial use of the information was to convert the City of Fort Collins to the regular
program of flood insurance by the FEMA. Further use of the information is made by the City to
promote sound land use and floodplain development.
17
Community base map selection and the identification of streams requiring detailed study was
done by Larimer County Planning Department, Federal Insurance Administration(FIA), U.S.
Army Corps of Engineers (ACOE), Colorado Water Conservation Board, and the study
contractor. The source of authority for the FIS is the National Flood Insurance Act of 1968. The
work was completed in 1977, and revised in 1984 and in 1995.
Floods caused by overflow of Spring Creek, Dry Creek, and the Cache La Poudre River were
studied in detail. The revised studies included detailed studies of the Cooper Slough,Boxelder
Creek, and revisions to the Cache La Poudre River and Spring Creek. Floodplain administration
standards for all floodplains within the City comply with the minimum standards of the NFIP,
however, in general, exceed the NFIP standards as discussed below with regard to floodway
regulation.
Hydrologic analyses were carried out to establish the peak discharge-frequency relationships for
floods of the selected recurrence intervals for existing conditions for each stream studied in detail
in the community. Analyses of the hydraulic characteristics of existing conditions of streams
were carried out to provide estimates of the elevations of floods of the selected recurrence
intervals along each stream studied in the community.
Results can be found in the City of Fort Collins, Colorado, Revised 1995 FIS Report by FEMA
and on the published Flood Insurance Rate Maps (FIRM) Community (080102) Panels. In
addition, areas of the City that have been annexed since the effective date of the published FIRM
can be found on the Latimer County, Colorado (unincorporated areas) FIRM panels.
In order to provide a national standard without regional discrimination, the 100-year flood (Zone
AE) has been adopted by the Federal Insurance Administration as the base flood for purposes of
floodplain management measures. The 500-year flood(Zone X) is employed to indicate
additional areas of flood risk in the community. Figure 3 depicts the adopted definitions of the
floodplain, floodway, and flood fringe.
The City of Fort Collins has a floodway criteria which exceeds the minimum standards of the 1.0
foot rise established by the FIA. The City of Fort Collins limits increases in flood heights to 0.5
foot for all water courses except Dry Creek, which complies with the maximum 1.0 foot rise FIA
standard.
City Master Drainageway Plans
The City of Fort Collins has adopted a stormwater basin map(Figure 4)which delineates the
boundaries of the stormwater basins in the City and in areas which may be annexed. The map
serves as official designation of the respective stormwater basins of the City. Each stormwater
basin has a Master Drainage Plan officially adopted by the City, as well as the State and County.
Information contained in the master plans is used in the administration of City floodplain
activities.
18
100-YEAR FLOOD PLAIN --
FLOODWAY FLOODWAY
FRINGE FLOODWAY FRINGE
STREAM
CHANNEL
FLOOD ELEVATION WHEN
CONFINED WITHIN FLOOOWAY
ENCROACHMENT ENCROACHMENT
77
........... SURCHARGE' }:::::::::::•:C
A :WX
AREA OF FLOOD PLAIN THAT COULD FLOOD ELEVATION
BE USED FOR DEVELOPMENT BY BEFOREENCROACHMENT
RAISING GROUND ON FLOOD PLAIN
LINE AB IS THE FLOOD ELEVATION BEFORE ENCROACHMENT.
LINE CO IS THE FLOOD ELEVATION AFTER ENCROACHMENT.
'SURCHARGE IS NOT TO EXCEED 1.0 FOOT OR LESSER AMOUNT IF SPECIFIED BY STATE.
Figure 3. Floodway-Floodplain Schematic
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Jys :
a .y 33
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i<
dt,i
a •�■�r��j7, k�e en ael t 1®' aNq a
•cif bb ��d d
R
• ems` al
Floodplains identified in the Master Drainageway Plans, in addition to those identified by FEMA
as federal regulatory floodplains, are administered to comply with or exceed the minimum
standards of the NFIP. Master Drainageway Plans include floodway determination using the 0.5
foot criteria, except Dry Creek which uses 1.0 foot criteria, and 100-year floodplain delineation
using developed basin hydrology conditions. The Fossil Creek Master Drainageway Plan
assumes that the floodway is equal to the floodplain as a result of the incised nature of the stream
and includes channel stability analyses.
Master Drainageway Plan floodplain delineation is based on a fully developed basin so are
generally more conservative than the FEMA delineation. Therefore,Master Drainageway Plans
are used to regulate proposed development in the floodplain. The FEMA Flood Insurance
Studies are used in conjunction with the Master Plans for the determination of compliance with
the NFIP flood insurance purchase requirements for FEMA floodplains (Cache La Poudre River,
Spring Creek, Dry Creek). However, for the purposes of floodplain administration in general,
whichever study map is more restrictive, FIRM or Master Drainage Plan,has precedence.
Master Drainageway Plans present floodplain information for major drainageways in the City
and include preliminary design of drainage improvement facilities to eliminate or alleviate flood
hazard along the drainageway. Master plans are used by local officials in planning the use and
regulation of floodplain areas such that flood hazards and future damages are eliminated or
minimized.
The Master Drainageway Plans contain information on historic floods, existing factors which
influence the flood hazard, and the nature and extent of probable future floods. Maps delineating
the flooded areas for the 100-year, and in some studies the 500-year, flood boundaries, flood
profiles, floodplain cross-sections, and floodway identification are included.
The objectives of the Master Drainageway Plans are:
1. To reduce the threat to human life, personal injury, or related health hazards due to
floods.
2. To reduce or prevent flood damage and maintenance requirements for public and private
property and facilities.
3. To provide sound technical basis for the management of floodplains by structural or
nonstructural methods.
4. To make effective use of public funds and to enhance and protect the value of land and
property.
5. To formulate and evaluate alternative flood control and drainage concepts and to
determine the most economically feasible and practical plan for mitigating flooding.
21
6. Delineation of flood hazard area.
Master Drainage Plans are as follows. Please note that there have been a number of site specific
studies associated with developments, and reaches that have been updated,that have modified
some of the Master Plans and provided more site specific information. The modified studies are
kept on file at the Stormwater Utility Office .
1. McCleilands and Mail Creek Major Drainageway Plan, prepared by Cornell Consulting
Company and John S. Griffith, P.E., dated December 1980.
2. Foothills Drainage Basin Drainage Master Plan,prepared by Resource Consultants, Inc.,
dated February 1981.
3: Fox Meadows Basin Drainage-Master PIan;prepared by Resource-Consultants, Inc:,
dated February 1981.
4. Dry Creek Drainageway Planning,prepared by Gingery Associates, Inc., dated January
1980.
5. Evergreen Park Basin Major Storm Drainage Study, prepared by Engineering
Professionals, Inc., dated February 1981.
6. Drainage Study of the Greenbriar Outfall Drainage Basin, prepared by Engineering
Professionals, Inc., dated April 1980.
7. West Vine Drainage Basin Major Drainageway Plan, prepared by Engineering
Professionals, Inc., dated December 1980.
8. Diversion of Stormwater Runoff through Irrigation Canals from Mulberry Street to
Spring Creek,prepared by Resource Consultants, Inc., dated July 1980.
9. Spring Creek Master Drainageway Plan,prepared by Engineering Professionals, Inc.,
dated March 1988.
10. Fossil Creek Drainage Basin Master Drainageway Planning Study, prepared by Simons,
Li,_ancLAssociates,_dated August_19g2.-
11. Old Town Master Drainageway plan, prepared by Resources Consultants and Engineers,
Ins., dated January 7, 1993.
12. Cooper Slough and Boxelder Creek Master Drainageway Planning Study,prepared by
Simons, Li, and Associates, Inc., dated August 1981. Not officially adopted.
22
13. Cooper Slough Implementation Plan, prepared by Simons, Li, and Associates, dated
October 1987. Not officially adopted.
14. Cache La Poudre River Master Drainageway Plan,prepared by Resource Consultants
Inc., in review.
Channel Stability Studies
In addition to overbank flooding and 100-year floodplain delineation,the Stormwater
Department has conducted studies on channel stability and delineation of erosion buffer zones
along certain channels. In particular, the Fossil Creek basin has a number of supplemental studies
to the Master Drainageway Plan.
Fossil Creek is generally incised into valley fill and/or bedrock and is characterized by steep
banks, a compound channel, meandering plan form, general vertical and/or lateral instability, and
a highly variable discharge regime. Although the Cache La Poudre, Spring Creek, and other
streams in Fort Collins may also have channel stability problems, the instability is usually
limited to a certain reach(es) of stream and may be associated with man-made structures or
channel modifications. Channel instability associated with Fossil Creek is generally inherent in
the system,however, the response of the system may be altered as a result of increased
stormwater and sediment runoff associated with development
Fossil Creek, like other rivers in semi-arid environments and the Plains-Piedmont of Colorado,
has different structures for temporal and spatial change than rivers such as the Cache La Poudre.
The concept of a system operating in a manner that establishes and maintains an equilibrium
condition usually takes the form of a presumed balance among hydraulic forces, material
resistances, and morphology of the fluvial system. The maintenance of an equilibrium condition
is-facilitated-by the nearly-continuous operationof streamflows in rivers such asthe-Cache-La-
Poudre.
Because Fossil Creek is characterized by a highly variable discharge regime,the long-term
tendency toward equilibrium may be disrupted. The wide fluctuations in discharge that can occur
over short periods of time imply that fluvial systems, such as Fossil Creek, cannot operate on a
continuous basis and that trends toward a process-form equilibrium are unlikely completed. The
radical short-term variations in discharge result in a system operation that is pseudocatastrophic
in that very large discharges drastically alter the channel morphology to a new configuration
suited to high flow, but that is not in equilibrium with subsequent low flows. The resulting
compound channel(low-flow pilot channel nested in a larger channel) may have two entirely
different behavior patterns depending on the discharge conditions, with intermediate discharges
causing damage through erosion even though overbank flow does not occur.
23
The result is that such a river will accomplish radical adjustment to extreme events by complete
changes of channel configuration. Such radical channel changes may substantially affect
development well outside the delineated 100-year floodplain. For this reason, "erosion buffer
limits" were established to protect man-made structures from the instability of the river system
and to minimize the influence of man's activities on the acceleration of the channel response.
The following reports include channel stability analyses and erosion buffer limits;
1. Final Report, Fossil Creek Stability Study, Trilby Road to Lemay Avenue, prepared by
Lidstone and Anderson, Inc., dated October 1992.
2. Mail Creek Stability Study,prepared by Lidstone and Anderson, Inc., dated January
1993.
3. Final Report for Stanton Creek Stability Study, prepared by Lidstone and Anderson, Inc.,
dated May 1993.
4. Channel Stability Analysis, Burns Creek and Fossil Creek, Clarendon Hills Development
in Fort Collins, dated September 1991.
5. Fossil Creek Drainage Basin Master Drainageway Planning Study, prepared by Simons,
Li, and Associates, dated August 1982.
6. Cache La Poudre River Master Drainageway Plan, prepared by Resource Consultants
Inc., in review.
7. Fossil Creek Stability Study - Huntington Hills P.U.D.- Lemay Avenue to College
Avenue, Lidstone and Anderson, Inc. In review.
The purpose of the Fossil Creek Basin stability studies are to; 1) characterize the stability of the
respective streams based upon an evaluation of hydrologic, hydraulic, geomorphic and sediment-
transport characteristics of the stream basin and develop practical improvements for mitigating
adverse impacts on the streams; 2) develop design criteria and construction standards for
improvements in natural drainageways,with regard to reach stability, within the City of Fort
Collins; and, 3) establish erosion buffer limits along the study reaches.
The Poudre River Master Plan also addresses channel stability along the Poudre River. The
stability analysis was conducted to determine the overall condition of the main river channel and
identify erosional or depositional trends that may adversely affect properties within and adjacent
to the 100-year floodplain. The results of the analysis indicate that the existing channel is
relatively stable vertically,but exhibits a strong tendency for lateral migration by erosion of the
channel banks. The field-inventory conducted by RCE Inc. (1994), indicates that approximately
40 percent of the total length of the main channel banks are either actively eroding or have been
protected from erosion using riprap, concrete rubble, or other techniques.
24
In spite of the historical degradation, further downcutting of the Poudre River channel under
existing conditions is considered to be unlikely due to the presence of the bedrock outcrop and
diversion weirs throughout the reach. The existence of numerous gravel pits along the banks of
the Poudre,however, may accentuate lateral channel instability by capture of the river by the
gravel pits. The Poudre River Master Plan identifies specific locations of channel stability
problems.
III. FLOOD HAZARD INVENTORY
Floodprone Buildings
Under natural conditions, a flood causes little or no damage. Nature ensures that floodplain flora
and fauna can survive the more frequent inundations. Flood problems exist when human
development encroaches into the floodplain and is subsequently damaged by nature's flood
waters. The City of Fort Collins is a rapidly growing community, and therefore, the flood hazard
is constantly changing.
The City has approximately 797 commercial and residential structures in the federally regulated
(NFIP) floodplains of the Cache La Poudre, Spring Creek, Dry Creek, Cooper Slough, and
Boxelder Creek. There are 191 flood insurance policies currently (1995) in effect. Some
structures are-at higher risk than others with regard to loss of property and life: The following
section describes and inventories the flood hazard in Fort Collins. The Master Drainageway
Plans should be referred to for detailed information on recommended improvement plans and
estimated costs for the respective stormwater basins and floodplains.
Cache La Poudre Floodplain
The Poudre River has the largest drainage area of the streams in Fort Collins, 1,129 square miles
above Fort Collins, and therefore, the largest relative flood potential. There are approximately
2,880 acres within the 100-year floodplain between Interstate 25 to Taft Hill Road which
encompasses the Urban Growth Area(UGA). There are approximately 1,279 acres within the
City limits.
There are approximately 220 structures in the Poudre River Floodplain between Interstate 25 and
Taft Hill Road(Poudre River Master Plan) which includes some buildings located in the County
jurisdiction. An inventory of all properties within the 100-year floodplain,prepared by Resource
Consultants and Engineers, Inc. (1995), is based on records obtained from the County Assessor's
office. The inventory was prepared by first performing a data base inquiry of the Assessor's
records using general descriptions of the 100-year floodplain boundaries based on the 1" = 600'
scale orthophoto mapping. The inquiry resulted in a listing of all properties within and adjacent
to the floodplain. This listing was then refined to identify those parcels that actually fell within
the floodplain boundaries delineated on quarter section plat maps. The Master Plan estimates $6
million of property damage that may occur along the Poudre River during the 100-year flood.
25
The Poudre River Master Plan identifies the largest value of damage occurring in the following
locations:
a. The Western Mobile property just downstream of Taft Hill Road. Property is in
Larimer County outside of City limits.
b. Business along North College Avenue. This area also overlaps with the Dry Creek
floodplain.
C. Wastewater Treatment Plant#1 near Riverside Avenue and Highway 14.
d. Countryside Estates near Riverbend Ponds. Outside City Limits in Larimer
County.
e. The Vipont property just downstream of Prospect Street near Prospect Ponds.
f. Businesses near Harmony Road and I-25
The Poudre River Master Plan recommends different improvement alternatives for the various
properties along the river reaches. Four possible approaches are suggested including the
advantages and disadvantages of each. The four approaches include; 1)no action, 2) structural
emphasis, 3) floodproofing emphasis, and 4) non-structural emphasis. Because of the complexity
of the Poudre River system, one approach may not be possible throughout the entire river
through Fort Collins, therefore, a reach by reach approach is taken in the Master Plan.
The construction of the North College Avenue bridge (1994-95) included the acquisition and
relocation/demolition of 3 structures. Only 2 of the structures are in the revised floodplain and
were acquired and relocated by the Ft. Collins Housing Authority.
Spring Creek Floodplain
Spring Creek has approximately 34 structures in the floodplain. Following recent (1983-1993)
channel, culvert, and bridge improvements and a revised FIS (1995), a substantial number of
structures have been removed from the regulatory floodplain.
The estimate of the number of structures in the Spring Creek floodplain is based on the aerial
photos and floodplain delineation in the revised FIS (1995). Since the aerial photos were taken
at different times between 1983 and 1993, the structure count is only a best estimate. An
additional number of structures may also be subject to shallow flooding, delineated as Zone X,
along Spring Creek resulting from localized flooding and backwater conditions outside the
regulatory floodplain.
Detailed property damage dollar estimates for the Spring Creek floodplain have not been done,
however, the recent improvements along the channel have substantially reduced estimated losses,
26
including the acquisition and relocation/demolition of approximately 37 structures that were
located in the floodplain. In addition, according to the revised FIS floodplain delineation,the
channel and floodplain improvements along Spring Creek has resulted in the removal of
approximately 49 structures from the regulatory floodplain as described above. In total,
approximately 86 structures have been removed from the regulatory floodplain.
Dry Creek Floodplain
There are currently (1995) 542 commercial and residential structures in the Dry Creek 100-year
floodplain within the City limits. Of the 542 structures,there are approximately 101 commercial
and 441 residential structures. In addition,there are 675 residential and 254 commercial
structures in the 500-year floodplain. The estimated damages resulting from the 100-year flood is
$5,779,700 (1990 dollars). The estimate of the number of structures and cost of damages in the
floodplain are based on aerial photography and a 1994 "Flood Control Report for Boxelder
Creek, Spring Creek, Dry Creek at Fort Collins, Colorado".
Because of the network of irrigation canals which intercept small to moderate flood flows and
much of the excess drainage from entering the lower Dry Creek basin in Fort Collins, a false
perception of the flood hazard has prevailed resulting in development of lower Dry Creek basin
in the City. These canals, however, do not have the capacity to intercept larger flood flows, such
as the 100-year event, and increased drainage flows from new development in the lower basin of
Dry Creek is already increasing the magnitude and frequency of those flows.
Fossil Creek Floodplain
Fossil Creek has no structures in the floodplain. Fossil Creek is a generally incised channel with
limited overbank flooding except in areas behind roadways or other obstructions which cause
backwater conditions. As discussed above in the channel stability section, the primary hazard to
structures near the floodplain is channel instability including lateral and/or vertical erosion and
deposition, channel meander migration,bank undercutting, and meander cutoffs. For this reason,
"erosion buffer limits" were established to protect man-made structures from the instability of the
river system. The erosion buffer limits establish minimum setback for development near Fossil
Creek,thereby eliminating all development within the flood and erosion hazard area.
Boxelder Creek and Cooper Slough Floodplains
The portion of the Boxelder Creek floodplain which is within the City limits is just south of
Colorado State Highway 14 where the Boxelder Creek flows beneath I-25 and continues flowing
southwest to its confluence with the Poudre River. Between the creek crossing at I-25 and
Prospect Road there is one (1) residential structure near the floodplain. Below Prospect Road, the
Boxelder, Cooper Slough and Poudre River floodplains are continuous. Structures outside the
City limits on the east side of Interstate 25 are also subject to the flood hazard.
27
The majority of structures located in the Cooper Slough floodplain are along Colorado State
Highway 14 (Mulberry Road)just east of Interstate 25 outside of the City limits in Larimer
County. The structures along Highway 14 are primarily commercial and subject to shallow
flooding as a result of overflows from the Boxelder and Cooper Slough Floodplains.
The only portion of the Cooper Slough floodplain within the City limits is currently (1995)
immediately north and south of Vine Drive. To the north of Vine Drive up to the Larimer and
Weld Canal,which marks is the upper drainage basin limits there are approved plans for a
residential subdivision in this area,however, is not mapped in the SFHA. South of Vine Drive to
Highway 14 there are approximately 7 structures within the 100-year floodplain in Larimer
County. There is 1 pre-Firm structure within the City limits adjacent to the Cooper Slough on
West Vine Drive. South of Highway 14 to confluence with Boxelder Creek, outside the City
limits, there are over 40 structures in the 100-year floodplain.
The number of structures in the Cooper Slough and Boxelder Creek floodplains is based on 1988
aerial photography for the "Cooper Slough within Latimer County, CO.", Limited Map
Maintenance Program Study (LMMP),November 1993, prepared by Love and Associates. The
floodplain delineation did not,however, extend above Vine Drive to the Larimer and Weld Canal
which receives overflows from the Boxelder Floodplain. In addition, it is not known how many
additional structures have been built within the 100-year floodplain in Larimer County
jurisdiction east of 1-25.
Urban Floodplains and Stormwater Basins
In addition to the above mentioned floodplains, the Stormwater Department has subdivided the
City into Stormwater Basins (Figure 4). Each Stormwater basin has an associated Master Plan
which includes hydrology calculations and flood hazard delineations associated with the 100-
year rainfall. Flooded areas within the stormwater basins, other than those previously mentioned,
are associated with urban runoff rather than a river or stream However, several basins (Spring
Creek, Dry Creek, etc...) do share the names of the streams that are the receiving waters for their
respective basins. Urban floodplains are administered the same as riverine floodplains with
regard to permitting and design requirements. Please refer to the Urban Flash Flooding section
above for identifying historically problematic areas. In addition,the Old Town Master Plan
identifies specific areas within Old Town with particular flood problems such as the intersections
of LaPorte and Shields, Mason and Mulberry, Locust and Whitcomb, Locust and Whedbee, Plum
and Bluebell, and Magnolia and Washington Streets.
Critical Facilities
Critical facilities are buildings or sites that deserve special attention because they are vital to the
community or pose a special hazard during a flood. Examples of critical facilities include
structures or facilities that produce, use, or store highly volatile, flammable, explosive, toxic
and/or water reactive materials; Hospitals,nursing homes, and housing likely to contain
28
occupants who may not be sufficiently mobile to avoid death or injury during a flood; Police
stations, fire stations, vehicle and equipment storage facilities, and emergency operations centers
that are needed for flood response activities before, during, and after a flood; and, Public and
private utility facilities that are vital to maintaining or restoring normal services to flooded areas
before, during, or after a flood.
Critical facilities within the City of Fort Collins are as follows.
a. Hospitals; Poudre Valley Hospital (PVH) at 1024 Lemay Avenue, is the only
hospital in Fort Collins and is not located in a floodplain.
b. Water Treatment Plant; The City Water treatment Plant is located at 4316
LaPorte Avenue and is not located in a floodplain. It is however, located
immediately below Horsetooth Reservoir, and therefore like most of Fort Collins,
susceptible to dam failure. Water Treatment Plant#2 is located in Poudre Canyon
outside the City limits and may be susceptible to flash flooding in the canyon.
C. Waste Water Treatment Plants (WWTP); WWTP #1 is located at 900 Riverside
Avenue at Mulberry Street (State Highway 14) and is located within the Poudre
River I00-yea;and/or 500nyear floodplain: WWTP #2 is-located at 3036 East
Drake Road near the Northern Colorado Nature Center and is located adjacent to
the 100-year floodplain. A levee has been constructed which removes WWTP 42
from the Poudre 100-year floodplain.
d. Hazardous Materials Facilities; The Larimer County Office of Emergency
Management(1994) records for Superfund Amendments and Reauthorization Act
(SARA)Tier II Reports for the City of Fort Collin was reviewed. The following
facilities were identified from the most recent list containing approximately 50
reporting facilities. The following produce and/or store hazardous materials and
are located within a floodplain. In addition, a list of all City owned facilities was
reviewed. None of the following facilities are considered critical.
Coastal Mart 805 Lincoln Ave. (Poudre River)
Mini Mart 1801 N. College-Ave: (Dry Creek)
Pameco Corp. 1234 N. College Ave. (Dry Creek)
Thermal Co. 1324 N. College Ave. (Dry Creek)
V ipont 1625 Sharp Point Dr. (Poudre River)
Western Mobile Larimer County outside City limits 1800 N. Taft
Hill Rd. and 3000 S. CO. RD 9. (Poudre River)
e. Poudre Fire Authority; Fire Stations#1 through#5 are located within the City
limits as follows.No fire stations are within any floodplain.
Station#1; 505 Peterson St.
Station#2; 4015 South Bryan St.
29
Station 93; 2000 Mathews St.
Station#4; 2030 Devonshire Dr.
Station#5; 4615 Hogan Dr.
Station 46; 2511 Donnella Ct. (Larimer County)
f. Police Services and City Hall; The City only has one station located at 300
LaPorte Avenue-and-is-not in-a-toodplain_-City HalLis-located-at the-same-
location
g. Emergency Operations Center(EOC); is currently located at 200 West Oak Street
in the basement of the Courthouse and is not in a floodplain. The City will
relocate the EOC to North Shields Street on the north side of the Poudre River just
outside of the floodplain and outside the City limits. The relocation of the EOC to
the north side of the Poudre River may present access problems in the event of a
large magnitude flood on the Poudre River which eliminates cross river
accessibility.
The local chapter of the American Red Cross is located at 120 Saturn Drive and is
not located in a floodplain. The Red Cross would be involved in aspects of
emergency response such as setting up temporary facilities for flood victims.
h. Equipment Storage; Flood response equipment and vehicles are stored at the
Equipment Services facility at 835 Wood Street outside of the floodplain and at
the Streets facility located on Vine Drive. Access to the streets facility could be
difficult since it is surrounded by the Dry Creek and Poudre floodplain. The
facility itself is located outside the floodplain since Vine Drive acts as a berm to
the north and blocks floodflow.
i. Special Care Facilities; A review of the phone book for special care facilities,
nursing homes, was conducted to determine if any are within any floodplains. One
special care facility (Shamrock Manor) is located within the Spring Creek
floodplain just upstream of Taft Hill Road. The City is programmed to acquire
and relocate this structure in 1996.
j. Utility facilities; Light and Power has 5 existing substations in Fort Collins
including the Richard Lake, Linden Tech., Overland, Drake, and Harmony
substations. Only the Linden Tech substation is located in a floodplain(Poudre
River). Even if that substation is inundated during a large flood,Light and Power
indicatettth- serviz-mmay-nutnecessarily be-strut-down ai nd-may be bypassed
through other sub-stations. The Platte River Power Authority has 9 substations
located within Fort Collins. Only the Timberline Substation, located at 1809
Timberline Road, is located within a floodplain(Spring Creek).
30
IV. DEVELOPMENT TRENDS
In February, 1976, a report by the United States Bureau of the Census indicated that the City of
Fort Collins had the fourth highest growth rate among Standard Metropolitan Statistical Areas
(SMSA) nationally (a SMSA is a county which contains a city with a population of over 50,000).
The census report revealed that the city's population increased from 43,337 on April 1, 1970,to
55,470 on July 1, 1974, an increase of 28 percent. A subsequent report from the Bureau of the
Census issued in February, 1979, indicated the Fort Collins population as of July 1, 1977, was
58,107, or an increase of 4.8 percent over the 1974 figure.
In 1994 the City Building Inspection Department issued 1,462 building permits for new
residential units. The 1, 462 total was the largest new unit total since 1985,when the City issued
permits for 1,493 new units. The 1994 figure is the 6th largest total since 1970. The City will
have a total of approximately 40,480 residential units in 1995.
Local estimates have indicated population totals and growth rates of approximately 3.8%
annually. The current (1995) population estimate for the City of Fort Collins is 99,726.
The rapid growth which the City of Fort Collins is currently experiencing and the effects which
this growth has on the community demonstrates the need for farsighted and effective
comprehensive planning. Please refer to "Trends, A Review of Economic and Social Conditions
in Fbrt Collins", Planning Department, June 1995 for detailed city analyses. Floodplains in the
City are experiencing development pressures because of the available vacant lands. Development
trends within the floodplains are as follows;
Cache La Poudre River
The Cache La Poudre River corridor has development occurring primarily along North College
Avenue and east near I-25. The City has adopted the "North College Avenue Corridor Plan"
(1995). The mission of the Plan is to remove barriers and make incentives for development and
redevelopment and to integrate the Poudre River into the plan as Open Space and Natural Areas.
The Plan's policy statement LU-8, states that "the Cache La Poudre River and surrounding area
(floodplain) should be integrated into the Corridor with compatible land uses which complement
and enhance the river's special qualities. Urban land uses as outlined in the Downtown Plan
should be encouraged to locate on the north side of the river as well as the south." Policy
statement OF-5 states that "riparian areas, stands of large trees, and high quality open space
should be conserved as amenities and connections, and be incorporated into the design of new
development." In the area of the North College Avenue Corridor Plan, the Dry Creek and Poudre
floodplains are continuous, and therefore, development trends may affect both floodplains.
Dry Creek
Dry Creek has experienced heavy development in the distant past, particularly along the North
31
College Avenue corridor-. Much ofthe Dory Creek floodplain alongNorth-College Avenueshas
already been developed, however, future development and redevelopment is likely as outlined in
the North College Avenue Corridor Plan. In addition, the residential area east of the North
College Avenue business district has also been heavily developed in the past. Most of the
floodplain land was already developed prior to the City participating in the NFIP.
The North College Avenue Corridor Plan identified several new zoning districts including the
"Highway Commercial Zone" which encompasses properties on North College Avenue from
Vine Drive north to Eaton Ditch, with an extension along the south side of Hickory Street. This
zone is all within the Dry Creek floodplain. The highway commercial zone provides for the
existing types of auto-oriented highway businesses to continue to operate and define the
character of North College Avenue,however,the plan also encourages new development and
redevelopment of this zone. A wide range of land uses is allowed, including commercial,retail,
services and light industry.
Future storm drainage improvements along Dry Creek are being assessed with the purpose of
confining flood flows and reducing the associated floodplain. The improvements include a
diversion channel that intercepts flood flows and diverts them west of the North College area and
into the Poudre River. The overriding issue, however, is the funding for these improvements. The
removal of the Dry Creek floodplain is considered the single greatest incentive for future
development.
Spring Creek
Although much of the Spring Creek basin is already developed, there is residential "in-fill" and
subdivision development occurring within the basin. Since the channelization and improvement
projects were completed in the late 1980's and early 1990's,there is only limited pressure on
floodplain lands. The channelization and floodplain improvements eliminate much of the
overbank flooding and maintains floodflow conveyance within the main channel for most of the
stream, thereby reducing the total area of floodplain land. In fact, approximately 79 structures
have been removed from the regulatory floodplain as a result of the channel improvement
projects. It is anticipated that lands which were formerly designated as 100-year floodplain along
the Spring Creek channel will be developed in the future. The revised FIS removes a substantial
amount of land from the floodplain delineation and may encourage development adjacent to the
creek on lands which were formerly designated floodplain.
Fossil Creek
Fossil Creek basin is experiencing relatively heavy development pressure. There is vacant farm
land which is primarily being platted for residential subdivisions. Since the Fossil Creek
floodplain is narrow, as a result of the incised nature of the channel, the primary concern is
channel instability. As a result, channel stability studies are required as part of subdivision
proposals to ensure that encroachment into the floodplain or erosion buffer limits does not occur.
32
Boxelder Creek and Cooper Slough
Boxelder Creek and Cooper Slough are primarily located within the Larimer County jurisdiction
with-limited-development-within-the-City limits._The headwater area of the Cooper Slough
between East Vine Drive and the Latimer and Weld Canal currently has an approved subdivision
development plan which includes proposed realignment and alteration of the channel and
floodplain. The actual flooding in the area of the proposed subdivision is the result of Boxelder
Creek overflows across I-25 and into the Cooper Slough.
V. DEVELOPMENT CONTROLS
There are several major controls of development in the City including:
a. City Council: The City Council is responsible with regard to the operative details
for the enactment of ordinances and resolutions of the City. The City Council also
is responsible for appointing members to various City Boards such as the
Planning and Zoning and Storm Drainage Boards.
b. Planning and Zoning Board: The functions of the Planning and Zoning Board are
to advise City Council on zoning, subdivision, annexations, major public and
private projects and long range planning; to exercise the authority vested in it by
state planning and zoning laws; to cooperate with school, county, and any other
planning and zoning board to enter into agreements to promote uniform planning
and zoning within and without the city; to take final action to approve, disapprove
or approve with conditions all planning items in accordance with City Code and
Charter.
C. Storm Drainage Board: The functions of the Storm Drainage Board are to make
recommendations to City Council concerning the schedule, costs, funding, and
benefits of stormwater facilities in the City. The board reviews and makes
recommendations to the City Council on Master Drainage Plans to be developed
for stormwater facilities. The board also makes recommendations regarding
policy or technical matters related to stormwater management and has authority
witirregar&to-appeals--and variances to floodplain regulations:
d. Land Development Guidance System(LDGS): The LDGS is a legal mechanism
based on City codes and State statutes under which land development or
redevelopment occurs. The LDGS is a tool that the City uses to implement its
long range land use policies and allow more flexible zoning through the P.U.D.
process.
e. Floodplain Regulations: The City has adopted floodplain regulations which
establish performance standards and criteria,restrictions to development, and the
33
regulation of development and modification activities in all floodplains within the
City.
f. Master Drainageway Plans: Master Drainageway Plans are used by the City as
guidance for existing and future development within individual stormwater basins
and for floodplain management. The Master Drainageway Plans also provide the
basis to charge fees to fund major drainage improvements.
g. Ownership: The City owns a number of Parks and Open Space land along the
Cache La Poudre, Spring Creek, and Fossil Creek. The Stormwater Department
owns and maintains several regional detention ponds and drainageways which are
in the floodplain.
h. Storm Drainage Design Criteria and Construction Standards: The purpose of the
criteria and standards are to set forth the technical criteria to be used in the
analysis and design of drainage systems within the City of Fort Collins and its
Urban Growth-Area. All subdivision plats,planned-unit-developments, or any-
other proposed construction must include an adequate plan for storm drainage and
erosion control. In addition,the manual sets forth minimum standards for
construction and installation of storm drainage facilities.
i. City of Fort Collins Comprehensive Plan: The Comprehensive Plan is not one
document, but is composed of Elements, such as the Landuse Policy Plan, Goals
and Objectives, Open Space Plan, and Natural Areas Plan. The elements of the
Comprehensive Plan establish policies and goals for various development
activities in the City of Fort Collins.
VI. FLOODPLAIN AREAS THAT PROVIDE NATURAL AND BENEFICIAL
FUNCTIONS
Surface waters, floodplains, and watersheds must be viewed as parts of one ecological system.
This system exists in a state of dynamic equilibrium. If a disturbance occurs in one part of the
system, the entire system will readjust toward a new equilibrium. The geomorphological,
hydrological, and biological effects of the system's readjustments may be evident far upstream
and downstream from the disturbance and may last for a long period of time. Therefore,
floodplain development and modification should be viewed with caution and with careful
assessment of the potential adverse impacts on the natural and beneficial functions.
Floodplains in their natural or relatively undisturbed state provide three broad sets of natural and
beneficial resource values: (1) water resources values including natural moderation and
attenuation of floods;water-quality maintenance; and groundwater recharge; (2)biological
resource values including large and diverse populations of plants and animals; and, (3) societal
resource values including historical, archeological, scientific, recreational, and aesthetic sites.
34
Table 1 lists a number of natural and beneficial functions provided by floodplains.
Where location in the floodplain is the only practicable alternative,the potential for adverse
impacts and the existing floodplain values should be identified. The design or modification of
the action to avoid or minimize potential harm to or within the floodplain should be pursued. A
floodplain management goal is to minimize the adverse environmental impacts on natural
floodplain values, as well as to minimize potential risk to the proposed action itself and to lives
and property.
The City of Fort Collins,Natural Resources Division,Natural Areas Policy Plan identified
natural areas within the Urban Growth Area using a number of criteria including; 1) contain a
high quality wildlife habitat; 2) currently serve, or potentially serve (if enhanced), as a wildlife
corridor between higher quality wildlife habitats; 3) contain significant geological or
archeological sites; 4) contain rare native plant species or communities, and; 5) support rare or
important animal species and communities. Figure 5 shows the river and creek resource areas
identified by the City Natural Resources Department.
Eight natural resource areas were defined based on the above criteria and additional mapping
which included the Poudre River, Fossil Creek and tributaries, Spring Creek, Cooper Slough,
Boxelder Creek, and Dry Creek. Acreage of major habitat types present within the resources
areas was mapped. In addition, rare plant sites, key areas for endangered, threatened, and rare
animals, key areas for raptors, migrant songbirds, and nesting great blue herons, key areas for
water fowl and aquatic insects, and river resources areas were determined. In addition, the plan
describes the natural features, existing public facilities, and challenges and opportunities for the
river resources areas. Refer to the Natural-Areas Policy Plan for details.
VII. FLOODPLAIN MANAGEMENT
Review of Possible Floodplain Management Activities
It is important that the City consider all possible ways to reduce flood losses and protect natural
resources. To ans=that the full range of alternatives were reviewed,the list of strategies and
tools recommended by the Unified National Program for Floodplain Management(FEMA
Publication 248, 1994)was used.
The Unified National Program lists four strategies and numerous tools to prevent or reduce flood
losses and to preserve and restore the natural and beneficial functions of floodplains. The
strategies and tools are presented in Table 2.
35
Natural and Beneficial Floodplain Functions
Floodplains that are relatively undisturbed (or have been restored to a nearly natural state)
provide a wide range of benefits to both human and natural systems. These benefits take
many forms: some are static conditions (like providing aesthetic pleasure) and some are
active processes (like filtering nutrients). There is some ambiguity over which of these
benefits are properly termed 'functions,' which are 'resources,' and where the terms overlap.
A fairly well accepted (but not necessarily comprehensive) list follows.
Water Resources: resources and functions that are part of or provide a benefit to the
hydrologic cycles on the earth's surface and below ground
Natural Flood and Erosion Control Water Quality Maintenance
• Provide flood storage and conveyance • Filter nutrients and impurities from runoff
• Reduce flood velocities • Process organic wastes
• Reduce flood peaks • Moderate temperature fluctuations
• Reduce sedimentation
Groundwater Recharge
• Promote infiltration and aquifer recharge
• Reduce frequency and duration of low surface flows
Biologic Resources: resources and functions that benefit plants and animals
Biological Productivity Fish and Wildlife Habitats
• Support high rate of plant growth • Provide breeding and feeding grounds
• Maintain biodiversity • Create and enhance waterfowl habitat
• Maintain integrity of ecosystem • Protect habitats for rare/endangered species
Societal Resources: resources and functions that directly benefit human society
Harvest of wild and cultivated products Recreational Opportunities
• Enhance agricultural lands • Provide areas for active and passive uses
• Provide sites for aquaculture • Provide open space
• Restore and enhance forest lands • Provide aesthetic pleasure
Areas for Sciendfic Study and Outdoor Education
• Contain cultural resources (historic and archaeological sites)
• Provide opportunities for environmental and other studies
Excerpted from Appendix A of A Unified National Program for Floodplaln Management,
1994, Federal Interagency Roodplain Management Task Force, FEMA - 248.
Table 1. Natural and Beneficial Floodplain Functions
i
1 .
1 �
1 1
i coon wv.u
1,hL
1j 3
1
2
1 MOmI Tzlzz�
COO
1. 2'
h
1iY1GaM1/iA WIIWI
+
1 Figure5. River and creek resource areas: (1) Poudre River; (2)
Fossil Creek; (3) Spring Creek; (4) Cooper Slough; (5) Boxelder
1 Creek; (6) Dry Creek.
1
Strategies and Tools from the Unified National Program for Floodplain Management
Strategy 1: Modify htunan susceptlbiliry to flood damage and disruption by avoiding hazardous, uneconomic, or
unwise use of floodplainc. Tools include:
► Floodplain regulations, e.g.,zoning to steer development away from hazardous areas or natural areas
deserving preservation; subdivision regulations; and building,health and sanitary codes
► Development and redevelopment policies on the design and location of public services,utilities, and critical
facilities land acquisition; open space preservation, and permanent relocation of buildings
► Floodproofmg of new buildings and retrofitting of existing ones
► Flood forerasting, warning systems, and emergency plans that prepare people and property for flooding
► Preservation and rmtaation of the natural resources and functions of floodplains
Strategy 2-- Mod;wfyy At impact offloodng-by assisting individuals and communities to prepare for,respond to,
and recover from}foods. Toolsiaclude:
► Information and education to assist self-help and protection measures
► Flood emergency measures to protect people and property during the flood
► Disaster assistance, flood insurance, and tax adjustments to reduce the financial impact of flooding .
► Post flood recovery
plans and programs to help people rebuild and implement mitigation measures to protect
against fume floods
Strategy 3: Modify flooding through projects that control flood waters. Tools include:
► Dams and reservoirs that store excess waters upstream of development
► Dikes, levees,and floodwalls that keep wares away from developed areas
► Channel alterations that make the chamml more efficient, so waters will overbank flooding will be less
frequent
► High flow diversions that send excess waters off to undeveloped areas
► Land treatment to hold as much rain as possible where it falls so it can infiltrate instead of mmming off
► On-site detention measures to store excess runoff and flood flows
► Shoreline protection measures that protect island development and account for the natural movement of
shorela d features
Strategy 4: Preserve and restore the natural resources and functions of floodphtins by maintaining and
reestablishing floodplain environments in their natural state. Tools include:
► Flo�odpplain, wetlands,and coastal barrier resources regulations, e.g..zoning, to steer development away from
hazardous areas or natural areas deserving preservation; subdivision regulations; and building, health and
sanitary codes
► Development and redevelopment policies on the design and location of public services, utilities, and critical
facilities; land acquisition; open space preservation; permanent relocation of buildings;restoration of
floodpltins and wetlands; and preservation of natural functions and habitats
► Information and education to make people aware of natural floodplain resources and functions and how to
protect them
► Tax adjustments to provide a financial encouragement for leaving lands in their natural sate
► Beach nourishment and dune building to prmct inland development by maintaining the natural flood
protection features
Table 2. Strategies and Tools from the Unified National Program for Floodplain
Management
Coordination with Other Agencies
In order to check if other agencies are involved in activities that may affect or support the City's
Floodplain Management Program the following agencies were contacted;
a. Colorado Water Conservation Board(CWCB); One project that the CWCB is
preparing-that may affect-floodplain-management-in-Fort-Collins-is the_
preparation of a "Colorado Flood Hydrology Manual". The City is a member of
the Advisory Committee for the manual.
b. Federal Emergency Management Agency Region VIII; FEMA Region VIII is
involved in initiating discussions on alluvial channel hydraulics as it affects flood
insurance studies and floodplain delineation. The City attends meetings on this
topic with FEMA.
C. -Larimer County; The County has completed a revised FIS of the Poudre River
downstream of Fort Collins. The City ensured that the recent City revised FIS and
the adjacent County revised FIS are tied together and Larimer County participated
in the Cooper Slough and Poudre River Flood Insurance Study updates.
d: Colorado Office of Emergency Management-and-local-chapter of the American
Red Cross; The City Emergency Manager coordinates emergency management
operations with these agencies.
e. City of Fort Collins; Police Services,Natural Resources Division, Parks and
Recreation, Water and Waste Water, Light and Power, Transportation
Department, and the Planning Department were contacted and given the
opportunity to review this document in order to coordinate efforts, increase
interdepartmental communication, and promote cooperation with regard to overall
city goals as they pertain to floodplain management.
Floodplain Management Activities and the Community Rating System
The following activities are currently being implemented as part of the comprehensive floodplain
management plan for the City of Fort Collins. The rivers and streams in the City of Fort Collins
will continue to flood periodically, therefore, the goal of floodplain management activities is to
minimize the effects of flooding to life and property in floodprone areas through increased public
awareness of the flood hazard, flood mitigation and protection, and maintaining, enhancing, and
improving the natural and beneficial functions of floodplains.
The City of Fort Collins entered the Community Rating System(CRS) in 1990 as part of the City
floodplain management program. The CRS Program provides an incentive for communities to
do more than just regulate construction of new buildings to minimum National Flood Insurance
39
Program standards. Under CRS, flood insurance premiums are adjusted to reflect community
activities that reduce flood damage to existing buildings,manage development in areas not
mapped by NFIP.protect new buildings beyond the minimum NFIP protection level, help
insurance agents obtain flood data, credit flood mitigation, promote multi-objective floodplain
management, and help people obtain flood insurance.
The objective of CRS is to reward communities that are doing more than meeting the minimum
NFIP requirements to help their citizens prevent or reduce flood losses. The CRS provides an
incentive for communities to initiate new flood protection activities. The goals of CRS are to
encourage,by the use of flood insurance premium adjustments, community and state activities
beyond those required by the NFIP to reduce flood losses, facilitate accurate insurance rating,
and promote the awareness of flood insurance.
The Riegle Community Development and Regulatory Improvement Act of 1994, Subtitle C-
Ratings and Incentives for Community F000dplain Management Programs, Section 541 mandates
FEMA to establish its CRS, a system that the FIA has had in place for years. The goals for the
statutorily mandated CRS are as follows;
a. to provide incentives for measures that reduce the risk of flood or erosion damage
that exceed the measures set forth the National Flood Insurance Act of 1968 and
evaluate such measures;
b. to encourage adoption of more effective measures that protect natural and
beneficial floodplain functions;
C. to encourage floodplain and erosion management; and,
d. to promote the reduction of Federal flood insurance losses.
The CRS gives credits (reductions) on flood insurance premiums to local policy holders in return
for the community's adoption of more effective measures to reduce flood and erosion damages.
Special consideration is to be given to communities that recognize the natural and beneficial uses
of the floodplain. The amount of the premium credit is tied to the estimated reduction in flood
and erosion damage resulting from the measures that exceed the minimum NFIP standards.
Fort Collins will continue to participate in the CRS Program. The activity number(i.e., Activity
310) listed below corresponds to floodplain management activities that the City of Fort Collins
receive credit for in the CRS program.
40
I. Activity 310: Floodplain Use Permits, Floodprooffng Certificates, and-Elevation
Certificates
a. The City of Fort Collins Code Section 10-37 requires that a Floodplain Use
Permit be obtained prior to construction or development within any floodplain.
Use permits are kept on file at the Stormwater Utility office.
b. The City of Fort Collins Code Section 10-36 requires and maintains (FEMA)
elevation certificates for lowest floor of all new construction and development
within any floodplain. The elevation certificates are available for public
inspection.
Elevation certificates have been maintained since Fort Collins entered the NFIP in
1979, however, FEMA elevation certificates have only been maintained since
entering the CRS Program in 1990. For buildings prior to this date and pre-
FIRM, elevation certificates are obtained whenever possible. Pre-1990 certificates
have been transferred to FEMA forms.
c The City of Fort Collins Code Section 10-36 requires and maintains (FEMA)
floodproofing certificates for all construction and development within any special
flood hazard area.
d. Floodplain Certification is maintained in electronic format(CRS program) and
submitted with the CRS application on disk.
Responsibility: Stormwater Department
Deadline: Ongoing
2. Activity 320: Map Information
a. The City of Fort Collins provides and will continue to provide map
determinations to all inquirers which includes; community number(080102),
FIRM panel number and suffix, effective FIRM index date, FIRM zone, base
flood elevation data, elevation datum used. In addition, for properties located in a
Special Flood Hazard Area(SFHA), the inquirer is informed of the flood
insurance purchase requirement and provided information upon request.
b. The map determination service is publicized at least once per year in one of the
following;
41
i. Board of Realtors mailing list
ii. Local newspaper article
iii. "City News" in utility bill
iv. Phone book "City Line" 493-2489,X808
V. Floodplain resident mailing outreach project
C. Documentation of all inquiries is maintained at the stormwater office.
Responsibility: Stormwater Department
Deadline: On going and annual mailings and advertisement of service
3. Activity 330: Outreach Projects
a. Floodplain outreach project-(OPF);-The-City o£Fort-Collinssends and will
continue to send, an annual mailing to residents in the SFHA of Dry Creek,
Spring Creek, and the Cache La Poudre River.
The mailing covers 10 topics as outlined in the CRS; the local flood hazard, a
base map of the hazard, flood warning system, flood safety, flood insurance,
property protection measures, floodplain development permit requirements,
substantial improvement requirements, drainage system maintenance, and the
natural and beneficial functions of floodplains.
b Community Outreach Project(OPC);
An article is published annually in "City News" which is sent to the entire
community with the utility bills. The article describes the Floodplain Management
Program and related services, the local hazard, flood insurance, drainage system
maintenance, permit requirements, and substantial improvements.
C. Additional annual outreach projects include (OPA);
i. Video broadcast of"Managing the Flow" and/or FEMA's "Best
Build" Video Series on Cable 27 (part of Flood Awareness Week).
ii. Annual article in"City News" on services provided by the
Stormwater Department(same as OPC).
iii. Annual article in local newspaper or local news letter on recent
events and services provided by the Stormwater Department.
iv. Phone book section on Emergency Preparedness.
V. "City Line" directory 493-2489.
X808 Floodplain Information.
42
X565 Flood and Flash Flood Safety.
vi. Flood Awareness Week -Annual Outreach booth(s) at City event
sponsored by Stormwater Department.
vii. Board of Realtors Mailing for CRS Activity 320 (required
publicity).
viii. Brochure display at the Stormwater Utility office covering all CRS
330 topics.
d. Floodplain mailing lists are maintained at the Stormwater office and submitted to
FEMA for use in their outreach projects.
d. Documentation of distribution and copies of the outreach projects are kept at the
Stormwater Department
Responsibility: Stormwater Department
Deadline: Annual mailings, articles,booths, and video broadcasts.
4. Activity 340: Hazard Disclosure
a. Federal law requires that the lending institution inform a buyer that the property is
the SFHA and requires purchase of flood insurance.
b. Some lenders/realtors provide hazard disclosure on the property disclosure forms,
however, there is no consistent distribution.
C. The Colorado Real Estate Commission has adopted forms which represent an
obligation on the part of the Agent or Broker to disclose any defects of which the
floodplain would qualify. In the State of Colorado there is also a Cause of Action
which mandates that the seller or representative of the seller disclose all
Actrimental conditions that exist on the property of which flooding is included.
Responsibility: Realtor/Lending Institution
Deadline: Ongoing
5. Activity 350: Flood Protection Library
a. The Fort Collins Public Library maintains at least one document on the FIRM and
Floodway Maps, flood insurance,protecting a building, flood hazard mitigation,
natural and beneficial functions of floodplains, and locally pertinent documents.
43
The same information is available at the Stormwater Department. A list of the
documents is maintained at the Stormwater Department Office.
b. Certification that the library maintains and will continue to maintain the flood
documents is kept at the Stormwater Department office.
C. This service provided by the library is advertised annually;
i. "City News" in the utility bill
ii. Local newspaper article
iii. Phone book "City Line" 493-2489, X808
iv. Annual floodplain resident mailing
Responsibility: Stormwater Department and Public Library
Deadline: Ongoing and annual publication
6. Activity 360: Flood Protection Assistance
a. The Stormwater Department provides and will continue to provide technical
advice to interested property owners on the flood hazard, on contractors, and on
flood protection measures. Information provided includes;
i. Site specific flood and flood related data, such as floor elevations,
data on historical flooding, or similar information so inquirers can
relate the flood threat to their properties.
ii. Providing types of contractors and consultants knowledgeable or
experienced in retrofitting techniques and construction. Because of
potential liability, the Stormwater Department cannot endorse any
particular contractor and may only provide general reference to
types of contractors to contact. Information on how to select a
contractor is also available.
iii. Make site visits to review flooding, drainage, and sewer problems
and provide one-on-one advice to the property owner. Also,
providing retrofitting advice and assistance.
iv. Providing advice and assistance on retrofitting techniques.
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b. This service is publicized annually.
i. "City News" inutility bill
ii. Local newspaper article
iii. Annual floodplain resident mailing
iv. City Line 493-2489,X808
C. Records of assistance provided are maintained at the Stormwater Department.
d. Technical qualifications of persons providing assistance are maintained at the
Stormwater Department.
Responsibility: Stormwater Department
Deadline: Ongoing and annual publication
7. Activity 410: Additional Flood Data
a. The City of Fort Collins maps and manages all floodplains, including those not
studied in detail by FIA and designated SFHA on a FIRM,to standards exceeding
those of the NFIP minimum requirements.
i. Regulatory flood elevation data has been developed for all floodplains
within the City of Fort Collins and is contained in the Master Drainageway
Plans. Flood elevation data is computed with the Army Corps of
Engineers HEC-2 model.
ii. Master Drainage Plan hydrology standards are based on fully developed
basin conditions and are therefore based on higher hydrology standards
that the FIS study standards. The Environmental Protection Agency
(EPA) Storm Water Management Model (SWMM) is used.
iii. The City Fort Collins Code has mandated a more restrictive floodway
standard of a maximum 0.5 foot rise, except Dry Creek which is a
maximum 1.0 foot rise. The floodway for Fossil Creek is not delineated
and is considered to be the same (equal) as the floodplain delineation
unless proven otherwise by accepted methods..
iv. The City of Fort Collins Stormwater Department revenues fund the Master
Drainageway Plan projects. All Master Plans are reviewed and accepted
by the State of Colorado Water Conservation Board.
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V. The Master Drainageway Plans include channel stability analyses when
necessary. The Fossil Creek basin plan requires channel stability studies
and delineation of erosion buffer zones and minimum setbacks.
Responsibility: Stormwater Department
Deadline: Ongoing with Master Plan updates approximately two per year
8. Activity 420: Open Space Preservation
a. Because one of the best ways to prevent flood damage is to keep floodprone areas
free from development, preservation of Open Space is an activity that the City
continually pursues. The acquisition of Open Space in the City's floodplains is
highlighted as part of the goals, policies, and objectives in the Elements of the
Comprehensive City Plan. Tables-3 and4 show-the areas-and acres designatedas
Open Space or Parks within the City's floodplains.
b. The property ispreservetlasOpen Space-which assures thattht-property will
remain open,that is, without buildings, fill or obstruction to flows, or loss of
floodplain storage. All portions of city and county parks, forest preserves, state
parks and state forests, and publicly owned natural areas that are within the
regulatory floodplain count toward open space credit. Buildings, such as
restrooms,historic buildings, and nature centers are counted as "necessary
appurtenance" for the open space use.
C. There are currently (1995) no open space areas of floodplain land with deed
restrictions;
d. There are community floodplain open space that are in an undeveloped natural
state, have been restored to a natural state, or protect the natural and beneficial
functions. The areas are preserved in the natural state by commitment of the
owner or development regulations.
e._ Tate Stormwater Tepartment_Master_Drainage-Planning prncessisusecLasone
vehicle to identify additional areas for Open Space acquisition.
Responsibility: Stormwater Department, Parks and Recreation, and Natural
Resources Division
Deadline: Ongoing
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Table 3. Open Space, Parks, and Natural Areas Located in Floodplains
SITE NAME ACRES OF OPEN SPACE COMMENTS
IN FLOODPLAINS
Archery Range (P) 30.4 Open Space
New Note Property (P) 263.56 Open Space
W.R.E.N. (P) 35 Open Space; Gravel Mine
Reclamation
Riverbend Ponds (P) 54.5 Open Space; Gravel Mine
Reclamation
Gustav Swanson(P) 11.43 Open Space
Udall Property (P) 12.33 Open Space
Lee Martinez Park(P) 57.76 Community Park
Strauss Cabin(P) 2 Historic Site
Springer Property (P) 23.73 Open Space
Williams Property (P) 1.4 Open Space
Buckingham Park(P) 5.75 Neighborhood Park
Heritage Park(P) 1.43 Neighborhood Park
*McMurray Area(P) 26.9 (County)Neighborhood Park
Legacy Park(P) 8.4 Neighborhood Park
UPRR Open Space (P) 3 Open Space
Prospect Ponds (P) 25.1 Open Space; Gravel Mine
Reclamation
Bignall (P) 0 Open Space
Milne (P) 44.27 Open Space
North Shields Pond(P) 10.01 Open Space
Salyer(P) 4.37 Open Space
Hickory Village (P) 37 Community Park
Flatirons (P) 121.86 Open Space; Gravel Mine
Reclamation
Environmental Learning 38.25 Colorado State University
Center(P) Natural Area
Alta Vista(D) 0.63 Mini Park
Ross Open Space (S) 18.22 Open Space
Rolland Moore Park(S) 16.74 Community Park
Spring Park(S) 4.71 Neighborhood Park
Spring Park Open Space (S) 2.05 Open Space
Edora Park(S) 5.45 Community Park
Creekside Park(S) 1.78 Mini Park
Youth Sports Park(S) 47.69 Undeveloped
Westfield Park(M) 2.07 Neighborhood Park
Troutman Park(M) 7.04 Neighborhood Park
Fossil Creek Park (M) 1.07 Community Park
Fossil Creek Park(F) 14.77 Community Park
Landing Park (MC) 0.54 Neighborhood Park
Southridge Golf Course 16.99 City Golf Course
(MC)
(P)Poudre River, (S)Spring Creek, (D)Dry Creek, (F)Fossil Creek, (M) Mail Creek,
(MC)McClellands Channel
Table 4. Area of Open Space Located in Floodplains.
TOTAL OPEN BASE
FLOODPLAfN ACRES SPACE MAP
ACRES
Cache La Poudre 1,278.82 818.45 1995 FIRM
Spring Creek 313 96.64 1995 FIRM
Dry Creek 539 0.63 1984 FIRM
Fossil Creek 200 14.77 1982 Master
Plan
Mail Creek 89 10.18 Master Plan
McClellands Channel 90.45 17.53 Master Plan
Burns Tributary* 18.67 0 1982 Master
Plan
Lang Gulch* 27.32 0 1982 Master
Plan
Smith Creek* 17.2 0 1982 Master
Plan
Cooper Slough 47.77 0 1995 FIRM
Boxelder Creek 202.31 0 1995 FIRM
GRAND TOTAL 2,823.54 958.2 ***********
*located in Fossil Creek Basin
9. Activity 430: Higher Regulatory_ Standards
The NFIP regulatory standards require that new residential buildings in the SFHA have
their lowest floor at or above the base flood elevation. Non-residential buildings may be
floodproofed to the baseflood elevation. Although the NFIP minimum standards provide
a great dealt of flood protection, damage can still result for-arary-reasoussu&as-error-
associated with estimates of flood heights, damage from events exceeding the 100-year
flood, urbanization and other changes in the watershed, reduction in storage capacity in
the flood fringe. For increased protection, the City of Fort Collins has adopted regulatory
standards that exceed the minimum requirements of the NFIP.
a. Freeboard; The City of Fort Collins Code requires that construction or
improvement of any residential structure shall have the lowest floor,
including the basement, elevated to or above the regulatory flood
elevation. The regulatory flood elevation is the elevation of not less than
one and one-half(1-1/2) foot above the baseflood elevation.
The City requires that construction or improvement of any commercial,
industrial, or other nonresidential structure shall either have the lowest
floor, including the basement, elevated to the level of the regulatory flood
protection elevation, or together with attendant utility and sanitary
facilities be floodproofed to the level of the regulatory flood protection
elevation.
b. Foundation Protection; The City of Fort Collins Code Section 5-26,
Buildings and Building Regulations, officially adopts the Uniform
Building Code and Standards for building construction standards.
C. Cumulative Substantial Improvements; The City of Fort Collins does not
have a cumulative substantial improvement regulation that requires that
improvements, modifications, additions, and reconstruction projects to
existing buildings be counted cumulatively for the life of the structure.
d. Lower Substantial Improvements Threshold; The City of Fort Collins has
adopted the substantial improvement threshold of 50%.
e. Protection of Critical Facilities; The City of Fort Collins does not have a
regulation in the City Code with regard to protection of critical facilities
from the 500-year flood.
f. Protection of Floodglain Storage Capacity; The City of Fort Collins does
not currently have a regulation for the protection of floodplain storage
capacity. The City does comply with the minimum NFIP standards that
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no development be allowed in the floodway that will increase the flood
elevation. The floodway regulation protects storage in the floodway but
does not address storage in the floodplain except in the Fossil Creek basin.
g. Natural and Beneficial Functions Regulation; The City does not currently
have regulation specifically addressing natural and beneficial functions as
described in the CRS. City Code, Sections 10-17 and 26-499, however, are
adopted regulations which protect natural and beneficial functions of
floodplains, specifically water quality maintenance and flood storage and
conveyance.
h. Enclosure Limits; The City of Fort Collins doe not currently have
regulations for enclosure limits which prohibit building enclosures below
the BFE.
i. Other Higher Standards; The City of Fort Collins has higher regulatory
standards that prevent flood losses or protect natural and beneficial
functions of floodplains.
City Code Section 26-543 officially adopts the Master Drainageway Plans
prepared with Stormwater Department funds. Master Drainageway Plans
include higher regulatory standards including "fully developed" hydrology
conditions and one half foot floodway calculations as discussed above. In
addition, however, the Fossil Creek Master Plan supplemental reports for
Mail Creek, Stanton Creek, Burns Creek, and Fossil Creek from Trilby to
Lemay Ave. delineate an "erosion buffer zone" to restrict development
along the floodplain.
j. Low Density Zoning; The City of Fort Collins does not have a low density
zoning ordinance limiting development in the floodplain as described in
the CRS.
k. Special Hazards Regulations; The City of Fort Collins does not have
adopted special hazard areas as described in the CRS. Development in the
Fossil Creek basin, however, is required to stay outside the erosion buffer
limits as determined in the detailed channel stability analysis described
above.
Responsibility: Stormwater Department
Deadline: Ongoing
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10. Activity 440: Flood Data Maintenance
a. The City of Fort Collins maintains an overlay map of the floodplains
within the City. The map is maintained at the Stormwater Department
office.
b. The City of Fort Collins Engineering Department maintains elevation
reference marks. The Black Bolt survey is used. Elevations are on listed
fire hydrant bonnet bolts and are given in feet above mean sea-level to the
nearest one hundredth foot based on USGS and/or USC&GS data.
C. All new development is tracked on the Development Tracking System
(DTS)which includes floodplain and floodway information. Holds are put
on Building permits and Certificates of Occupancy until Floodplain Use
Permits and Elevation Certificates are submitted and approved.
Responsibility: Stormwater Department and Engineering Department.
Deadline: Ongoing
11. Activity 450: Stormwater Management
a. Stormwater Management Regulations; The City of Fort Collins has officially
adopted "Storm Drainage Design Criteria and Construction Standards" which sets
forth the technical criteria to be used in the analysis, design, and construction of
storm drainage systems within the City of Fort Collins. In addition, City Code
Section 26, Article VIL, Stormwater Department are the officially adopted
regulations for stormwater management, as well as, specification for adoption of
Master Drainageway Plans for stormwater basins.
i. All proposed development is regulated.
ii. Detention storage requirements (Section 9, Design Criteria) for areas with
Master Drainageway Plans must be in accordance with the master plan for
that area. The release rate may vary from the 2-year historic to the 100-
year developed rate. In areas where master drainage plans are approved
but the improvements have not been constructed, detention may be
required until such time that an outfall is constructed.
Storage requirements in areas without master plans require detention
storage in accordance with the Standards and Criteria Manual. The
stormwater runoff shall not be released from developments at a rate greater
52
than the 2-year historic runoff. The amount of runoff to be detained on-
site shall be the difference between the 100-year runoff under developed
conditions and the 2-year historic runoff.
iii. Drainage and Erosion Control Reports (Section 2, Design Standards) are
required for all development proposals.
iv. The design storms and hydrology standards (Section 3, Design Standards)
used for calculation of stormwater runoff for development review are the
initial storm provisions (2 or 10 year storm) and the major storm
provisions (100-year storm). City Code section 26 requires pre- and post
development calculations so that post development runoff does not exceed
historic discharge.
V. City Code, Section 26-547 requires that the City shall maintain all
accepted public stormwater facilities located within city-owned land, city
rights of way and city easements and may maintain other accepted
facilities located within or adjacent to the city. Such public facilities
include those facilities which have been designed and constructed for use
by the general public. City Code, Section 20-44 also ensures that all other
facilities in the City will be maintained.
b. Stormwater Management Master Plans; The City of Fort Collins has adopted and
certified a regulatory program, Section 26-543,that regulates runoff according to
master stormwater drainageway plans.
C. State review of Stormwater Management Plans; The-Colorado Water
Conservation Board (CWCB) has reviewed and accepted the Master Drainageway
Plans for the City of Fort Collins. The CWCB will continue to review all Master
Plans for the City.
d. Freeboard; The City of Fort Collins Design Criteria Manual (page 4-5) specifies
freeboard requirement for new buildings in Zones B, C,D, and X as specified on
the FIRM. The maximum encroachment for structures near local and arterial
streets specifies that the depth of water over the street crown shall not exceed 6
inches. In addition, a drainage plan is required for all development in the City.
e. Erosion and Sediment Control Regulations; The City of Fort Collins requires that
an Erosion Control Report be prepared for all development. The Design Criteria
Manual, Section 8 Sediment Control Standards, describes adopted regulations on
sediment control standards. Erosion control measures must be implemented on
developing and redeveloping sites such that;preceding or during construction,
temporary erosion control measures shall be installed such that the maximum
53
amount of sediment discharge,by either wind or water erosion, shall not exceed
the historic sediment discharge due to the 10-year rainfall event, by more than 15
percent, and; after construction,permanent erosion control measures shall be
installed such that the maximum amount of sediment discharge, by either wind or
water erosion, shall not exceed the historic sediment discharge.
f. Water Quality Regulations; The City of Fort Collins has adopted a Water
Quality Code, Section 26-499,to protect the health, safety and welfare of the
citizens or the environment by imposing effluent limitations on discharge and
requiring best management practices. City Code Section 26-499 grants the right
to the Director to impose more stringent effluent limitations than required by the
Colorado Discharge Permit System(CDPS) and to add pollutant parameters to
those required by the CDPS. The Director may impose additional administrative
requirements for accelerated timetables for required sampling and higher
frequency sampling. The Director may also refuse any non-stormwater discharge
if, in the best professional judgement of the Director, such discharge would
significantly impair the health, safety or welfare of the citizens or the
environment.
Section 26-499 refers to the use of"best management practices" (BMP's) and the
Storm Drainage Design Criteria and Construction Standards Manual provides
details on BMP's..
The "Watershed Approach" was adopted in 1995 by City Council.
Responsibility: Stormwater Department
Deadline: Ongoing
12. Activity 520: Acquisition and Relocation
a. The City of Fort Collins has acquired and relocated buildings located in the
SFHA.
i. 32 structures were acquired by 1990 including; 29 manufactured homes, 1
commercial structure, and 2 residential structures during the Spring Creek
channelization project near Johnson Drive and College Avenue.
ii. 5 structures in the SFHA were acquired at the Stuart and Stover project
location.
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iii. 3 structures in the SFHA was acquired at the Cache La Poudre College
Avenue bridge project; 2 were located in the floodplain.
iv. The Building Department and Stormwater Department will "red-tag"
destroyed or substantially damaged buildings after a flood or other
disaster. These structures should not be reconstructed until the City meets
with the owners and explains alternatives to rebuilding onsite. Red tagging
will be completed within three days after a flood.
Responsibility: Stormwater Department
Deadline: Ongoing
13. Activity 540: Drainage System Maintenance
a. The City of Fort Collins Stormwater Department provides a drainage
system maintenance program that regularly inspects drainage systems and
removes debris. The drainage system includes the channels and basins
that carry or store surface water in developed areas, including those on
private property.
b. A copy of the "Operational Procedures" of the Stormwater Department
Facility Maintenance, Inspection and Debris Removal Program is
maintained at the Stormwater Department.
C. Stormwater drainage facilities debris removal inspections occurs at least
twice per year in the fall and spring. Copies of the Facility Maintenance,
Inspection, and Debris Removal Program inspection documentation forms
are maintained at the Stormwater Department.
d. Stream Dumping Regulations; The City of Fort Collins has adopted
regulations which prohibit the discharge of any pollutants into
watercourses (Section 26-499 and 20-44) and regulations which prohibit
the obstruction or pollution of ditches (Section 10-75).
e. This activity and stream dumping regulations are advertised annually by;
i. Annual floodplain resident mailing
ii. Annual local newspaper article
iii. City News article
Responsibility: Stormwater Department
55
Deadline: Ongoing and annual publication.
14. Activity 610: Flood Warning and Forecasting Program
a. The City of Fort Collins is provided some protection from floods through flood
warning and forecasting by the National Oceanic and Atmospheric
Administration,National Weather Service. These warnings are issued whenever
rainfall reports indicate that heavy rains capable of producing high runoff have
occurred or are occurring. Special forecasts of severe storms or rapid snowmelt
are made when warranted.
b. Flood threat recognition system; The Stormwater Department and City
Emergency Management Office have contracted with a local meteorologist
(Mountain States Weather)to forecast local severe storm patterns. A copy of the
contract is maintained at the Stormwater Department office.
C. The City monitors two (2) United States Geological Survey gaging stations on the
Poudre River for flood stage warning through the Colorado Division of Water
Resources, 303-831-7135, Division 1, Gaging Stations 18 (@Fort Collins), 19
(@Canyon Mouth).
d. The Poudre River gage at the mouth of the canyon is programmed with an
automated alarm that activates if the river stage reaches 6 feet (3450 cfs). When
the alarm is activated, a programmed call is made to the National Weather Service
in Denver, who, in turn, contacts the Larimer County Sheriffs Office Dispatch
and the City of Fort Collins. Once the Fort Collins dispatch is contacted,
warnings are disseminated using National Warning System(HAWS), Colorado
Crime Information Center Computer(CCIC), or direct call. Dissemination
systems are tested at least annually.
e. In the event of a flood, Police and Fire Services are equipped to broadcast flood
warning and safety information by mounted Public Address System on vehicles.
In addition, the Civil Emergency Alert System; which overrides local cable'fAT
channels for an audio message is activated. The entire City is covered by the
Emergency Broadcast System as well.
f. The City of Fort Collins Police Services has published an Emergency Operations
Plan for the city which includes a basic response flood plan(Annex K).
Responsibility: Stormwater Department and Police Services
Deadline: Ongoing
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14. Activity 630: Dam Safety
a. The are 45 high hazard dams and 42 moderate hazard dams in Larimer County.
Horsetooth Reservoir just west of Fort Collins poses the most immediate threat.
The State of Colorado has a dam safety program that has been accepted by the
Federal Emergency Management Agency for CRS credit.
b. Annex K of the City Emergency Operations Plan includes a basic operations plan
in the event of a flood (dam failure).
C. The Dam Evaluation for Emergency Notification Direction(DEFEND) Manual
was prepared by the City of Fort Collins to provide essential information to City
Emergency Services and Stormwater Department personnel in order to determine
a dam failure impact on the City of Fort Collins and to be able to respond
immediately.
d. The U.S. Bureau of Reclamation has prepared a Emergency Preparedness Plan
Brief for the Horsetooth Dams and Reservoir.
e. The State of Colorado has an approved Dam Safety Program
Responsibility: State of Colorado, State Engineer
Deadline: Ongoing
VIII. EVALUATION AND REPORT
Floodplain management measures require periodic evaluation to determine whether:
i Objectives are being met
ii. Original program objectives are still valid
Objectives established for a floodplain management plan may change over time for any of
several reasons. For example, changes in landuse regulations, community growth, or
construction of a dam or diversion channel may affect regulation of the flood hazard. A thorough
analysis of the program is appropriate if any major changes have occurred in the objectives:
Program objectives should be evaluated at a minimum every five(5) years, as well as, when any
significant event occurs which affects the extent or nature of problems and/or needs.
57
An annual review of the program will be made to determine whether individual measures are
meeting their objectives. Annual review provides the basis for strengthening operations,
modifying measures, or adding new measures to the program to enhance overall performance.
For measures requiring some local financial input, the budget will also be reviewed.
Annual review updates consisting of administrative changes and/or program activity
modifications will be made to the document text when required. All administrative and program
activity text updates made will consist of revisions that do not require approval by the City
Council. For example;the-addition of a Geographic Information System (CI r' for floodplain
mapping or the addition of an outreach project would be considered administrative changes.
Revisions to City Code and/or Floodplain Policy will only be made to the plan text after adoption
by City Council.
As part-of the annual review, the required annual CRS progress report will be completed. The
Stormwater Department will prepare an annual report on progress toward completing the plan.
The document will be distributed to the local media and the City Council and be made available
to the public. The progress report will be submitted to the state and FEMA as part of the annual
recertification. The report will include;
i. A review of the original plan
ii. A review of any floods that occurred during the year
iii. A review of each element or objective of the original plan, including how much
was accomplished during the previous year
iv. A discussion of why any objectives were not reached or why implementation is
behind schedule
V. Recommendations for new projects or revised objectives.
58
PART B
CITY OF FORT COLLINS
FLOODPLAIN POLICY AND ADMINISTRATION
OF FLOODPLAIN REGULATIONS
59
I. DEFINITIONS
(please refer to the National Flood Insurance Program,44 CFR 59.1 for additional definitions)
Areas of Special Flood Hazard shall mean the land in the floodplain subject to a one percent or
greater chance of being equalled or exceeded in any given year. Areas of the floodplain
designated as Zones A, AE, AO, AH, Al-30 on the FIRM for the City of Fort Collins and other
areas designated as floodplain by the City of Fort Collins are included.
Addition shall mean any alteration to an existing structure which results in any increase in the
structure's floor area.
Appeal shall mean a request for a review of an interpretation of any provision of City Code
Article II, Section 10, made by the Director of the Utility Services or designated representative.
Basement shall mean any area of a building having its floor subgrade (below ground level) on all
sides.
Base Flood shall mean the flood having a one-percent chance of being equaled or exceeded in
any given year, also known as the "100-year" flood. The base flood is a statistical concept used
to ensure that all properties subject to the National Flood Insurance Program are protected to the
same degree against flooding.
Base Flood Elevation shall mean the elevation for which there is a one-percent chance in any
given year that flood levels will equal or exceed it.
Change in a Watercourse shall mean any change in an existing thalweg, bed, or bank of a
watercourse.
Conveyance Zone shall mean those portions of the floodplain required for the passage or
conveyance of the one hundred year flood based on equal encroachment(or other method if
approved by the City of Fort Collins) of the floodplain from the edges of the flood channel to a
point where the one hundred year flood profile will be raised by six inches or more, after
considering a reasonable expectation of blockage at bridges and other obstructions by flood
borne debris.
Construction see "development" and "start of construction".
Critical Facilities shall mean structures or facilities that produce, use, or store highly volatile,
flammable, explosive,toxic, and/or water-reactive materials; Hospitals, nursing homes, and
housing likely to contain occupants who may not be sufficiently mobile to avoid death or injury
during a flood; Police stations, fire stations, vehicle and equipment storage facilities, and
emergency operations centers that are needed for flood response activities before, during, and
60
after a flood; and, Public and private utility facilities that are vital to maintaining or restoring
normal services to flooded areas before, during, and after a flood.
CRS refers to the Community Rating System.
Development shall mean any man-made change to improved or unimproved real estate,
including but not limited to buildings or other structures,mining, dredging, filling, grading,
paving, excavation or drilling operations or storage of equipment or materials located within the
area of special flood hazard.
Drainway or Drainageway shall mean a natural or artificial land surface depression with or
without perceptibly defined beds and banks to which surface runoff gravitates and collectively
forms a flow of water continuously or intermittently in a definite direction.
FEMA refers ,to the Federal Emergency Management Agency.
Fill shall mean a deposit of materials of any kind placed by artificial means.
Flash Flood Warnings mean flash flooding is occurring or imminent along certain streams and
designated areas.
Flood or Flooding shall mean a general and temporary condition of partial or complete
inundation of normally dry land areas caused by the overflow of inland waters and/or the unusual
and rapid accumulation or runoff of surface waters from any source.
Flood Forecasts means rainfall is heavy enough to cause rivers to overflow their banks or
melting snow is mixing with rainfall to produce similar effects.
Flood Fringe shall mean that portion of the floodplain between the floodway boundary and the
upper limits of the base flood. The flood fringe is the low hazard portion of a drainway channel
or watercourse outside of the floodway portion.
Flood Insurance Rate Map (FIRM) shall mean the official map on which the Federal Insurance
Administration has delineated both the floodplains and risk premium zones applicable to the
community.
Flood Insurance Study (FIS) shall mean the official report in which the Federal Insurance
Administration has provided flood profiles, as well as the Flood Boundary F000dway Map and
water surface elevation of the base flood.
Flood Profile means a graph showing the elevations of the floodwater surface and the elevations
of the underlying land as a function of distance along a path of flow.
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Floodplain shall mean the land in a drainageway within a community subject to a one-percent or
greater chance of flooding in a given year. The floodplain encompasses the flood fringe and the
floodway (conveyance zone).
Floodplain Administrator shall mean the duly appointed floodplain administrator of the
Stormwater Utility of the City of Fort Collins.
Floodplain Management shall mean the operation of an overall program of corrective and
preventative measures for reducing flood damage, including but not limited to emergency
preparedness plans, flood control works and floodplain management regulations. Floodplain
management refers to those activities that are implemented with the intent to promote the public
health, safety, and general welfare,to minimize public and private losses due to flood conditions,
and to maintain, enhance, and improve the natural and beneficial functions of floodplains.
Floodplain Management Regulations shall mean zoning ordinances, subdivision regulations,
building codes, health regulations, special purpose ordinances (such as floodplain ordinance,
grading ordinance and erosion control ordinance) and other applications of police power. The
term describes such federal, state, or local regulations, in any combination thereof, which
provides standards for the purpose of flood damage prevention and reduction.
Floodproofing shall mean a combination of structural provisions, changes or adjustments to
properties and structures subject to flooding, primarily for the reduction or elimination of flood
damage to properties, water and sanitary facilities, structures and contents of buildings in a
floodplain area.
Floodplain Use Permit shall mean any permit granted under the terms and conditions of City
Code Section 10 for development on land in a floodplain.
Flood Warning shall refer to forecasts of impending floods which describe the affected river,
the severity of flooding (minor, moderate or major) and when and where the flooding will begin.
Flood Watch shall refer to heavy rains (that may cause sudden'flash flooding in specified areas)
am occurring or forecast to occur. Understand that a flash flood can occur without any visible
sign of rainfall in the area.
Floodway shall mean the channel of a river or other watercourse in the adjacent lands areas that
must be reserved in order to discharge the base flood without cumulatively increasing the water
surface more than a designated height.
Habitable Floor shall mean any floor usable for living purposes which includes working,
sleeping, eating, cooking, recreation or a combination thereof. A floor used only for storage
purposes is not a habitable floor.
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Hydrology shall mean the scientific study of water, inland water, both surface and underground,
including its properties, phenomena, distribution, movement, and utilization.
Intended for Human Occupancy shall mean, as applied to structures, capable of and likely to
be used for residential habitation, or for commercial, industrial, or governmental occupation by
persons on a regular basis. Examples of structures normally not intended for human occupancy
include,without limitation, open air carwashes, unheated pavilions, barns and other agricultural
buildings, garden storage sheds, automatic teller machines, mausoleums and detached one and
two-car garages.
Lowest Floor shall mean the lowest floor of the lowest enclosed area(including basement),
except that an unfinished or flood resistant enclosure, usable solely for parking of vehicles,
building access, or storage, in an area other than a basement area, is not considered a building's
lowest floor; provided that such enclosure is not built so as to render the structure in violation of
the applicable non-elevation design requirements.
Natural and Beneficial Functions of Floodplains shall mean the functions associated with the
natural or relatively undisturbed floodplain that moderate flooding, retain flood waters, reduce
erosion and sedimentation, and mitigate the effects of waves and storm surges from storms and
ancillary beneficial functions, including maintenance-of waterquaiity, recharge-of groundwater,
and provision of fish and wildlife habitat.
New Construction shall mean those structures for which the start of construction commenced on
or after July 16, 1979, and includes any subsequent improvements to such structure.
Nonconforming Structure shall mean a structure which existed and was lawful before the
passage of the ordinance from which the Flood Prevention and Protection Article was derived,
but which is not in conformity with the requirements of said article.
NFIP refers to the National Flood Insurance Program.
Non-residential Structure shall mean any stricture or any portion of a structure used
exclusively for, or designed as and capable of being used for, office, commercial, business,
educational, public, industrial, or governmental occupation.
Obstruction shall mean any item or material not constituting a moveable object in, along,
across, or projecting into the floodplain that might impede, retard, or change the direction of a
flow of water, either by itself or by catching or collecting debris carried by such water, in a way
that would increase the flood hazard to adjacent properties.
Paleoflood Hydrology refers to the scientific study of past or ancient floods that occurred prior
to the time of(a) direct measurement by modern hydrologic procedures, or(b) documentation by
other human records.
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Reconstruction (repair of damaged structures) shall mean the rebuilding of an existing structure
which has been partially or completely destroyed by any cause (i.e., fire, wind, flood) without
increasing the floor area of the structure.
Regulatory Floodplain shall mean the floodplain that is regulated by the city, including the
Special Flood Hazard Area(SFHA). It covers areas identified by the City that are outside the
SFHA as mapped by the Federal Emergency Management Agency.
Regulatory Flood Protection Elevation shall mean an elevation of not less than eighteen(18)
inches above the base flood elevation.
Rehabilitation shall mean any improvements and repairs which are made to the interior and
exterior of an existing structure, but which do not result in any increase in the floor area of the
structure.
Residential Structure shall mean any structure or any portion of a structure that is used for, or
designed as and capable of being used for, the temporary or permanent domicile of persons,
including without limitation a dwelling, a boarding house, a hotel, a motel, and similarly used
structures.
Riparian Ecosystem refers to a distinct association of flora, fauna, and soil occurring along a
river, stream, or other body of water and dependent upon high water tables and occasional
flooding to maintain its viability. These areas often exhibit high biological productivity and
species diversity. Although riparian ecosystems are closely associated with a body of water, they
may extend beyond the Special Flood Hazard Area.
Special Flood Hazard Area (SFHA) shall mean the base floodplain delineation on a Flood
Insurance Rate Map. The SFHA is mapped as a Zone A. The SFHA may or may not encompass
all of a-community's-flood problems.
Start of Construction includes substantial improvement and shall mean the date the building
permit was issued, provided the actual start of construction,repair, reconstruction, rehabilitation,
addition placement, or other improvement was within 180 days of the permit date. The actual
start means either the first placement of permanent construction of a structure on a site, such as
pouring of slab or footings, the installation of piles,the construction of columns, or any work
beyond the stage of excavation; or the placement of a manufactured home on a foundation.
Permanent construction does not include land preparation, such as clearing, grading and filling;
nor does it include the installation of streets and/or walkways; nor does it include excavation for
a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include
the installation on the property of accessory buildings, such as garages or sheds not occupied as
dwelling units or not part of the main structure. For a substantial improvement, the actual start of
construction means the first alteration of any wall, ceiling, floor or other structural part of a
building, whether or not that alteration affects the external dimensions of the building.
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Structure shall mean any walled and roofed building, manufactured home or a gas or liquid
storage tank that is principally above ground.
Substantial-improvement shall mean any combination of repairs, reconstructions,-
rehabilitations, additions, or other improvement of a structure,taking place during the life of the
structure,the cost of which equals or exceeds fifty percent of the market value of the structure
before the start of construction of the improvement. This term included repairs to structures that
have incurred substantial damage, regardless of the actual repair work performed. The term does
not,however, include either:
(1) Any project for improvement of a structure to correct existing violations of
state or local health, sanitary, or safety code specifications which have
been identified by the local code enforcement official and which are the
minimum necessary to assure safe living conditions or
(2) Any alteration of a historic structure, provided that the alteration will not
preclude the structure's continued designation as a historic structure.
Watercourse shall mean a stream, creek, pond, slough, gulch, reservoir, lake or portion of the
floodplain functioning as a natural or improved channel carrying flows,not constituting a flood.
The term includes without limitation established natural and human-made drainage ways for
carrying storm runoff but does not include irrigation ditches.
Zone A refers to the Special Flood Hazard Area shown on a community's Flood Insurance Rate
Map. There are five types of A Zones:
A: SFHA where no base flood elevation is provided.
A#: Numbered A Zones (e.g., A7 or A14), SFHA where the FIRM shows a base flood
elevation in relation to National Geodetic Vertical Datum (NGVD).
AE: SFHA where base flood elevations are provided. AE Zone delineations are now
used on new FIRMS instead of A#Zones.
AO: SFHA with sheet flow, ponding, or shallow flooding. Base flood depths (feet
above grade) are provided.
AH: Shallow flooding SFHA. Base flood elevations in relation to NGVD are provided.
Zone B refers to the area of moderate flood hazard, usually depicted on Flood Insurance rate
Maps as between the limits of the base and 500-year floods. B Zones are also used to designate
base floodplains of little hazard, such as those with average depths-ofiess-fir i foot.
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Zone C refers to the area of minimal flood hazard, usually depicted on FIRMs as above the 500-
year flood level. B and C Zones may have flooding that does not meet the criteria to be mapped
as a Special Flood Hazard Area, especially ponding and local drainage problems.
Zone D refers to an area of undetermined but possible flood hazard.
Zone X Newer FIRMS show Zones B and C (see above) as Zone X.
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II. PURPOSE
The purpose of these floodplain administration and management guidelines are to recommend
and clarify policies and procedures for use by the City of Fort Collins in interpreting and
implementing City of Fort Collins Code, Chapter 10, Flood Prevention and Protection, Article
II.,Flood Hazard Areas, and the requirements of the National Flood Insurance Program(NFIP)
(44 CFR 60).
It is also the purpose of this plan to promote the public health, safety, and general welfare,to
minimize public and private losses due to flood conditions, and to maintain, enhance, and
improve the natural and beneficial functions of floodplains by the development and
implementation of floodplain management activities. It is the purpose of this document to have
all relevant information on the management and regulation of City floodplains in one place.
III. OBJECTIVES
The objectives of the floodplain administration and management guidelines are to:
1. Establish and clarify City of Fort Collins policy and procedure for the administration and
management of activities in floodplains which are consistent with the Comprehensive
City Plan's goals and policies, City Code, State regulations, and the National Flood
Insurance Program;
2. Identify and implement floodplain management activities which minimize the risk to life
and property in floodprone areas, increase public awareness of the local flood hazard,
and which maintain, enhance, and improve the natural and beneficial functions of
floodplains;
3. Provide guidance for managing activities which result in the modification or occupation
of floodplains, or which result in impacts to the natural and beneficial functions of
floodplains;
4. Identify and define the flood hazard and information required to evaluate hazards
associated with the modification or occupation of floodplains.
IV. BENEFITS
By collecting all the adopted value statements,policies, regulations, and guidelines for
floodplains within the City of Fort Collins into one place, compatibilities and conflicts among
community values, local ordinances, and state and federal laws are identified. The goal is to
clarify and understand what existing plans and regulations say about the City's floodplains and to
meet the intent of the elements of the Comprehensive Plan by providing guidance in the
interpretation and implementation of the various policies and regulations at the local level. In
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addition, because rivers, streams, and associated floodplain systems have been identified as an
important resource to the City of Fort Collins,the establishment of a focused floodplain
management program will benefit the residents of Fort Collins through reduced loss of property
and life, increased awareness of the flood hazard, balanced management of the environment and
economic development of floodplain lands, and reduced flood insurance premiums.
V. FLOODPLAIN POLICY
It is the floodplain management policy of the City of Fort Collins to minimize potentially
hazardous conditions associated with flooding,to recognize and manage for the preservation of
floodplain values, to adhere to all City mandated codes,policies, and goals, and to comply with
all State and Federally mandated laws and regulations related to the management of activities in
floodprone areas. Specifically, it is the policy of the City of Fort Collins to:
1. To recognize and manage floodplains with the intent to provide a balance between the
environmental protection and economic development of floodplain lands.
2. To minimize risk to life and property by structural and non-structural design or
modification of actions in the floodplain where it is not otherwise practical to place
structures and human activities outside of the floodplain;
3. To recognize that maintenance, restoration, and enhancement of the natural resources and
the beneficial functions of floodplains is a concurrent goal with reducing human
vulnerability to flood damage;
4. To require structures and facilities which must be in the floodplain to be designed so as to
be consistent with the intent of the Standards and Criteria of the City of Fort Collins and
the National Flood Insurance Program.
The standards and criteria of the City of Fort Collins and the National Flood Insurance
Program pertain specifically to this plan. Those Standards and Criteria are directed
towards the protection of structures and facilities from flood hazards and the protection of
existing development from the effects of new development. The standards pertain to the
siting and design criteria for residential and non-residential structures, utility systems, and
other structures. These standards will apply to all City planning, assessment, and design
activities for actions in the floodplain.
5. To educate the public to the hazards of flooding and to develop and disseminate the most
accurate information obtainable on the local flood hazard.
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VI. NATIONAL FLOOD INSURANCE PROGRAM AND POLICY
The National Flood Insurance Program (NFIP)was created by Congress to reduce the mounting
losses of life and property from floods. The National Flood Insurance Program emphasizes the
importance-of managing the-Nation's floodplains-in-order to:educe flood hazards. The-intent-of
the Program is to encourage only that development which minimizes flood damage and potential
increases in flood levels. The NFIP regulations therefore establish minimum floodplain
management standards for designated flood-prone communities.
The National Flood Insurance Act of 1968 (P.L. 90-448) established the program within the
Federal Insurance Administration(FIA) of the department of Housing and urban Development.
This Act established the principle of providing federally subsidized flood insurance for existing
structures in return for local government adoption and enforcement of floodplain management
measures to reduce or avoid future-floadlosses.
The Flood Disaster Protection Act of 1973 (P.L. 93-234) substantially strengthened the program
by increasing the amounts of insurance available and making the purchase of flood insurance
mandatory for loans by Federal Agencies in communities participating in the National Flood
Insurance Program.
Title V. of the Riegle Community Development and Regulatory Improvement Act of 1994 (P.L.
103-325) makes numerous changes and strengthens the NFIP through revisions including
mitigation insurance and funding, disaster assistance, lender compliance,mapping, flood
insurance waiting period requirements, and community rating system and incentives for
community floodplain management. Many of the recent changes to the NFIP include a
recognition of the importance of the natural environment and recognition of the inherent risk of
living in floodprone areas with or without flood control structures.
The NFIP provides the design,performance, and elevation standards that communities must
enforce in flood hazard areas. These standards relate to the degree of potential flood damage
within the local jurisdiction determined by the technical data developed by the FIA for use by
individual communities. Communities may satisfy the requirements in one of several ways,
including adoption of a single-purpose ordinance, amendment of existing ordinances and codes,
or revision of a multipurpose ordinance.
The City of Fort Collins has adopted a comprehensive single-purpose ordinance, City of Fort
Collins Code, Chapter 10, Flood Prevention and Protection, Article II., Flood Hazard Areas, to
comply with all of the Program requirements (Appendix I).
Flood Insurance
Flood insurance is a form of casualty insurance which provides protection to property owners
who may incur losses from a flood. This coverage provides a property owner with a direct means
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to recover financial losses. The NFIP, administered by FEMA, provides the basis for a large part
of the federal government's role in floodplain management.
In exchange for assuring available and affordable flood insurance in a given community,the
Federal Government requires that the local government meet certain conditions. The first
condition is that the community use Federally approved floodplain delineation information,the
most restrictive information, or the best information available, in making floodplain use
decisions. The second, and major, condition is that the community initiate and maintain a permit
system for development in the floodplain and that the community adopt and enforce floodplain
management regulations which meet Federal standards. Those management aspects of the NFIP
are aimed at curtailing ever increasing annual national flood damages and reducing the total
annual national disaster relief expenditures.
Potential consequences for not meeting those conditions are loss of any Federally connected
mortgage loans, grants, or other funding for development in floodplain areas of the community,
denial of disaster relief funds for flood damages, and suspension from the NFIP, making property
owners in the community ineligible for flood insurance.
The Galloway Report
The White House Interagency Floodplain Management Review Committee has released (1994)
"Sharing the Challenge: Floodplain Management into the 21st Century" (The Galloway Report).
The report is expected to have the single largest impact on national floodplain management
policy since the 1930's and affirms the nation's need and ability to balance the environmental
protection and economic development of our floodplain lands. The Committee's report proposes
a way to manage the floodplains of the nation, replacing the past reliance on structural solutions
with a sequential strategy of avoidance of the flood risk as much as possible, minimizing the risk
when and where it cannot be avoided, and mitigating the impacts on individuals and
communities when floods,do occur. Two ofthe most pertinentconclusions-with_r Bard to the
impact on local community floodplain management are;
i. Preservation and enhancement of the natural resources and functions of
floodplains must be a goal concurrent with reducing human vulnerability to flood
damage; and;
ii. State and local governments must manage the floodplains.
VII. STATE OF COLORADO FLOODPLAIN LEGISLATION
The focus of State and Federal legislation has been to leave a role for local governments to
establish local floodplain management programs. Federal legislation provides local governments
with several kinds of assistance, i.e., Army Corps of Engineers projects and technical assistance,
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and it specifies some conditions local governments must meet to receive such assistance. It
leaves responsibility for managing floodplains with local government.
Similarly, Colorado legislation also creates floodplain management programs and provides local
governments with the authorities for floodplain management but has left the responsibility for
managing floodplains with local governments. The concept of the 100-year floodplain was first
adopted by the State of Colorado as part of Section 24-65-105, 1973, as amended, whereby the
Colorado Land Use Commission was charged with designating critical areas in the state where a
one hundred-year(storm return frequency) floodway should be identified...." Section 24-65.1-
103 defined a floodplain as an area "subject to flooding as a result of the occurrence of an
intermediate regional flood...." Section 24-65.1-403(3)(b)requires designation and approval of a
floodplain by the Colorado Water Conservation Board(CWCB)prior to regulation by a local
government.
VIII. COMPREHENSIVE CITY GOALS, OBJECTIVES,AND POLICIES
In order to have an effective floodplain management plan for the City of Fort Collins it is critical
to ensure consistency with the overall goals, objectives, and policies of the elements of the City
of Fort Collins Comprehensive Plan. The Fort Collins Comprehensive Plan is an official public
document adopted by the City Council as a policy guide to decisions concerning the physical,
social, economic, and environmental development of its area.
The Fort Collins Comprehensive Plan(Plan) is not a single document. It is a compilation of
policy documents and area plans that have been adopted, over time, as "elements" of the
Comprehensive Plan. The abundance of Plan policy is consistent on a surface level, however,
there are inconsistencies in coordinating the intentions of some of the adopted plans with regard
to floodplain management and administration. It is a goal of these Floodplain Administration and
Management Guidelines to meet the intent of the elements of the Comprehensive Plan and to
provide guidance in the interpretation of apparently conflicting recommendations and policies.
For example,the "Goals and Objectives" includes a recommendation to discourage development
within the floodplain areas of Spring Creek, Fossil Creek, Dry Creek, and other drainageways
such as the Cache La Poudre River. The "Landuse Policy Plan" states that certain uses may
locate in less hazardous floodplain classifications provided proper mitigation of the flood hazard
and water quality is preserved and the floodplain is protected consistent with the City's Open
Space Plan and the entire project is approved by the City. Although these are somewhat
conflicting recommendations, both plans do make additional recommendations with regard to
requiring development within the less hazardous floodfringe classifications only be allowed with
modifications which mitigate the flood hazard. The method of"discouraging" development
within a floodplain is not specifically addressed in either plan, but may be interpreted as
compliance with specific floodplain design requirements or modifications.
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All policy decisions by the City Council, or any of its advisory boards and commissions, as well
as the day-to-day decisions within individual governmental departments of the City, should be in
conformance with the intent of the City's goals and objectives. The City Comprehensive Plans
goals, objectives, and policies pertain specifically to this plan for the management of actions in
the floodplain.
Mandated goals, objectives, and policies that pertain to floodplain management for the City of
Fort Collins are as follows. The goals, objectives, and policies are simply restated as they were
originally written in the respective documents and only those statements that affect floodplains
and floodplain management are stated.
1. Goals and Objectives: An Element of the Comprehensive Plan of the City of Fort
Collins, August 1977, amended 1991. The Goals and Objectives are not binding
statements and are not meant to have the force of law. They are intentionally general in
nature in order to allow the flexibility of several different methods for achieving them.
a. Limit residential development in natural hazard areas or require construction
modifications which would mitigate natural hazards.
b. Provide information to the public as to types and location of natural hazard areas.
C. Encourage joint use of drainage facilities, such as open channels and detention
ponds, for open space purposes.
d. Encourage land use planning which will protect new and existing development
from flood hazards.
e. Discourage development within the floodplain areas of Spring Creek, Fossil
Creek, Dry Creek, and other drainageways.
f. Encourage open channel drainageways whenever possible.
g. Incorporate detention of stormwater runoff to minimize costs and downstream
flood hazards.
h. Encourage the development of storm drainage facilities which will protect the
older portions of the city from increased flood hazards resulting from new
development.
i. Consider long-range ecological effects and costs when addressing short-term and
long-term economic problems.
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j. Insure that the type, design, and location of new development be compatible with
environmental considerations.
k. Insure proper watershed management.
1: Capitali a upon-the location ofthe Poudre- iver-and_utilize-it_asan_asset irLthe-
development of recreational and open space areas in the older City.
M. Coordinate and upgrade disaster prevention in the area.
2. Land Use Policies Plan, City of Fort Collins Comprehensive Plan, Landuse element,
August 14, 1979, amended 1990. The land use policies represent the official public
policy guidelines concerning landuse matters and land use related decision-making by the
City of Fort Collins. These policies establish the City land use policy on how to handle
development proposals in floodplain areas.
a Flood prone areas of streams and rivers in the city shall be designated as
"floodplain management areas" and special development standards applied
therein.
b. The City shall coordinate with the County in flood control, water quality and
urban runoff programs to realize the greatest benefit from all of these programs.
C. The city shall prohibit any residential development in areas which have been
officially designated as floodway areas.
d. Within the floodway, as defined by Federal Insurance Administration studies,
adopted by the City, the City shall encourage light recreational and open space
uses and will allow extractive industrial and agricultural uses.
e. Development within the less hazardous floodfringe classifications shall only be
allowed with modifications which mitigate the flood hazard.
f. If flood control measures are provided so as to mitigate the flood hazard, the
floodplain management classification and appropriate requirements shall be
removed.
g. Industrial uses may locate in less hazardous floodplain classifications provided
proper mitigation of the flood hazard and water quality is preserved and the
floodplain is protected consistent with the City's Open Space Plan and the entire
project is approved by the City.
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h. Neighborhood service centers may locate in less hazardous floodplain
classifications provided proper mitigation of the flood hazard is provided and the
floodplain is protected consistent with the City's Open Space Plan and the entire
project is approved by the City.
i. Regional/community shopping centers may locate in less hazardous flood fringe
classifications provided proper mitigation of the flood hazard is provided and the
floodplain is protected consistent with the City's Open Space Plan and the entire
project is approved by the City.
j. Areas along the Poudre River, Spring Creek, and Fossil Creek should be
incorporated into the City's parks and recreational trail system.
k. Consistent with a fiscal impact analysis and effects on the Capital Improvements
Program the City should acquire and utilize the officially designated floodways
of the Poudre River, Spring Creek, and Fossil Creek for open space.
1. The City should protect the scenic and recreational value of the City's lakes,
rivers, and streams from encroachment by incompatible uses.
in. Adequate public access to the City's lakes, rivers, and streams should be
maintained.
3. Natural Areas Policy Plan,Natural Resources Division, October 1992. The intent of this
plan is to set a direction for the future management of natural areas in Fort Collins. The
Plan specifically identifies the Poudre River, Fossil Creek and tributaries, Spring Creek,
Cooper Slough, Boxelder Creek, and Dry Creek and identifies and describes important
natural resources and systems present in these river corridors. The plan emphasizes
opportunities to restore and enhance degraded habitats, and to increase recreational and
educational use of river resources. The plan calls for coordination with other city
departments and programs to acquire key natural areas, including stormwater
mnn gpmg nr sites and reclaimed gravel mines.
4. Parks and Recreation Master Plan, Parks and Recreation, February 1988. The plan
aims to assure the maintenance of the existing parks, recreation and open space system in
light of continuing population growth, the desire to add new facilities, and new financial
demands.The plan's natural resources inventory and mapping identify the Poudre River
as the most significant riparian area and wildlife habitat in the community and
recommends the acquisition of additional open space areas along the river, including
reclaimed gravel mines. The plan recognizes the role of all floodplain lands for open
space and the maintenance of wildlife habitat.
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5. Framework for Environmental Action for the City of Fort Collins,Natural Resources
Division, January 1992. The framework has three purposes; a)to summarize current
environmental management responsibilities and programs within the City;b)to identify
steps needed to improve environmental management in the future; and, c.)to recommend
an ongoing Action Plan for a comprehensive review of environmental management
policies and activities of the City of Fort Collins.
The Framework Action Plan recommends two tasks with regard to Development Hazard
Areas, such as floodplains, for the review and improvement of the environmental
policies,plans-, and programs ofthe City of Fort Collins;_
i. Update the development hazards maps for the Urban Growth Area,
showing such areas as floodplains.
ii. Evaluate the adequacy of existing standards which guide development in
proximity to development hazard areas. Adopt revisions to zoning codes
and Land Development Guidance System (LDGS) if changes are required.
6. Poudre River Land Use Framework, Cultural, Library and Recreation Services. The
purpose of this project is to assess existing Comprehensive Plan elements and other
documents to determine what actions are necessary to unify planning efforts along the
Poudre River corridor. Over 20 elements of the Comprehensive Plan were reviewed and
compiled with regard to the Poudre River corridor and one of the common themes in all
the plans identified the river as an important factor in the quality of life in the Fort Collins
region.
The report identifies sub-areas along the Poudre River corridor. The intent of identifying
sub-areas is to recognize that the river corridor is a chain of distinct, smaller settings and
systems that function interdependently as the whole. The sub-areas may become the basis
for future river corridor planning efforts to create specific, site-oriented expectations for
land use and resource management.
The report also specifically identifies that"the management of flood hazards is
recognized as a fundamental public safety value, with implicit understanding that an
effective flood[plain]-management-program must bein-place-in-order-to-keep the
environmental, socio-cultural and economic values of the river corridor."
Data and informational gaps are identified. Of particular significance is that there is no
strategic approach to deal with the influence of gravel extraction from the river corridor.
There are an estimated 3,200 acres of land currently permitted for gravel extraction
within Fort Collins urbanizing area. There is also no existing policy on how to treat the
issue of river capture by existing gravel pits.
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The Poudre River Landuse Framework summarizes existing comprehensive plan
elements as based on "consistent river values" and"specialized river values". Consistent
river values include; recreation,parks,trails and access to the river, floodplain and flood
hazard management, instream flow management,natural areas and wildlife habitat, open
space acquisition and preservation, and, allowance for or management of development
proximate to the river. Specialized river values include; education,research and
interpretation about natural and cultural resources, cultural development and
enhancements,historic resources preservation, and scenic, aesthetic, and design
enhancements.
7. Watershed Approach, City of Fort Collins, Stormwater Utility. The Fort Collins City
Council adopted a framework document titled "Stormwater Quality: A Watershed
Approach." The approach is to look at the entire urban watershed and use appropriate
techniques to prevent pollution where possible;treat or mitigate polluted runoff from the
urban landscape; and to protect and restore aquatic, wetland and stream side habitat
where practicable. This framework will set the vision for changes in the utility's
approach-to-public-involvement_and education, stormwater design criteria and
construction standards, and drainage master planning. The relationship of this document
to floodplain administration is to incorporate an assessment of the natural and beneficial
functions within the floodplain into the Utilities work.
IX. FLOODPLAIN ADMINISTRATOR'S POWERS AND DUTIES
The duties and responsibilities of the Floodplain Administrator shall include but are not limited
to (Code Section 10-36):
1. Reviewing all floodplain use permits to determine that the permit requirements of City
Code, Section 10 have been satisfied. The administrator will review all proposed
development within all floodplains in the City for compliance with the City standards and
comprehensive policies, and compliance with the NFIP. In reviewing an application,the
key is that the proposed activity itself must be safe from flooding and it must not increase
the flood hazard to other areas. In addition, the degree of impact to the natural and
beneficial functions of the floodplain may be assessed on a case-by-case basis to
determine the degree of acceptable impact which may be associated with proposed
floodplain development. Impacts to natural functions will be assessed by the applicable
City departments such as Natural Resources,Parks and Recreation, and Stormwater .
Utility.
2. Advising the applicant prior to the issuance of a floodplain use permit that other
necessary permits may need to be obtained from federal, state or local government
agencies. Conditional floodplain use permits may be issued contingent upon receipt of
other specifically identified federal, state or local government agency permits of approval.
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The Floodplain Administrator should be able to tell the applicant when an additional
permit might be required, such as a U.S. Army Corps of Engineers 404 Wetlands Permit.
3. Reviewing all floodplain use permits to determine if the proposed development is located
in the floodway and, if located in the floodway, assuring that the encroachment
provisions of City Code, Section 10 are met. A permit may not be issued unless the
applicant can demonstrate to the satisfaction of the Administrator that the development
will not increase flood heights. Usually such developments are limited to open space for
recreation,parking, or agriculture.
4. Requiring the obtaining and recording by a professional engineer or land surveyor the
actual elevation in relation to mean sea level of the lowest habitable floor including
basement of all new or substantially improved structures and whether or not the structure
contains a basement.
5. Requiring for all new or improved floodproofed structures; a) verification and recording
by a professional engineer or land surveyor of the actual elevation in relation to mean sea
level; and,b) Maintenance of the floodproofing certifications.
6. Maintaining for public inspection all records pertaining to the provisions of City Code,
Section 10. Records include permits issued, inspections made, appeals, and other official
actions.
7. Notifying adjacent communities and the CWCB prior to any alteration or relocation of a
watercourse and submitting evidence of such notification to the Federal Insurance
Administration. The Floodplain Administrator will review all development permit
applications that include a watercourse alteration. The Floodplain Administrator must be
satisfied that the flow-carrying capacity of the water course will not be diminished. The
Applicant must demonstrate to the satisfaction of the Administrator that the hydraulic
capacity, channel stability, and upstream and downstream reaches will not be adversely
affected by the watercourse alteration.
8. Requiring that maintenance is provided within the altered or relocated portion of the
watercourse so that the flood-carrying capacity is not diminished
9. Making interpretations, where needed, as to the exact locations of the boundaries of
floodplains, for example, where there appears to be a conflict between the map boundary
and actual field conditions. The interpretation may be based on topographic,hydrologic,
hydraulic, geomorphic, sedimentologic, and botanic indicators. The person contesting the
location of such boundary shall be given a reasonable opportunity to appeal the
interpretation as provided by the variance procedure outlined in City Code Section 10.
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X. ADMINISTRATION OF FLOODPLAIN REGULATIONS
Appendix I contains the adopted City Code Section 10, Flood Prevention and Protection that
form the basis of the City regulatory program for floodplain administration. The following
section describes a model process to guide the local administration of floodplains within the City
of Fort Collins. The interpretation and application of the article are considere&uriirimuur
requirements and applies to all federal and local floodplains within the jurisdiction of the city.
Development Proposal
Conceptual Review The Development Review Manager at the Stormwater
Department will confer with the Floodplain Administrator
to determine whether the proposed development falls
within a floodplain shown in the Master Plans and/or
FEMA FIRM. If not, floodplain issues are no longer a
concern. If so,the rest of the process applies.
Preliminary Development
Review The Floodplain Administrator will require that the
applicant make a determination as to whether the project is
located in a floodway, a flood fringe, or (shallow flooding
or ponding) floodprone area which is identified in the
Drainage and Erosion Control Report and Plans.
Detailed Development
Review If the proposal is in an area where detailed information is
available,the applicant will provide the Floodplain
Administrator with-I00-year flood elevations. If he-
proposal is in an area where detailed information is not
available, the applicant will provide a professionally
prepared study ("professionally prepared" means the study
has been prepared by a Professional Engineer registered in
the State of Colorado using methodologies acceptable to
FEMA,the City of Fort Collins, and the CWCB)that
presents the detailed information. If any of the activities
proposed would change the 100-year floodplain,the
submittal materials will qualitatively and quantitatively
describe he floodplain as it would appear before and after
construction.
The Floodplain Administrator will review the information
for accuracy. The review will determine whether any
prohibited uses are proposed in the floodway. It will also
determine whether any prohibited uses are proposed in the
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flood fringe or whether any proposed conditional uses fail
to meet the required standards, especially standards for
lowest floor elevations.
The Floodplain Administrator, with consultation from other
City departments, will visit the site to confirm existing site
topographic, ecologic, and geomorphic conditions with
regard to floodplain delineation and proposed development.
The Floodplain Administrator will make recommendations,
as necessary, to eliminate buildings, relocate them, elevate
them,protect them, or otherwise modify the design. The
Floodplain Administrator, with the assistance of other City
Departments, will assess any potential impacts to the
natural and beneficial functions of the floodplain and make
recommendations for plan modification as required.
In some cases a development may be located in an area that
is documented as two different floodplain hazard
classifications on the Stormwater Department Master Plan
Map and the FIRM. Whichever flood hazard classification
map is more restrictive has precedence for development
review and design. In such cases, the FIRM is used to
determine flood insurance purchase requirements for
compliance with the NFIP.
Development Approval
or Denial Anyone wishing to develop in the floodplain must obtain a
Floodplain Use Permit application form from the
Floodplain Administrator and submit it for evaluation, and
receive approval, before beginning any development
activities.
Once the design modification recommendations are
adequately addressed, the applicant will apply for a
Floodplain Use Permit from the Floodplain Administrator
which provides information about the 100-year flood
elevations and the lowest floor elevations proposed to be
built, signed by a registered professional engineer,
surveyor, or geologist.
The Administrator will determine if the proposed
development is consistent with and complies with all City
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Inances. The permit will be
:d on compliance. If the permit is
I
y appeal the determination to the
A Building Permit will not be
Main Use Permit.
Start of Construction strator will visit the site during
that all floodplain management
:t, i.e., elevation requirements.
Completion of
Construction :en completed, the applicant will file
for each structure to the Floodplain
l by a professional engineer,
wilt" lowest floor elevations have
n of eighteen(18) inches above the
residential structures. Commercial
.proofed or elevated to the same
Certificate of
Occupancy pment, any changes have been made
zin that results in changes in the
ns or changes in the area that would
ar flood, the Floodplain
ew for compliance that the
a describing the revised floodplain is
n maps will then require revision
procedures, i.e., FEMA map
XI. CONSIDERATIC TRMITTING
1. General statemen[ agement;
a. Developm sins should be avoided unless it is
considered andpoint and unless no suitable
alternative _ isily defined and may require
determine, nce of development in floodway is
the preferr to people,property and natural
floodplain
b. Existing and new developments should be treated differently. For much of the
existing development, consideration should be given to appropriate modification
of the flood hazard and restoration of floodplain values.In contrast,proposed
development and new uses should be carefully regulated to insure the compatible
development of floodplains by minimizing the hazards present and managing for
the natural floodplain values and functions.
C. An acceptable degree of hazard differs with the type of floodplain use. Selected
uses are or can be made compatible with certain flood characteristics.
d. An acceptable degree of environmental impact differs with the location in the
floodplain along a river corridor. Selected uses are or can be made compatible
with certain floodplain characteristics. Long-term and short-term impacts must be
considered.
e. Consideration should be given to all tools to modify human occupancy of
floodplains (nonstructural measures) and to modify flooding (structural measures)
in seeking to manage flood losses and floodplain values. Some combination of
these tools is often the desirable management strategy.
2. City Code, Section 10-37 describes the required information for the issuance of a
floodplain use permit (see standard Fort Collins form).
a. Elevation in relation to mean sea level of the lowest floor, including basement, of
all structures;
b. Elevation in relation to mean sea level to which any structure has been
floodproofed;
C. Certification by a registered professional engineer or architect that the
floodproofing methods for any non-residential structure meet the flood proofing
criteria in the Article;
d. Description of the extent to which any watercourse will be altered or relocated as
the result of proposed development.
3. The following information may also be required to adequately determine conformance
with the floodplain use permit application.
a. The written consent of the owners of all property subject to the development
request;
b. A written statement addressing the criteria for approval;
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C. A surface view plan showing elevations and contours of the ground; pertinent
structures, fill, and storage elevations; sizes, locations, and spatial arrangement of
all proposed, anticipated, and existing structures and landscaping on the site;
location and elevations of streets, water supplies and sanitary facilities, and soil
types; and,
d. Specifications for building construction and materials, filling, dredging, grading,
channel improvements and changes, storage of materials,water supply, and
sanitary facilities.
4. The Administrator may require the applicant to furnish additional information and details
deemed necessary to evaluate the effects of the proposed construction upon the
floodplain, including:
a. Valley cross-sections showing the floodplain surrounding the watercourse, cross-
sections of the area to be occupied by the proposed development, and 100-year
flood maximum water-surface elevation information;
b. A profile showing the slope of the bottom of the channel or thalweg of the
watercourse;
C. A floodplain analysis of the flood profile, elevation, and velocity,using
methodology acceptable to FEMA and the City of Fort Collins, including existing
and anticipated uses and making a determination that the proposed construction or
development will not cause a rise in the elevation of the water-surface of the 100-
year flood;
d. A structural analysis by a Colorado Registered Professional Engineer showing
that any proposed structures will be adequately designed and constructed to
prevent floatation, collapse, or lateral movement of the structure resulting from
hydrodynamic and hydrostatic loads, including the effects of buoyancy and
scouring.
e. Studies to demonstrate/document impact or no-impact to the natural and
beneficial functions of floodplains.
5. When reviewing the application for a floodplain use permit,the Administrator shall
determine which portions of the floodplain are affected by the particular development
request and then shall apply the provisions of this article as applicable. The Administrator
also shall determine whether the application meets the intent of Section 10 after
considering the following factors:
a. The effects upon the efficiency or capacity of the conveyance zone;
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b. The effects upon lands upstream, downstream, and in the immediate vicinity;
C. The effects upon the one hundred year flood profile and channel stability;
d. The effects upon any tributaries to the main stream, drainage ditches, and any
other drainage facilities or systems;
e. Whether additional public expenditures for flood protection or prevention will be
required;
f. Whether the proposed use is for human occupancy;
g. The potential danger to persons upstream, downstream, and in the immediate
vicinity;
h: `Whether any proposed changes in watercoursewill have an adverse
environmental effect on the watercourse, including without limitation, erosion of
streambanks and streamside trees and vegetation and wildlife habitat;
i. Whether any proposed water supply and sanitation systems and other utility
systems can prevent disease, contamination, and unsanitary or hazardous
conditions during a flood;
j. Whether any proposed facility and its contents will be susceptible to flood
damage and the effect of such damage;
k. The relationship of the proposed development to the Elements of the City of Fort
Collins Comprehensive Plan and any applicable floodplain management
programs;
1. Whether safe access is available to the property in times of flood for ordinary and
emergency vehicles;
M. Whether the cumulative effect of the proposed development with other existing
and anticipated uses will increase flood heights; and,
n. Whether the expected heights, velocities, duration, rate of rise, channel stability
and sediment transport of the floodwaters expected at the site will adversely affect
the development or surrounding property.
o. Whether hazardous materials will be susceptible to flood waters.
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6. If the Administrator determines that the applicant meets the purposes and-requirements of
City Code, Section 10, the Administrator shall issue the permit and may attach such
conditions as deemed necessary to further the purposes of this chapter.
XII. FLOODPLAIN COMPLIANCE AND ORDINANCE ENFORCEMENT
It is important for the City of Fort Collins to ensure that floodplain regulations are enforced; both
from the standpoint of meeting State and Federal regulations, and providing protection to the
residents of Fort Collins. Although one violation may not be perceived as causing a significant
increase in damages,the cumulative effects can be devastating. In addition,by allowing
violations to go unabated,the enforcement of future violations may be difficult based on past
precedence.
The legal basis for regulating floodplains is found in Federal Regulations, State Statutes and
Rules, and local ordinances including the NFIP, Colorado Revised Statutes, and Fort Collins City
Code. The local ordinances are designed to protect new buildings and prevent increased flood
damage to existing structures. For this reason, City ordinance places greater restrictions on
development within floodplains than would normally be found in other portions of the
community; and, in fact, regulates a wider variety of activities than may be regulated in the
remainder of the community.
Floodplain development activities fall into 6 general categories; filling, grading, excavating,
construction, storage, and public health activities. It is important to know what constitutes each
of these activities and the impact of activities which do not meet the requirements of the City
ordinance.
Filling is the act by which a piece of land is built-up by the placement of earth, gravel, or
man-made substance. By placing fill within a floodplain, the capacity of the floodplain to
store water is reduced. In addition, filling may block the conveyance of the floodplain,.
forcing natural flow which was formerly confined to the floodplain or channel to seek a
new route (causing new or increased damages).
Grading or regrading is the act of sloping or resloping the ears surface. It may be for
the purpose of creating hills or berms or sloping the land for positive drainage. While
regrading normally does not,affect storage, it can block conveyance. In addition,
regrading,which is done for the purpose of removing meanders or smoothing out the
channel bottom, may cause velocities to increase on the stream. Increased velocities can
lead to both increased damages to buildings and structures downstream of the site, and
endanger the lives of those people who happen to enter the floodplain. In addition,
increased velocities can cause increased erosion downstream.
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Excavating is the act of removing or scooping out a portion of the floodplain. Excavating
may include removing the soil completely from the floodplain or depositing it in another
portion of the floodplain. If the borrow material was placed in another portion of the
floodplain, conveyance could be affected. In addition, the excavation could affect erosion
and water quality.
Construction may include; 1)construction, reconstruction,repair, placement, or
replacement of a building or any addition to a building; 2)installing a manufactured
home on a site or installing a travel trailer on a site; 3) drilling, mining, installing utilities,
construction of roads, bridges-orsumiarprojects; 4) construction of'evees,walls, and
fences; and, 5)habitat restoration and enhancement. Any of these activities could
adversely affect flood conveyance, flood storage,building protection, and structural
integrity.
Storage of materials includes locating, either inside or outside of a building, supplies or
materials below the flood protection elevation. Of particular significance to regulate is
chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids,
pollutants, and other hazardous or toxic materials.
Public health activities include those activities designed to protect water supply and
waste disposal systems. This includes protecting wells or water supply systems from
infiltration by elevating or sealing manholes or other openings into the system. It also
includes protecting well or septic systems both from infiltration and from contaminating
the flood waters.
Preventing increased damage is one of the objectives of the City floodplain regulations. In order
to accomplish this objective, any type of activity which could block or divert water, increase
velocities or send flood waters onto properties that would not otherwise be flooded must be
regulated.
XIIL SUBSTANTIAL IMPROVEMENT POLICY
The following policy better defines the administration of the City Code Section 10-22, with
regard to determination of substantial improvement for all FEMA and City designated
floodplain within the City of Fort Collins.
Substantial improvement is defined as any combination of repairs,reconstructions,
rehabilitations, addition, or other improvement of a structure, taking place during the life of the
structure,the cost of which equals or exceeds fifty percent of the market value of the structure
before the start of construction of the improvement. This term included repairs to structures that
have incurred substantial damage, regardless of the actual repair work performed.
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SUBSTANTIAL IMPROVEMENT = COST OF IMPROVEMENT = 50% OR MORE
-----------------------------------
MARKET VALUE
Market value is for the structure only, not the land. A substantially improved/damaged structure,
or substantial addition to a structure, is required to comply with all applicable floodplain
regulations. Market value of the existing structure is determined prior to any improvement and
based on the most current market values at the time of application. The total cost of the
improvement must also be determined.
In order to provide for uniform administration of floodplain regulations in Fort Collins,the
following procedure for determining market value of an existing structure is recommended.
1. The Larimer County Tax Assessment for the structure is used for determining market
value. Using the tax assessment should result in a conservative estimate of market value
for the determination of substantial improvement.
2. Alternately, the applicant may provide a determination of the market value of the existing
structure by a professional appraiser. The cost of appraisal is the responsibility of the
applicant.
The following definitions apply to three general types of alterations that are impacted by
substantial improvement.
Additions are defined as an alteration to an existing structure which results in any increase in the
structures floor area. If an existing structure in the floodplain is physically enlarged and the cost
of the enlargement equals or exceeds 50%of the market value of the structure before
enlargement, then the existing structure is considered to have been substantially improved and is
subject to City Code and NFIP requirements (i.e., elevation). However, if the area of the
enlargement(addition) complies with applicable regulations, the existing portion of the structure
does not have to be elevated.
Reconstruction(repair of damaged structures)is constituted by the rebuilding of an existing
structure which has been partially or completely destroyed by any cause (fire, wind, flood, etc...),
without increasing the floor area of the structure. If a partially destroyed structure is
reconstructed and the cost of the reconstruction equals or exceeds 50% of the market value of the
structure before the damage, then the rebuilt structure is considered substantially improved and is
subject to applicable floodplain regulations. The cost of repair includes all damages sustained
and does not reflect a level of repairs,even if the actual cost of repairs is reduced below the 50%
threshold.
Rehabilitation includes any improvements and repairs which are made to the interior and
exterior of an existing structure,but which do not result in any increase in the floor area of the
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structure. Any rehabilitation of an existing structure, the cost of which equals or exceeds 50%of
the market value of the structure, is subject to the same floodplain management requirements as
new construction.
It must be recognized that there are cases where the three above mentioned types of
improvements are combinations thereof. In the case where two types of alterations are combined
to constitute a substantial improvement, the more restrictive category should be used to apply
floodplain management provisions.
Second story additions are interpreted as a rehabilitation since it would normally involve
tearing off the existing roof. If the cost of constructing the second story, including removal of the
roof, is equal to or greater than 50% of the market value of the existing structure before the
alteration,the entire structure must comply with floodplain regulations (i.e., elevation).
Costs to be included for the calculation of substantial improvement/damage means all structural
costs, as well as all finish materials, built-in appliances,hardware, in addition to profit and
overhead. This includes lighting fixtures, built-in appliances, interior moldings, paneling,tiling,
wall-to-wall carpet over subflooring, built-in cabinets, etc.
Accessory Structures such as a detached garage or shed, need not be elevated or floodproofed
above the base flood elevation as long as the structure is used solely for parking or storage of
equipment used in connection with the dwelling. A newly placed detached garage or shed:
• cannot be used for human habitation
• must have low flood damage potential
• must have minimal resistance to flood flows
• must be adequately anchored
• must have utilities elevated above the base flood elevation
• cannot violate floodway encroachment standards
• must be situated to least block flood flow
• must be built using unfinished and flood resistant materials
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