HomeMy WebLinkAboutCOUNCIL - AGENDA ITEM - 04/06/2004 - FIRST READING OF ORDINANCE NO. 057, 2004, AMENDINGAGENDA ITEM SUMMARY
FORT COLLINS CITY COUNCIL
ITEM NUMBER: 16
DATE: April 6, 2004
STAFF: Jim Hibbard
Bob Smith
SUBJECT
First Reading of Ordinance No. 057, 2004, Amending Chapter 26 of the City Code to Reflect the
Adoption of Updated Master Drainage Plans And to Revise the Official Repository of Plan
Documents.
RECOMMENDATION
Staff recommends adoption of the Ordinance on First Reading. The Water Board, Natural
Resources Advisory Board and the Planning and Zoning Board recommend adoption of the
Ordinance.
FINANCIAL IMPACT
Staff believes the recommended $132 million in City funded flood control projects is achievable
under the current funding plan in approximately 25 years. This funding plan calls for 6 percent
increases in rates for each of the next four years, then level for the next twenty years. City Council
sets stormwater rates as a part of the budget process, which in turn determines the length of time
required to build out the master plans.
EXECUTIVE SUMMARY
The Ordinance updates current City Code references to the master drainage plans for the various
basins in the city by repealing and reenacting Code Section 26-543(a). A number of the master
drainage plans have been updated or revised since the related Code language was modified. This
is in part due to the fact that in 1999, the City Council adopted a higher rainfall standard based upon
a technical analysis of rainfall statistics, which resulted in modifications to the master plans. In
addition, updated topographic information, changes in conditions, and better technical data and
methods has resulted in other improvements from the previously listed plans. Staff has prepared a
Stormwater Master Plan Executive Summary Report that summarizes citywide information and
presents brief summaries of the master plan for each basin. The summarized basin master plans
strive to design projects that provide cost-effective flood protection for a 100-year rainfall event.
The basin master plans recommend a number of flood control and other types of improvements.
In addition, the Ordinance modifies City Code Section 26-543(b), so as to provide that the master
drainage plans and updates to those plans will be maintained on file in the office of the Utilities,
April 6, 2004 -2- Item No. 16
rather than the office of the City Clerk. This change is to improve the efficiency and effectiveness
of the use and maintenance of those records.
BACKGROUND
The Master Plan Executive Summary takes a detailed look at the flooding and water quality
problems in each basin and provides the general direction for stormwater management in those
basins. The stormwater basin master plans include:
1. Recommended projects to reduce flood damage to homes and businesses, the
potential for loss of life, as well as reduce flooding of roads,
2. guidance for new development in the basin,
3. guidance for enhancements to the riparian habitat along stream corridors to improve
water quality, and
4. guidance for stabilizing streams where necessary.
The stormwater master plans strive to design projects that provide cost-effective flood protection
for a 100-year rainfall event.
The Master Plan Executive summary outlines plan-recommended projects to solve existing flooding
problems on both structures and infrastructure. In some cases, projects do reduce the floodplain
on undeveloped land inadvertently. This usually occurs when the problem is downstream of
undeveloped land and the solution is upstream. Since water on undeveloped land does not constitute
a public problem, reduction of the floodplain on undeveloped land is not a goal of the master plan.
New development in a floodplain is required to adhere to the floodplain regulations.
In 1999, Council adopted a higher rainfall standard based upon a technical analysis of rainfall
statistics. Higher rainfall resulted in higher runoff and larger floodplains. This required an update
to all master plans to reflect the higher rainfall and reevaluate the needed capital improvements.
In 2001, Council adopted a revised Canal Importation Basin Master Plan.
In 2001, Council approved a plan to fund $120 million in stormwater improvements over the next
25 years on a pay-as-you-go basis. Monthly fees for a typical residential customer in 2004 are
$14.26. By 2008, monthly fees for the typical residential customer will be $18.35. Monthly fees
will return to maintenance levels in approximately 25 years. New development pays a storm
drainage impact fee. Revision to the impact fee will be brought to Council after adoption of the new
master plan.
Colorado and Federal laws require the city to regulate to the 100-year storm event. This means the
100-year storm is used to map the regulatory floodplain and enforce floodplain regulations. The
City, through Storm Drainage Design Criteria and Construction Standards, also requires developers
to use the 100-year storm for the design of new drainage facilities. Current City policy is master
plans should recommend improvements that provide 100-year protection when the benefits of
projects outweigh their costs. In 2001 Council requested staff to include in future master planning
efforts an analysis of providing flood protection for events less severe than the 100-year flood event.
April 6, 2004 -3- Item No. 16
Existing Conditions Damage Statistics
All basins have been analyzed based on the higher rainfall, resulting in higher runoff flows, and
deeper and wider floodplains. The studies show significant flooding problems in a variety of
locations around the city with the following results:
1. damage could occur to more than 2,600 structures during a 100-year storm,
2. the estimated damage from a single 100-year storm would be approximately $142 million,
and
3. if nothing is done to the existing drainage system, flood damages over the next 50-years are
estimated to be over $353 million.
The 2003 Stormwater Master Plan Executive Summary
In general, the recommended projects include construction or enlargement of detention ponds,
construction of open channels and storm sewers, and enlargement of road culverts. Because master
plans are conceptual in nature, the projects proposed may change based upon actual field conditions
at the time of final design. The attached Stormwater Master Plan Executive Summary Report
(September 2003) provides an overview of the technical process and recommendations of the master
plans from all basins. The first several pages contain a summary of citywide information. This is
followed by one or two page summaries of each basin. The basin master plans strive to design
projects that provide cost-effective flood protection for a 100-year rainfall event. The master plans
recommend:
1. $164 million in flood control projects, $132 million in the City and $32 million funded by
the County and others,
2. $42 million in projects funded by partners (development, grants, etc.) as opportunities arise
for water quality enhancements, and localized drainage improvements,
3. standardized development criteria to reduce peak flow leaving newly developed sites to 2-
years historic or equivalent (many basins already had this requirement),
4. regional water quality treatment opportunities to improve the quality of stormwater runoff
and,
5. expanded wetlands and improved riparian habitat opportunities along natural channels to
improve the quality of stormwater runoff.
Overall, the basin master plans reduce or eliminate the majority of structural damages caused by
flooding in the city. Staff estimates flood damage will be eliminated on approximately 2,200
structures, almost 85% of the total number of damaged structures. The following table summarizes
the benefits of the recommended master plans.
April 6, 2004 -4- Item No. 16
Benefit of $164 Million in Flood Control Projects
Before After
Property Damage Over the
Next 50-Years $353 million $63 million
Number of Structures
Damaged by 100-Year Storm 2,600 400
In addition to the above tangible benefits of reduced damages to structures, the following intangible
benefits are not included in the estimates:
1. reduced damages to vehicles and public infrastructure,
2. reduced emergency response, evacuation, clean-up, temporary housing costs,
3. streets are open during flooding events for emergency response vehicles,
4. improved water quality, environmental enhancement, and providing a feeling of safety and
security for citizens, and
5. reduced risk of injury and/or loss of life.
To the extent possible, the proposed flood control projects provide opportunities to enhance and
expand wetlands and natural habitat areas to improve the quality of storm runoff. Recommendations
to retain and improve existing riparian habitat along the natural channels are also included.
Staff believes the completion of $132 million in City funded flood control projects is achievable
under the approved funding plan in approximately 25 years.
The proposed Boxelder/Cooper Slough Master Plan currently recommends improvements in
Boxelder/Cooper Slough basin to solve flood damage problems in the Mulberry/I-25 area.
However, this basin does have a large amount of undeveloped land in the floodplain as well as a
large amount of land in the Mountain Vista Subarea that does not have an adequate drainage outfall.
Additional study by both the City and the County has begun in order to determine development
guidance and identify possible solutions to stormwater issues in these areas. Staff will return to
Council with the results of this additional study if necessary.
Reduced Level of Protection Analysis
The recommended plan of improvements is based upon providing a 100-year level of flood
protection whenever it is cost effective. In 2001, Council asked staff to look at the costs and benefits
of providing a reduced level of protection in future master planning efforts. Staff looked at a 50-
year level of protection for this analysis. Under this scenario, the regulatory floodplain is still
mapped using the 100-year storm and property and structures remaining in the floodplain after
projects are built are subject to flood damages and floodplain regulations.
April 6, 2004 -5- Item No. 16
The following table shows the costs and benefits of the 50-year level of protection plan and provides
a comparison with the recommended 100-year level-of-protection plan.
Reduced Level of Protection Analysis
100-Year Level of
Protection
50-Year Level of
Protection
Cost of Flood Control
Projects $ 164 million $ 141 million
Property Damage
Reduced $ 290 million $ 146 million
Number of Structures -
Damages Eliminated 2,200 1,500
Although the cost of the 100-year plan is high, the favorable benefit to cost ratio shows the
effectiveness of the plan. Compared to the lower level of protection plan, an additional $20 million
in projects will result in $144 million in damage reduction on 700 structures. This extra investment
also represents a significant reduction in risk to the citizens.
At the January 13, 2004 Study Session, City Council supported the 100-year level of protection.
Public Outreach
The process of informing property owners in the City’s 12 stormwater basins of upcoming changes
to both the master plans and floodplain regulations began in early 2002 and continued until late
2003. A variety of communication tools such as customer mailings, web pages, press releases and
media interviews, public meetings and open houses, and outreach to both internal and external
groups potentially affected were used.
In 2002, customers most affected by floodplain boundaries and proposed regulations were identified
as the primary focus of initial outreach. Because a significant number of those within the mapped
floodplains are Larimer County residents, City and County staff collaborated on public outreach.
Eight public open houses were held to provide an opportunity for customers and staff to discuss the
information included in the mailings as well as the master planning process. Customers received
mailed invitations and open houses were advertised in the Fort Collins Coloradoan and North Forty
News. At the same time, web pages were developed on the Utilities Web site to provide additional
information. Over 4,000 packets were mailed, and 250 people attended the 8 open houses held
during the year.
In 2003, public outreach was expanded to include all property owners and renters in the City’s
stormwater drainage basins, not just those within the mapped floodplains. At a kickoff open house
held in February, property owners and renters were invited to learn more about the City’s
stormwater drainage basins, floodplains and regulations, safety and flood protections, and the
regional weather patterns that can result in flash flooding.
April 6, 2004 -6- Item No. 16
Following the kickoff, nine additional public open houses were held. Information presented at the
open houses consisted of basin-specific information as well as information about the citywide
planning process, including:
1. flooding histories for each basin,
2. maps showing identified basin problems,
3. maps showing proposed solutions,
4. proposed floodplain regulations,
5. stormwater project funding, and
6. the process for adoption of master planning and floodplain regulations.
Over 62,000 pieces of mail were sent, including informational packets, basin-wide kickoff
invitations, open house invitations and letters to 24 community organizations. Publicity for the
outreach campaign included media releases and briefings, and advertising in local media.
The nine open houses were attended by 470 people. Of the 24 community organizations contacted,
seven asked for presentations or more information. Presentations were made to six City Boards,
including the Water Board, the Natural Resources Advisory Board, the Planning and Zoning Board,
the Affordable Housing Board, Landmark Preservation Board and Parks and Recreation Board.
Comment forms were available at the open houses and on the Utilities Web site. Thirty-three
comment forms were submitted. Although most of those who attended open houses did not
comment formally on either the proposed master plans or floodplain regulations, almost everyone
got a chance to express their views to staff.
Comments received on master plan issues can generally be summarized as follows:
1. support for specific projects, build as soon as possible,
2. support for master planning as a whole, it seems reasonable,
3. questions about local drainage issues,
4. make sure water quality is an integral part of capital projects,
5. concern projects don’t encourage mosquitoes,
6. support for the 100-year level of protection,
7. do more to protect citizens,
8. implementation of the master plans is too expensive, flooding is rare,
9. balance habitat protection with recreational users,
10. keep streams natural, not structural,
11. questions about impact of recent nearby development,
12. concern that projects remove vacant land from the floodplain, which allows development,
and
13. would like to see funding changed back to basin by basin, floodplain properties should pay
more.
In March of 2004, about 10,000 post cards were mailed to customers who live or have property in
floodplains, informing them that the updated basin master plans would be considered by City
Council on April 6.
April 6, 2004 -7- Item No. 16
ATTACHMENTS
Stormwater Master Plan Executive Summary Report
Stormwater Master Plan Summary Table
Flooding History in Fort Collins
Recommendation from Water Board
Recommendation from Natural Resources Board
Recommendation from Planning and Zoning Board
January 13, 2004 Study Session Summary
ORDINANCE NO. 057, 2004
OF THE COUNCIL OF THE CITY OF FORT COLLINS
AMENDING CHAPTER 26 OF THE CITY CODE TO
REFLECT THE ADOPTION OF UPDATED MASTER DRAINAGE PLANS
AND TO REVISE THE OFFICIAL REPOSITORY OF PLAN DOCUMENTS
WHEREAS, Section 26-543 of the Code of the City of Fort Collins adopted by reference
and declared a part of the City Code a master drainage plan for each of eleven areas of the city,
for use as the basis for City storm drainage capital improvements planning and determinations
related to storm drainage impacts and requirements for developments in the city; and
WHEREAS, City staff has developed updated master drainage plans analyzing storm
drainage in the various basins of the city (the “Updated Plans”), which Updated Plans are on file
and available for public inspection at Utilities; and
WHEREAS, staff has summarized and outlined the conclusions of each of the Updated
Plans in a “Stormwater Master Plan Executive Summary Report”, dated September 2003 (the
“Executive Summary”), which is on file in the office of the City Clerk and available for public
inspection; and
WHEREAS, the Updated Plans and Executive Summary have been reviewed by the
City=s Water Board, Parks and Recreation Board, Affordable Housing Board, Landmark
Preservation Commission, Natural Resources Advisory Board, and Planning and Zoning Board,
and comments received from these boards have been addressed in the final preparation of the
Updated Plans and Executive Summary; and
WHEREAS, the City’s Water Board, the Planning and Zoning Board and the Natural
Resources Advisory Board took formal action and unanimously passed individual motions
recommending adoption by City Council; and
WHEREAS, staff presented the Updated Plans and the Executive Summary to the City
Council for Council review at its Study Session of January 13, 2004, and at that time received
direction to present the same to the Council for approval; and
WHEREAS, the modification of City Code Section 26-543(a) so as to provide a current
reference to the Updated Plans instead of the previously approved plans will assist the public in
identifying the applicable storm drainage plans and requirements applicable in particular
locations throughout the city; and
WHEREAS, for the foregoing reasons, the City Council wishes to amend the City Code
in order to reflect the approval of the aforementioned Updated Plans, as generally described and
summarized in the Executive Summary; and
WHEREAS, City Code Section 26-543(b) currently requires that master drainage plans
be on file with the office of the City Clerk, but those records can be maintained more efficiently
and effectively by Utility Services, given Utilities’ role in reviewing and implementing the
plans; and
WHEREAS, in order to allow the master drainage plans and updates thereto to be
maintained on file at Utilities, a modification of said Code language is necessary.
NOW, THEREFORE, BE IT ORDAINED BY THE COUNCIL OF THE CITY OF
FORT COLLINS as follows:
Section 1. That Chapter 26 of the Code of the City of Fort Collins is hereby repeal
and reenact Section 26-543(a), to read as follows:
Sec. 26-543. Master drainage plans.
(a) Master drainage plans are hereby adopted by reference and declared to be
a part of this Article for the following stormwater basins of the city:
(1) McClellands Creek Master Drainage Plan Update, prepared by ICON
Engineering, Inc., dated November 2000 and revised March 2003;
(2) East Harmony Portion of McClellands Creek Master Drainage Plan
Update, prepared by ICON Engineering, Inc., dated August 1999 and
revised July 2001;
(3) Foothills Basin, prepared by URS Corporation, Inc., dated April 2003;
(4) Dry Creek Master Plan, prepared by URS Corporation, Inc., dated
December 2002;
(5) West Vine Master Plan, prepared by URS Corporation, Inc., dated
November 2002;
(6) Spring Creek Basin Master Drainage Plan, prepared by Anderson
Consulting Engineers, Inc., dated June 2003;
(7) Fossil Creek Drainage Basin Master Drainageway Planning Restudy,
prepared by ICON Engineering, Inc., dated February 2003;
(8) Old Town Basin Master Drainage Plan, prepared by Anderson
Engineering Consultants, Inc., dated September 2003;
(9) Fox Meadows Basin Drainage Master Plan Update, prepared by ICON
Engineering, Inc., dated December 2002 and revised February 2003;
(10) Mail Creek Master Plan, prepared by URS Corporation, Inc., dated April
2003;
(11) Cache la Poudre River Master Drainageway Plan, prepared by Ayres
Associates, Inc., dated August 2001;
(12) Boxelder/Cooper Slough Basin, prepared by Anderson Consulting
Engineers, Inc., dated December 2002 and revised November 2003; and
(13) Canal Importation Master Drainage Plan, prepared by Anderson
Consulting Engineers, dated April 2001.
Section 2. That City Code Section 26-543(b) is hereby amended to read as
follows:
(b) The General Manager shall maintain the above master drainage plans are
on file in the office of the City ClerkUtilities. The city General Manager may
adopt additional master drainage plans by reference and declare them to be a part
of this Article and copies of such master drainage plans shall be on file in the
office of the City ClerkUtilities. TheAny such plans may be modified by the
General Manager, for the sole purpose of enhancing such plan, provided that such
enhancement does not diminish the general purpose and specific objectives of the
adopted plan and does not diminish the ability of the plan to address the
disposition of stormwater runoff in the applicable basin, and if modified, the
modification shall be filed in the office of the City ClerkUtility Services.
Introduced and considered favorably on first reading and ordered published this 6th day of
April, A.D. 2004, and to be presented for final passage on the 20th day of April, A.D. 2004.
_________________________________
Mayor
ATTEST:
_____________________________
City Clerk
Passed and adopted on final reading this 20th day of April, A.D. 2004.
_________________________________
Mayor
ATTEST:
_____________________________
City Clerk
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Stormwater Master Plan Executive summary
Stormwater Master Plan
Executive Summary Report
September 2003
City of Fort Collins Utilities, PO Box 580, Fort Collins, CO 80522 • (970) 221-6700 • www.fcgov.com/stormwater
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City of Fort Collins Utilities
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This Executive Summary has been prepared by City of Fort Collins Utilities staff utilizing the technical information from
the following basin master plans.
Basin Name Prepared by
• Boxelder/Cooper Slough Anderson Consulting Engineers, Inc.
• Canal Importation Anderson Consulting Engineers, Inc.
• Dry Creek URS Corporation
• Foothills URS Corporation
• Fossil Creek ICON Engineering, Inc.
• Fox Meadows ICON Engineering, Inc.
• Mail Creek URS Corporation
• McClellands Creek ICON Engineering, Inc.
• Old Town Anderson Consulting Engineers, Inc.
• Poudre River Ayres Associates
• Spring Creek Anderson Consulting Engineers, Inc.
• West Vine URS Corporation
Acknowledgments
ii
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Stormwater Master Plan Executive summary
Table of contents
Acknowledgments ii
Summary Report 4
Stormwater Drainage Basins and Map 6–7
Citywide Problem and Solution Maps 8–11
Individual Basin Information
• Boxelder Creek and Cooper Slough 12
• Canal Importation 14
• Dry Creek 16
• Fossil Creek 18
• Foothills 20
• Fox Meadows 21
• Mail Creek 22
• McClellands 23
• Old Town 24
• Poudre River 26
• Spring Creek 28
• West Vine 30
iii
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City of Fort Collins Utilities
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Master planning enables the City of Fort Collins Utilities to
identify stormwater management issues and create solutions
to potential fl ood risks. Master plans provide:
• Proposed projects to reduce fl ood damage to homes
and businesses;
• Proposed projects to reduce fl ooding of roads;
• Guidance for new development;
• Guidance for enhancements to the riparian habitat
along stream corridors;
• Improvements to water quality; and
• Guidance for stabilizing streams where necessary.
Master plans are conceptual and serve to provide the
general direction for stormwater management within the
basin. Some of the factors considered in development of
master plans include:
• Flood control,
• Cost effectiveness,
• Development criteria
• Water quality,
• Riparian habitat and
• Stream stability.
Strategies for reducing fl ood damage typically include
detention facilities, storm sewers, culverts, open channels
and stream improvements. Enhancement of habitat and
environmental corridors are an important consideration
in planning for these projects. In some basins, excessive
erosion and unstable, steep banks compromise water
quality and habitat. When appropriate, proposed
solutions include improvements that incorporate water
quality, enhancements or expansion to wetland areas, as
well as stream habitat and riparian vegetation.
Projects and solutions to fl ood damage within a basin
are developed by evaluating a number of approaches
and alternative strategies. Each approach is evaluated for
effective strategies to decrease fl ood risk and damages.
The basic approaches to fi nding solutions to fl ood
damages include:
• Do nothing – includes enforcing our existing
fl oodplain regulations, development criteria and
utilizing our fl oodwarning system, but does not include
projects to reduce fl ood damages. The goal is to keep
damages at current levels;
• Purchase properties in the fl oodplain – reduces the
damages by removing structures in the fl oodplain, but
does not change the fl oodplain;
• Evacuate the water faster – includes building bigger
channels and pipes to drain water faster and reduce the
fl oodplain, thereby reducing fl ood damages;
• Slow the water down – uses detention ponds to control
water and slow it down to fi t into the channels and
pipes downstream, thereby reducing fl ood damages; or
• A combination of any or all of the above.
Prior to the 1960s, drainage facilities, such as storm sewers
and street gutters, often were designed to accommodate
minor storms that might occur every few years.
Consequently, during major storms, neighborhoods and
commercial areas in the oldest sections of Fort Collins
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Stormwater Master Plan Executive summary
New Rainfall Standards
Following the devastating fl ood of 1997 , the City of Fort
Collins embarked on a study to re-evaluate the amount
of rainfall associated with the 100-year frequency storm.
A Precipitation Study Task Force, with members from
regulatory agencies, technical fi elds and private citizens,
provided the guidance for the study.
In 1999, City Council adopted the new rainfall standards
to be used in the design of stormwater facilities in the city.
The old standard of 2.89 inches over a two-hour period
was revised to 3.67 inches for the 100-year design storm.
Because of the new 100-year standard, standards for the more
frequent storms and the 500-year storm were revised as well.
Development Guidance
Together with fl oodplain regulations, the master plans also
provide guidance for new development in order to prevent
additional fl ood problems.
In the future, the City of Fort Collins Storm Drainage
Design Criteria and Construction Standards will guide
design and implementation of all stormwater conveyance
facilities. In general, new development will be required to
have on-site detention to reduce the peak fl ow leaving the
site. These detention ponds will typically provide a water
quality component in order to treat some of the runoff before
it leaves the site.
In addition, adherence to erosion buffer limits, developed
along many of the natural streams, is recommended for all
An extensive public outreach program which
included basin-specifi c open houses and
individual mailings, began in 2002 to inform
citizens and gather public comment.
new development. These buffer limits help minimize the
potential damage associated with active channel erosion and
encroachment of future development.
Citywide Problems and Solutions
Studies indicate that signifi cant problems are found in a
variety of locations around the city. The citywide problems
and solution maps provide a summary of the problems
and recommended solutions (pages 7–10). The following
statistics are based on the conclusions of the Technical
Drainage Master Plan Reports:
• More than 2,600 structures could be damaged during
a 100-year storm;
• The estimated damage from a 100-year storm,
if no improvements are made, is approximately
$141.6 million;
• If nothing is done to reduce damages over the next
50 years, fl ood damages are estimated to be over
$353 million;
• The estimated total cost for all proposed stormwater
management improvements is approximately
$210 million (proposed projects which reduce damages
to homes and businesses is $164 million);
• The estimated amount of damage reduction from
these proposed improvements is approximately
$290 million; and
• Damages would be eliminated on approximately
2,200 structures, almost 85% of the total number
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City of Fort Collins Utilities
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Each basin has unique characteristics, including physical
topography, land uses (both existing uses and potential for
future development) and the presence of drainage channels
and drainage pathways. These characteristics are evaluated
in the technical studies conducted for each basin. Basin
Stormwater Drainage Basins
The Fort Collins area is divided into 11 stormwater drainage basins, featured on the map on the following page.
Basin Size (sq. miles) Land Uses
• Boxelder Creek/Cooper Slough 265 mostly farmland
• Dry Creek 62 farmland, developed in southern sections
• Old Town 3.3 highly urbanized
• West Vine 3.7 urban and rural
• Canal Importation 5 highly urbanized
• Spring Creek 99 urban and open space/parks
• Foothills 5 mostly urban
• Fox Meadows 2.4 majority urban
• McClellands / Mail Creek 5.9 farmland, and urban growth
• Fossil Creek 32 urban and rural
• Poudre River 1,890 mountains, rural and urban
studies involve basin inspections, hydrology (amount
of fl ow) and hydraulic analyses (fl ow paths), problem
identifi cation, alternatives analysis and a recommended
plan for improvements.
Mountain Avenue, above, is an area where the street
becomes the stream channel. At right is a natural stream
in a rural area.
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Stormwater Master Plan Executive summary
Fort Collins Stormwater Drainage Basins
LEGEND
CANAL IMPORTATION BASIN
BOXELDER/COOPER SLOUGH BASIN
DRY CREEK BASIN
FOOTHILLS BASIN
FOSSIL CREEK BASIN
FOX MEADOWS BASIN
MCCLELLANDS/MAIL CREEK BASIN
OLD TOWN BASIN
SPRING CREEK BASIN
WEST VINE BASIN
WATER FEATURES
E DOUGLAS RD
E VINE DR
LAPORTE AVE
MULBERRY ST
PROSPECT RD
DRAKE RD
HORSETOOTH RD
HARMONY RD
TRILBY RD
S CNTY RD 5
TAFT HILL RD
SHIELDS ST
COLLEGE AVE
LEMAY AVE
TIMBERLINE RD
S CNTY RD 19
S CNTY LINE RD
W CNTY RD 38E
OVERLAND TRL
I-25
ZIEGLER RD
E CNTY RD 30
POUDRE RIVER BASIN
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City of Fort Collins Utilities
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Citywide Problem Map - North
E VINE DR
INTERSTATE 25
E PROSPECT RD
LAPORTE AVE
N TAFT HILL RD
N SHIELDS ST
W VINE DR
E MULBERRY ST
W MULBERRY ST
W PROSPECT RD
E COUNTY ROAD 52
S LEMAY AVE
S SHIELDS ST
S TAFT HILL RD
E LINCOLN AVE
RIVERSIDE AVE
N COLLEGE AVE
S COLLEGE AVE
S TIMBERLINE RD
S OVERLAND TRL
N OVERLAND TRL
N LEMAY AVE
N US HIGHWAY 287
N COUNTY ROAD 9
COUNTY ROAD 54G
TERRY LAKE RD
N COUNTY ROAD 11
COUNTRY CLUB RD
N TIMBERLINE RD
E WILLOX LN
GREGORY RD
W WILLOX LN
S SUMMIT VIEW DR
9TH ST
E COUNTY ROAD 50
JEFFERSON ST
INTERSTATE 25
N OVERLAND TRL
Lake Canal
New Mercer Canal
Spring Creek
Boxelder Creek
Terry Lake
Long Pond
Arthur Canal
Cache La Poudre Res. Inlet
Sherwood Lateral
Lindenmeier Lake
Richard’s Lake
Lee Lake
Boxelder Creek
Legend
High Risk Floodplain
Moderate Risk Floodplain
Depth of Overtopping
0−1
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Stormwater Master Plan Executive summary
Citywide Solutions Map - North
E VINE DR
INTERSTATE 25
LAPORTE AVE
E PROSPECT RD
E DRAKE RD
W DRAKE RD
S LEMAY AVE
S SHIELDS ST
S TAFT HILL RD
W VINE DR
W MULBERRY ST
W PROSPECT RD
S COLLEGE AVE
S TIMBERLINE RD
S OVERLAND TRL
N SHIELDS ST
E MULBERRY ST
E LINCOLN AVE
RIVERSIDE AVE
N COLLEGE AVE
N TAFT HILL RD
N LEMAY AVE
N OVERLAND TRL
N TIMBERLINE RD
E WILLOX LN
W WILLOX LN
MOUNTAIN VISTA DR
S SUMMIT VIEW DR
9TH ST
COUNTY ROAD 42C
S COUNTY ROAD 23
JEFFERSON ST
E COUNTY ROAD 50
INTERSTATE 25
Lake Canal
Cache La Poudre River
New Mercer Canal
Spring Creek
Boxelder Creek
Arthur Canal
Sherwood Lateral
Dixon Creek
New Mercer Ditch
Foothills Channel
Lindenmeier Lake
Lee Lake
Spring Creek
Legend
Embankments
Culverts
Pipes
Channels
Ponds
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City of Fort Collins Utilities
10
Citywide Problem Map - South
S SHIELDS ST
INTERSTATE 25
S COLLEGE AVE
S TAFT HILL RD
S TIMBERLINE RD
E DRAKE RD
W DRAKE RD
E HORSETOOTH RD
E TRILBY RD
S LEMAY AVE
W TRILBY RD
E HARMONY RD
W HARMONY RD
W HORSETOOTH RD
E COUNTY ROAD 32
CARPENTER RD
KECHTER RD
ZIEGLER RD
W COUNTY ROAD 38E
STRAUSS CABIN RD
S COUNTY ROAD 19
S COUNTY ROAD 7
S CENTENNIAL DR
S COUNTY ROAD 9
E COUNTY ROAD 36
INTERSTATE 25
ZIEGLER RD
S LEMAY AVE
E COUNTY ROAD 32
S LEMAY AVE
Mail Creek Ditch
Fossil Creek
Boxelder Ditch
New Mercer Ditch
McClellands Channel
Spring Creek
Larimer County Canal No. 2
Foothills Channel
Dixon Creek
Warren Lake
Dixon Reservoir
Duck Lake
Lake Sherwood
Fossil Creek
Fossil Creek
Legend
High Risk Floodplain
Moderate Risk Floodplain
Depth of Overtopping
0−1
1−2
2+
11
Stormwater Master Plan Executive summary
Citywide Solutions Map - South
S SHIELDS ST
INTERSTATE 25
S COLLEGE AVE
S TAFT HILL RD
E HARMONY RD
S TIMBERLINE RD
E HORSETOOTH RD
E TRILBY RD
S LEMAY AVE
W TRILBY RD
W HARMONY RD
W HORSETOOTH RD
E COUNTY ROAD 32
CARPENTER RD
KECHTER RD
ZIEGLER RD
STRAUSS CABIN RD
W COUNTY ROAD 38E
S COUNTY ROAD 19
S COUNTY ROAD 7
E COUNTY ROAD 36
S COUNTY ROAD 9
S CENTENNIAL DR
S COUNTY ROAD 11
E COUNTY ROAD 32
ZIEGLER RD
INTERSTATE 25
S LEMAY AVE
S LEMAY AVE
Mail Creek Ditch
Fossil Creek
Boxelder Ditch
McClellands Channel
Fossil Creek Reservoir Inlet
Dixon Canyon Lateral
Spring Creek
New Mercer Ditch
Foothills Channel
Warren Lake
Duck Lake
Fossil Creek
Fossil Creek
Legend
Embankments
Culverts
Pipes
Channels
Ponds
12
City of Fort Collins Utilities
12
Boxelder Creek and
Cooper Slough
About the Basins
The Boxelder Creek and Cooper Slough Basins
encompass approximately 265 square miles beginning at
the Colorado/Wyoming border, extending southward into
east Fort Collins and ending at the Cache la Poudre River.
The basins are primarily characterized by farmland with
isolated areas of mixed-use residential development and
limited commercial development.
These basins are interconnected. Floodwaters from
Boxelder Creek Basin can spill into Cooper Slough Basin
upstream of Vine Drive. Most of the water from Cooper
Slough drains into Boxelder Creek at Prospect Road, near
the downstream end of the basins.
Larimer County and the City of Fort Collins prepared
the original fl oodplain study in 1981. In the later part of
2002, Fort Collins Utilities, in cooperation with Larimer
County, revised the fl oodplain map for the basins as
part of a comprehensive update of the City’s stormwater
master plans.
Storm runoff from the upper 186 square miles of the
basin is controlled by a series of fl ood control reservoirs.
However, the lower 80 square miles of the basin can
generate a substantial amount of runoff contributing to
fl ooding along Boxelder Creek and Cooper Slough on both
sides of I-25. A portion of this runoff crosses I-25 through
the Larimer and Weld Canal and also contributes to
fl ooding problems on the west side of the interstate.
Flooding History
Major fl oods occurred in these basins in 1909, 1922, 1930,
1937, 1947, 1963, 1967 and 1969. In 1947, a Coloradoan
newspaper headline read, “Violent Rainstorm Floods Large
Area; Crop Losses Heavy.” As much as fi ve inches of rain
fell northwest of Wellington, washing out bridges and
fl ooding crops. Nearly 1,000 acres of grain, alfalfa and corn
crops were damaged. Heavy rains caused Boxelder Creek to
overfl ow its banks again in 1967 and resulted in the death
of a mother and her three daughters who drove into the
fl ooded creek where it passed over a county road southeast
of Wellington. Floods that summer destroyed county
bridges seven times.
In a rural area of Boxelder Creek, concrete rubble is used to
stabilize the bank from further erosion.
13
Stormwater Master Plan Executive summary
Basin Problems
The master plan update estimated that 134 structures
would be damaged during a 100-year storm with the most
signifi cant structural damage at the State Highway 14 and
I-25 intersection. There are also 18 roads within the basin
that would be overtopped during a 100-year storm. The
master plan estimated that there would be $23 million in
damages during a 100-year storm. If nothing is done to
mitigate this damage, it is estimated that $62 million of
damage would occur over the next 50 years.
In addition to fl ooding hazards, erosion has occurred
because of natural processes, agricultural practices and
urban development. Excessive erosion leads to poor water
quality, damage to adjacent property, roads and utilities and
reduced biological diversity to support riparian habitat.
Recommended Solutions
The recommended selected plan of improvements
was developed to provide cost-effective solutions to
mitigate damages from the 100-year storm. Most of the
recommended improvements are located at the northwest
and southwest corners of Highway 14 and I-25, where the
majority of the existing damage to structures is anticipated.
The improvements include:
• Box culvert in the business park north of Highway 14;
• Box culvert under Highway 14 for Cooper Slough;
• Channelization of Cooper Slough and Lake Canal south of
Highway 14 to Boxelder Creek; and
• Box culvert under Prospect Road at Boxelder Creek.
These projects would prevent 91 structures from being
damaged and eliminate two roads from overtopping in a 100-
year storm. The total cost is $19.2 million and the benefi t-to-
cost ratio is 3.26. Approximately 43 structures would still be
damaged in the 100-year storm.
Stream Stability and Habitat
The master plan also recommends opportunities to enhance
the riparian habitat and address erosion along Boxelder
Creek. This includes constructing sloping boulder drop
structures, sloping back vertical banks and re-establishing
native landscaping to promote biological diversity along the
stream. The goal is to preserve areas with good habitat and
enhance areas of poor habitat.
New Development Guidance
Another important aspect of the master plan is to provide
guidance for new development. The plan recommends that
two corridors in the basin be further studied to address
needed drainage infrastructure. The fi rst corridor is east
of I-25 in the Boxelder Creek Basin. The second corridor
is located north of the Larimer and Weld Canal within the
Cooper Slough Basin, known as the Mountain Vista subarea.
Regional Opportunities
The Boxelder Creek fl oodplain also impacts the towns
of Wellington and Timnath, as well as a large amount of
sparsely developed and undeveloped property east of I-25.
The County and the City, along with the other affected
communities and landowners, will persue a regional master
plan for the basin. This plan could reduce the size of the
fl oodplain by constructing additional fl ood detention in
the basin or channeling the Boxelder Creek overfl ow path
14
City of Fort Collins Utilities
14
Canal Importation
About the Basin
The Canal Importation Drainage Basin spans nearly fi ve
square miles in west-central Fort Collins. Three major
irrigation canals traverse the basin from north to south and
impact drainage in the basin. The canals can intercept runoff
traveling through the basin and transport it out of the basin,
and they also spill runoff into the basin when their capacity
is exceeded.
The basin, which suffered signifi cant property damage
in the fl ood of 1997, is almost completely urbanized with
primarily mixed density residential and isolated commercial
land uses. Runoff from the basin empties into the Old Town
and Spring Creek Basins.
Much development in the basin occurred before the City
adopted drainage criteria. The basin’s original master plan,
prepared in 1980, identifi ed several drainage improvement
projects. Many of these projects have been completed or are
in the process of being constructed, including the Sheldon
Lake Drainage Improvement Project, Canal Importation
Channel, Fairbrooke Detention Pond, Rodeo Detention
Pond, Willow Lane Channel, Plum Street Regional
Detention Pond and a spill structure and outlet pipe at
Prospect Road. Other improvements include construction
of the Fairbrooke Channel, enlargement of the Avery
Park Detention Pond, widening of Clearview
Channel and construction of Hughes Stadium
Detention Pond.
In 2000, the City of Fort Collins Utilities
mapped a new fl oodplain for this area as part of
a comprehensive update of the basin’s stormwater
master plan.
Flooding History
During storms, water from the west fl ows into the
three irrigation canals until they fi ll up and spill
where the banks are low. Floodwaters travel east
until they reach the Colorado State University
campus and Old Town area. The basin has experienced
fl ooding many times due to its urban nature and because
surrounding development took place in the 1950s, prior to
a stormwater drainage program.
In September 1938, over four and a half inches of rain fell
in 48 hours west of town and caused widespread damage.
The Evening Courier reported, “Although almost all ditches
had to be shut off at the river to keep them from breaking
their banks, drainage kept most of them full.” More
fl ooding occurred in August 1951, when over six inches
of rain fell in 27 hours, with slightly more than one inch
falling in 15 minutes. The Fort Collins Coloradoan reported,
“Mr. Wilkinson said the New Mercer, Larimer County
No. 2 and Arthur Ditches west of Fort Collins did not have
any breaks. However, ‘pick-ups’ from fl ash fl oods caused
all of them to overfl ow, the water fl ooding the Colorado
A&M college campus.”
During the morning of August 13, 1975, the basin received
nearly four inches of rain. The Coloradoan reported, “The
hardest hit section apparently was near Avery Park where
15
Stormwater Master Plan Executive summary
Flooding in July 1997 caused signifi cant damage through-
out the Canal Importation Basin. Water fl ooded homes
and businesses and trapped people in cars. Elizabeth and
Lake Streets became torrents of water rushing toward the
CSU campus. CSU suffered $100 million in damages to
buildings and property in the worst fl ooding ever seen in
the area. A storm in April 1999 also caused some minor
fl ooding damage to homes in the basin.
Basin Problems
Flooding potential in the basin continues to be widespread,
due to signifi cant loss of natural drainage channels and
uncontrolled spilling of storm runoff from the canals.
A 100-year storm event would result in more than 700
structures being fl ooded with total damages estimated at
$25.6 million. If nothing is done to mitigate this damage,
it is estimated that $125 million of direct fl ood damage
would occur over the next 50 years.
During a 100-year storm, there is signifi cant street and
neighborhood fl ooding, severely impeding traffi c and
placing citizens and emergency responders at risk.
• Taft Hill Road would be overtopped at fi ve locations;
• Shields Street, Prospect Road and Overland Trail would
be overtopped at several locations;
• Signifi cant street fl ooding would occur along West
Elizabeth, West Mulberry, Mountain and Oak Streets;
• Many other collector and local streets would be fl ooded
or overtopped; and
• Entire neighborhoods could be fl ooded.
Recommended Solutions
In 2001, Council adopted the Canal Importation Basin
Master Plan. Some projects have been completed or are
underway. The following information represents the
information adopted by Council.
Flood Damage
The recommended plan of improvements was developed
to provide cost-effective solutions to mitigate fl ood damage
from the 100-year storm. The plan includes building
detention ponds where possible to slow the water down,
constructing larger culverts under roads and storm sewers
to drain neighborhoods, building open channels and
modifying some of the irrigation canals to carry more
stormwater runoff.
• Detention Ponds: Sheldon Lake, City Park Nine Golf
Course, West Orchard, Glenmoor, West Prospect,
Fairbrooke, Kane and Red Fox Meadows;
• Road Culverts: Taft Hill Road, Skyline Drive, Hampshire
Road, Langshire Drive, Stuart Street and Hillcrest Drive;
• Storm Sewers: Mulberry Street, Cook Drive, Plum
Channel (south of Orchard Place), Elizabeth Street,
Prospect Road/Overland Trail, Drake Road to
Spring Creek;
• Open Channels: parallel channel to the west of the
Pleasant Valley and Lake Canal from Stuart Street to
Drake Road; and
• Irrigation Canals: Pleasant Valley and Lake Canal from
Prospect Road to Fairbrooke Channel and New Mercer
Ditch from Elizabeth Street to south of Prospect Road.
The total cost is $51.5 million and the benefi t-to-cost ratio
16
City of Fort Collins Utilities
16
Dry Creek
About the Basin
Dry Creek, a tributary to the Poudre River, extends from
near the Wyoming border to where it joins the river near
Mulberry Street and Timberline Road. The Dry Creek
Basin is approximately 23 miles long and six miles wide,
encompassing approximately 62 square miles. The upper
and middle portions of the basin are primarily used as
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This 1950 aerial photo of the lower Dry
Creek Basin shows the prominent channel
from Willox Lane south and east to the
point where Dry Creek joins the Poudre
River. Today, the channel has been severely
altered by development and agriculture
17
Stormwater Master Plan Executive summary
over into Dry Creek and “fl ooded
tourist camps, stores and houses
on the west side of North College
Avenue north of City limits.” In
the same storm, another 20 houses
fl ooded in the Goering Addition,
west of the old speedway track at the
northwest corner of Willox Lane and
College Avenue. In 1977, another
storm brought 4.28 inches of rain in
24 hours, fl ooding basements north
of town, most likely in the Dry
Creek Basin.
In spite of the small number of
reported fl oods in the Dry Creek
Basin, it contains a very large
drainage area and signifi cant
fl ooding could occur at any time.
Basin Problems
While there is no documented history of fl ooding in the
upper and middle portions of the basin, a large storm could
threaten the lower basin. In the lower basin, there are 614
structures, nine roads, Larimer and Weld Canal and one
railroad that would be damaged during a 100-year storm
event, with an estimated $24.4 million in damage. If nothing
is done to mitigate this damage, it is estimated that $21.6
million of damage would occur over the next 50 years.
Minor fl ooding has occurred in the lower portion of the
basin due to inadequate or non-existent drainage facilities.
Areas south of the Larimer and Weld Canal would be
fl ooded if the canal were overtopped during a large storm.
Areas of potential fl ooding include, but are not limited to:
• Airpark business area, including the runway and
several hangars;
• Several mobile home parks and neighborhoods;
• Vine Drive, College Avenue, Lemay Avenue and
Mulberry Street; and
• The intersection of Redwood and Conifer Streets.
Recommended Solutions
Flood Damage
The improvement plan was developed to provide cost-
effective solutions to mitigate fl ood damage from a 100-year
storm. Projects include:
• Dry Creek Flood Control Project: a combination of
projects in the upper, middle and lower basins to reduce
the amount of fl ooding. Projects include modifi cations to
Douglas Reservoir Dam, construction of three detention
ponds, installation of a SCADA system, construction of an
irrigation water supply pipeline from Larimer County Canal
to the Terry Lake Inlet Ditch and construction of open
channels to carry the fl ow to the Poudre River; and
• Lower basin: a combination of projects to help solve local
fl ooding problems. Projects include the Lemay Channel,
Lincoln Channel and College Avenue storm sewer.
The total cost is $25.2 million and the benefi t-to-cost ratio is
1.04. When all improvements are in place, it is estimated that
no structures will be damaged in the 100-year storm.
Excessive Erosion/Poor Stream Habitat
18
City of Fort Collins Utilities
18
Fossil Creek
About the Basin
The Fossil Creek Drainage Basin extends along the south
end of Fort Collins, from the foothills across Interstate 25
past County Road 5. It encompasses 32 square miles in
the city of Fort Collins and Larimer County. Historically,
the basin consisted of agricultural land, but the basin has
experienced signifi cant development in the past decade.
The original Fossil Creek Master Plan (1982) mapped the
100-year fl oodplain and restricted any new development in
this fl oodplain. Construction that occurred throughout the
1990s took place outside the fl oodplain. Early in 2002, the
City of Fort Collins Utilities and Larimer County mapped
a new fl oodplain for this basin as part of a comprehensive
update of the City’s Stormwater Master Plan.
Flooding History
There is a long history of fl ooding along Fossil Creek
which has a drainage basin area of approximately 30 square
miles upstream of Fossil Creek Reservoir. Local newspaper
accounts describe fl oods in 1902, 1938, 1965, 1977 and
1979. During the 1902 fl ood, Fossil Creek Reservoir
reportedly rose 14 feet in 24 hours.
Fossil Creek also fl ooded in 1997 and 1999. Although the
1997 fl ood was considered greater than a 500-year fl ood
(0.2 percent annual-chance fl ood) along Spring Creek, it
was not as large along Fossil Creek. After the 1997 fl ood,
the U.S. Geological Survey studied high water marks to
document the magnitude of fl ooding along Fossil Creek.
The results showed that it was approximately a 50-year
event (2 percent annual-chance fl ood) using the old rainfall
criteria. If the 1997 storm had been located further south,
fl ooding on Fossil Creek would have been much worse.
Basin Problems
The Fossil Creek fl oodplain is now wider in many locations.
Flooding problems are primarily due to undersized culverts
that back water up into homes or overtop roadways.
The majority of fl ooding of structures would occur along
Fossil Creek between the Union Pacifi c Railroad and
Lemay Avenue. Water would back up behind the railroad
embankment south of Trilby Road. The 10-foot-diameter
culvert through the railroad embankment would not be
able to handle the amount of water generated by a fl ood,
and water would back up all the way to the Southridge
Greens Golf Course.
Since the rainfall standard was increased, there are now 117
homes, 13 roads and three railroads that would be damaged
during a 100-year storm, with an estimated $10.6 million
in damage. If nothing is done to mitigate this damage, it is
estimated that $5.97 million of damage would occur over
the next 50 years, primarily from fl ooding of homes.
In addition to fl ooding hazards, erosion has occurred
because of natural processes, agricultural practices and
urban development. The channel of Fossil Creek and its
tributaries are very unstable, with steep banks—in some
places up to 25 feet high. Excessive erosion also leads to
poor water quality, damage to adjacent property, roads
and utilities and reduced biological diversity to support
19
Stormwater Master Plan Executive summary
Recommended Solutions
The recommended plan of improvements was developed to
provide cost-effective solutions to mitigate damages from
the 100-year storm:
Flooding of Homes
• Enlarged culverts at Timberline Road and the Union
Pacifi c Railroad are recommended to address the
fl ooding of homes upstream of the Union Pacifi c
Railroad; and
• Enlarged culverts are recommended at Fossil Ridge Drive
and Hilldale Drive.
The cost is $3.53 million and the benefi t-to-cost ratio is
1.27. Once all improvements are in place, all homes would
be removed from the fl oodplain.
Overtopping of roadways and railroads
• Combination of storage areas and larger culverts are
recommended; and
• Cost is $6.97 million.
Excessive Erosion/Poor Stream Habitat
• Construct sloping boulder drop structures and sloping
back vertical banks, and re-establish native landscaping
to promote biological diversity along the stream.
• Preserve areas with good habitat and enhance areas of
poor habitat.
Excessive erosion, as shown here on Fossil Creek, is a typical problem in many basins.
20
City of Fort Collins Utilities
20
Foothills
About the Basin
The Foothills Basin is centrally located in Fort Collins and
covers about 3,200 acres generally between Taft Hill
and Ziegler Roads and between Horsetooth and Drake
Roads. The basin is mostly developed, with commercial
development along College Avenue and mixed-use
residential in the remainder.
The basin drains from west to east through open channels
or the storm sewer system to the Fossil Creek Reservior
Inlet Ditch. Three irrigation canals intercept stormwater to
transport it out of the basin, but runoff spills into the basin
when canal capacity is exceeded.
Drainage between Taft Hill Road and the Foothills Fashion
Mall is characterized by street and storm sewer fl ow with
some grass-lined channels and detention ponds. The
main channel begins downstream of Stanford Road and
is generally well-defi ned with a low base fl ow. The City
constructed a regional channel east of Timberline Road to
carry stormwater runoff from the entire Foothills Basin.
The original master plan was completed in 1981. The
City of Fort Collins Utilities mapped a new fl oodplain for
the basin as part of a comprehensive update of the City’s
stormwater master plans in early 2003.
Basin Problems
Since the Foothills Basin was developed according to the
original 1981 master plan and the Storm Drainage Design
Criteria, many of the recommended improvements were
completed. Because of this, most of the basin is capable of
handling a 100-year storm event. However, some localized
fl ooding problems exist:
• Warren Farms detention pond located at the northwest
corner of Horsetooth Road and the Burlington
Northern Railroad;
• Nelson Farm detention pond located northwest of the
corner of Lochwood Drive and Horsetooth Road;
• Southmoor Village ponds located near Boltz Drive and
Lemay Avenue; and
• Oxford Apartment pond located near Oxford Lane and
Lemay Avenue.
The master plan update estimates there are 21 structures,
four roads and one railroad crossing that would be damaged
during a 100-year storm, with an estimated $1.5 million in
damages. If nothing is done to mitigate this damage, it is
estimated that $0.91 million of damage would occur over
the next 50 years.
Recommended Solutions
Flood Damage
The recommended selected plan of improvements was
developed to provide cost-effective solutions to mitigate
damages from the 100-year storm and to incorporate the
remaining recommendations from the 1981 master plan.
Projects include:
• Enlarge Nelson Farm, Warren Farms and Southmoor
Village Ponds;
• Connect the Blue Mesa Pond outlet to the Warren
Farms Pond;
21
Stormwater Master Plan Executive summary
Fox Meadows
About the Basin
The Fox Meadows Basin encompasses approximately
2.4 square miles in southeast Fort Collins. The basin is
bound by Horsetooth Road on the north, Lemay Avenue
on the west, Harmony Road on the south and the Cache la
Poudre River on the east. The basin is primarily developed
with residential development, some commercial areas and
Collindale Golf Course. The basin does not include a major
drainageway for conveying fl ows through the basin so no
regulatory fl oodplain has been mapped. Storm runoff fl ows
through a network of storm sewers, local drainage channels
and detention ponds.
Basin Problems
The basin has limited fl ooding problems because it was
developed with the guidance of the Storm Drainage
Design Criteria and the original drainage master plan.
However, the updated master plan identifi ed a few potential
problems. These include overtopping of existing detention
facilities, ponding behind railroad embankments, roadway
overtopping and inadequate ditch capacity. The master plan
estimates 14 structures would be damaged in a 100-year
storm, with $610,000 worth of damage. If nothing is done
to mitigate this damage, an estimated $670,000 worth of
damage could occur over the next 50 years.
Recommended Solutions
Flood Damage
The recommended selected plan of improvements was
developed to provide cost-effective solutions to mitigate
damage from the 100-year storm. Projects include:
• Improve the Fossil Creek Reservoir Inlet Ditch and
bypass structure;
• Construct a detention pond east of the Harmony Mobile
Home Park;
• Enlarge a culvert under Kingsley Drive;
• Enlarge the pond at the corner of Horsetooth and
Ziegler Roads;
• Modify two spillways in the Sunstone Village area; and
• Install a fl ood warning gauge at the railroad embankment
near Golden Meadows.
The total cost is $1.36 million and the benefi t-to-cost ratio
is 0.60. Once all improvements are in place, it is estimated
that four structures will be damaged in a 100-year event.
Stream Stability and Habitat
Habitat enhancement and stream
stability components were not
included in the selected plan since
a natural stream, or drainageway,
does not exist within the basin.
A new fl ood warning gauge is proposed in the Fox Meadows Basin.
22
City of Fort Collins Utilities
22
Mail Creek
About the Basin
The Mail Creek Basin covers about 1,676 acres in southwest
Fort Collins. It is primarily located between Taft Hill Road
and Lemay Avenue and between Horsetooth Road and
County Road 36. The basin is mostly developed, with
commercial development along College Avenue and mixed-
use residential in the remainder of the basin.
The basin generally drains from west to east to the
confl uence of Mail Creek and Fossil Creek and ultimately
to Fossil Creek Reservoir. Three irrigation canals intercept
stormwater to transport it out of the basin, but runoff spills
into the basin when their capacity is exceeded.
Between Taft Hill Road and the Burlington Northern
Railroad, drainage is characterized by street and storm sewer
fl ow with some grass-lined channels and detention ponds.
Two canals drain into Mail Creek east of the railroad. The
main channel of the Mail Creek drainage begins downstream
of College Avenue. East of College Avenue, the channel has
two on-line reservoirs. Below the reservoirs, the channel is
generally well-defi ned with a perennial fl ow.
The original master plan was completed in 1980. The
City of Fort Collins Utilities mapped a new fl oodplain for
the basin as part of a comprehensive update of the City’s
stormwater master plans in late 2002.
Basin Problems
Since the Mail Creek Basin was developed according to the
original 1980 master plan and the Storm Drainage Design
Criteria, many of the recommended improvements were
completed. Because of this, most of the basin is capable of
handling a 100-year storm event. However, some localized
fl ooding problems exist:
• Imperial Estates located in Larimer County northwest of
Taft Hill and Harmony Roads;
• Spills from the canal over the railroad into the Mason
Street area south of Horsetooth Road;
• Undersized culverts under Crest and Hinsdale Streets just
south of Harmony Road; and
• Street fl ooding at County Road 38E and Taft Hill Road,
at Manhattan near the movie theater, and at the area just
north of Larkbunting Drive between Goldeneye and Blue
Mountain Drives.
There are 20 structures, 14 roads and one railroad that would
be damaged during a 100-year storm, with an estimated
$1.1 million in damages. If nothing is done to mitigate this
damage, it is estimated that $700,000 of damage would occur
over the next 50 years.
Recommended Solutions
Flood Damage
The recommended selected plan of improvements was
developed to provide cost-effective solutions to mitigate
damage from the 100-year storm and to incorporate the
remaining recommendations from the 1980 master plan.
Proposed projects:
• Improve canal between Horsetooth and Harmony Roads;
• Acquire the property west of the railroad south of
Harmony Road;
23
Stormwater Master Plan Executive summary
McClellands
About the Basin
The McClellands Basin encompasses approximately 3.4
square miles in southeast Fort Collins. The storm runoff
from the basin originates northeast of College Avenue
and Harmony Road and drains southeast through the
Oakridge, Willow Springs, Stetson Creek and Harvest Park
developments. A single major drainageway, McClellands
Creek, conveys fl ow from the upper end of the basin to
the downstream discharge point along the Fossil Creek
Reservoir Inlet Ditch. The majority of the basin is either
developed, or is being developed, with residential and
commercial land areas.
Basin Problems
The basin has limited fl ooding problems because it was
developed with the guidance of the Storm Drainage Design
Criteria and the original master drainage plan. The updated
master plan identifi es no structures damaged during a
100-year storm. However, several drainage problems have
been identifi ed in the basin, including pond overtopping,
stream instability, water quality and street fl ooding.
Recommended Solutions
Flood Damage
The recommended selected plan of improvements was
developed to provide cost-effective solutions to mitigate the
drainage problems. Proposed projects:
• Modify the pond embankment along County Road 7;
• Construct a spillway through the Union Pacifi c Railroad
embankment at the Oakridge regional detention pond;
• Provide a spillway for the Spring Canyon
Wasteway Ditch;
• Modify the Timber/Stetson Creek Detention Pond;
• Construct additional inlets on Wheaton Drive south of
Oakridge Drive; and
• Modify the overfl ow channel at the Upper Whalers Cove
Detention Pond.
The total cost is $4.3 million and no benefi t-to-cost ratio was
calculated since the proposed projects bring facilities up to
current drainage standards rather than reduce fl ood damage.
Stream Stability and Habitat
The goal is to preserve areas with good habitat and enhance
areas of poor habitat. Projects may include constructing
sloping boulder drop structures, sloping back vertical banks
and re-establishing native vegetation.
An overview of McClellands Creek after improvements.
24
City of Fort Collins Utilities
24
Old Town
About the Basin
The Old Town Drainage Basin is located in north-central Fort
Collins. The basin has a drainage area of approximately 2,120
acres, including approximately 400 acres of the Colorado
State University campus. The entire basin is urbanized, with
some development occurring in the late 1800s.
In general, the basin drains from west to east. The Old Town
Basin receives some runoff water from the Canal Importation
Basin directly west of Old Town. Most of the water from Old
Town drains to the Poudre River, just to the east.
Three major capital projects were completed in Old Town
since the 1997 fl ood: the Howes Street Outfall, the Locust
Street Outfall and the Oak Street Outfall. These projects
signifi cantly reduced fl ooding problems in the basin, and
they removed more than 700 properties from the mapped
fl oodplain. However, in general the projects did not reduce
fl ooding west of Mason Street and many properties remain
in the fl oodplain.
The original master plan for this basin was completed in
1993. In 2002, the City of Fort Collins Utilities mapped a
revised fl oodplain for this area as part of a comprehensive
update of the City’s stormwater master plan.
Flooding History
In the heart of Fort Collins, the Old
Town Basin encompasses the Old
Town business district and surrounding
neighborhoods. Some areas of Old Town
were established in the 1800s when little
thought was given to storm drainage. As
a result, the basin has experienced many
fl oods throughout its history.
Local newspapers have documented
numerous fl oods in Old Town. In 1904,
plugged storm sewer inlets caused a
lake to form on Walnut Street. Again in
1951, storm sewers were overwhelmed
when six inches of rain fell in 27
hours. A small river formed that fl owed
east along Locust and Plum Streets
and fl ooded basements and fi rst fl oors of many homes. In
1961, the local paper noted that a lake formed at College
Avenue and Mulberry Street during a typical rainstorm. This
continues to be a problem today.
Additional noteworthy storms occurred in 1983, 1988, 1992
and 1997. The 1992 fl ood was centered in Old Town and,
according to the CSU rain gauge, two and a half inches fell
in only 30 minutes. Damage to homes and businesses totaled
$438,000 in 1992 dollars and nearly 50 property owners
reported fl ooded basements. The 1997 fl ood in Old Town
occurred the same day as the notable Spring Creek fl ood.
Most attention was focused on Spring Creek, but there also
was severe fl ooding and extensive damage in many parts of
Old Town.
Signifi cant progress has been made in recent years to help
minimize damages. Still, it does not take much rain to
cause signifi cant fl ooding in the Old Town Basin, especially
25
Stormwater Master Plan Executive summary
The remapping of the fl oodplain identifi ed several areas of
fl ood hazard within the basin. During a 100-year storm,
approximately 624 structures would be damaged and nearly
50 street intersections would be fl ooded. This would result
in an estimated $35 million in damages. If nothing is done
to mitigate this damage, it is estimated that $97.5 million
of damage would occur over the next 50 years.
Recommended Solutions
Flood Damage
The recommended selected plan of improvements was
developed to provide cost-effective solutions to mitigate
damages from the 100-year storm. Proposed projects:
• Cherry Street Storm Sewer;
• Laporte Avenue Storm Sewer;
• Whedbee Street Storm Sewer;
• Oak Street Outfall Storm Sewer Extension;
• Magnolia Street Outfall Storm Sewer;
• Myrtle Street Storm Sewer; and
• Mulberry Street / Riverside Avenue Storm Sewer.
The total cost is $50.4 million and the benefi t-to-cost ratio
is 1.41. Once all improvements are in place, damage to
350 structures will be eliminated in a 100-year storm, and
damage will be reduced for the remaining 274 structures.
The recently completed Locust Street Outfall Project is one
of three large capital projects designed to reduce fl ooding
danger in the Old Town Basin.
A series of wetland-based water quality ponds in the Udall Natural Area was part of the Oak Street
Outfall Stormwater Improvement Project completed in 2002.
26
City of Fort Collins Utilities
26
Poudre River
About the Basin
The Cache la Poudre River, a major tributary to the South
Platte River, is located in Larimer and Weld Counties,
with a small portion of the drainage basin extending into
southern Wyoming. Passing through Fort Collins, the
Poudre River corridor provides for stormwater drainage
from various contributing City drainage basins.
Floodplain restrictions have limited the amount of building
in the fl oodplain, resulting in lower development density.
This lower density, combined with sensitivities to the
natural environment, has resulted in a high concentration
of parks and open space along the river corridor. Portions of
the river corridor also contain old industrial sites, refl ecting
a time when the river was seen as a convenient means of
carrying off waste products.
Many of the city’s natural areas are located within the
Poudre River corridor. The riparian ecosystem provides
important habitat for a variety of wildlife and also contains
diverse vegetation that is both biologically and aesthetically
valuable. The biological diversity, along with the sheer
length of mostly undeveloped land, create a critical habitat
of regional signifi cance.
Flooding History
The location of the City of Fort Collins is where it is
today because of fl ooding on the Poudre River. The fi rst
military post, Camp Collins, was originally established
near the present day town of LaPorte. It was destroyed in
1864 when the Poudre River fl ooded. Camp Collins was
relocated to higher ground near present day Old Town in
Fort Collins.
There are several well-documented large fl oods on the
Poudre River around the turn of the century. A fl ood in
1891 was due to a dam break on Chambers Lake. The
most notable fl ood was in 1904. This storm was greater
than a 100-year event and resulted in one death. The
Buckingham, Alta Vista and Andersonville neighborhoods
were severely damaged by the 1904 fl ood.
Numerous other fl oods have occurred on the Poudre River
over time. The most recent fl ood on the Poudre River was a
relatively small one in the spring of 1999. It was caused by
rain and snow runoff during a warm period in April. The
fl ood lasted only a few days, but resulted in a great deal of
bank erosion and threatened many properties.
The Andersonville neighborhood was severely damaged when the
Poudre River fl ooded in 1904. Note the high water mark at the arrow.
27
Stormwater Master Plan Executive summary
Basin Problems
Approximately 3,160 acres of fl oodplain
between Taft Hill Road and I-25 would be
inundated by a 100-year fl ood, damaging
approximately 188 structures. Estimates
indicate that damages to property, utilities
and infrastructure caused by the 100-
year fl ood would total $9.5 million, with
expected annual damages of $460,000.
Additional damages would be expected due to
signifi cant erosion.
Riverbank conditions vary widely both
in terms of their ecological condition and
structural stability. Some sections have stable
banks and a well-developed fl oodplain with
developing riparian zones. Other sections
have been stabilized but are not aesthetically pleasing and
provide little wildlife benefi t. Still other sections have
steep, eroding banks with concrete embankments and
little vegetation.
Recommended Solutions
Multiple alternatives were evaluated for reducing or
eliminating fl ood damage and for controlling erosion.
Projects include:
• improving structures such as levees or channels;
• fl oodproofi ng;
• purchasing fl ood insurance; or
• acquiring property.
The fi nal solution for a particular site would be determined
when the site is targeted for improvement. The total cost
of the projects ranges from $3.8 million to $31.3 million,
depending on the solution chosen at each site. A reasonable
estimate of the total expenditures is approximately $15
million. Benefi t-to-cost ratios vary from less than one to
over fi ve, depending on the project. Once all improvements
are in place, fl ood damage (up to a 100-year storm) to all
188 structures would be eliminated.
The Poudre River in southeast Fort Collins.
28
City of Fort Collins Utilities
28
Spring Creek
About the Basin
Spring Creek is a major watercourse that fl ows from Spring
Canyon Dam at Horsetooth Reservoir to its confl uence
with the Poudre River. The Spring Creek Drainage Basin
encompasses nearly nine square miles in central Fort
Collins. The basin is dominated by residential development
but it also includes open space, parks and isolated areas of
commercial and industrial development.
On July 28, 1997, the city’s worst natural disaster occurred
when Spring Creek fl ooded following 14.5 inches of
rainfall in 31 hours. The impact of the storm would have
been far worse if the City had not invested more than
$5 million in stormwater improvements in the basin in the
early 1990s. These included improvements to channels and
bridges, reinforcement of the Burlington Northern Railroad
embankment, and acquisition and relocation of structures
in high hazard areas (30 mobile homes, nine houses, one
business and one retirement home).
The original Spring Creek master plan was prepared in
1988. The City of Fort Collins Utilities revised the basin’s
fl oodplain as part of a comprehensive update of the City’s
stormwater master plans in late 2002.
Spring Creek is a FEMA-designated fl oodplain and is subject
to the City’s fl oodplain regulations. The new mapping also
includes areas beyond the FEMA fl oodplain which are
considered to be in a City-designated fl oodplain.
Flooding History
Usually an appealing stream adjacent to a popular bike trail,
Spring Creek can change into a torrent of fl oodwaters during
severe storms.
In 1938, when fl oodwater backed up to a width of 200 feet
behind a culvert at Stuart Street, it spilled over the top and
took the road surface with it. In 1961, Prospect Road and
Hospital Road (Lemay Avenue) were fl ooded for the fourth
time that summer, when stormwater overfl owed a 30-inch
storm sewer. Flooding occurred in 1977 and again in 1983,
when a severe storm dropped 2.22 inches of rain in three
hours. Spring Creek backed up, fi lling the basement of a
paint store and washing 10,000 gallons of painting chemicals
into the waterway.
The most devastating fl ood in the basin’s history occurred
in 1997. The Coloradoan reported on “The storm that tore
city’s hearts, homes,” when fi ve residents lost their lives, a
building exploded, a train derailed and 400 people were
rescued from the fl oodwaters. Across the city, over $200
million in damages were attributed to the storm.
Basin Problems
The master plan update identifi ed 178 structures,
eight roads and the Burlington Northern Railroad that
would be damaged during a 100-year storm with an
estimated $8.78 million in damages. If nothing is done
to mitigate this damage, it is estimated that $12.25
million of damage would occur over the next 50 years.
The high water mark indicates the level of fl ood waters on
Spring Creek at Stuart Street during the 1997 storm.
29
Stormwater Master Plan Executive summary
Recommended Solutions
Flood Damage
The recommended plan of improvements was developed to
provide cost-effective solutions to mitigate damages from
the 100-year storm. Projects include:
• Constructing or expanding detention ponds: C&S
Railroad Detention Pond, Rolland Moore Park
Detention, Taft Hill Detention Pond Expansion,
Southwest Regional Park Detention Pond and Dixon
Creek Detention Pond;
• Reinforcing the Burlington Northern
Railroad embankment;
• Stabilizing channel banks along Spring Creek; and
• Improving storm sewers at several intersections, including
Prospect Road and College Avenue, Remington Avenue
and Lake Street, Lake and Center Streets, Riverside
Avenue and Pitkin Street, and Strachan Drive and
Edinburgh Street.
The total cost is $11 million and the benefi t-to-cost ratio is
1.49. Once all improvements are in place, damage to 154
structures will be eliminated in a 100-year storm,
24 structures would be damaged.
Habitat Enhancement
The master plan also includes an assessment of the
creek’s habitat quality and enhancement opportunities.
Enhancements include restoring banks with native
vegetation, removing or modifying manmade barriers to
fi sh passage and restoring portions of the creek to a more
natural formation.
During the 1997 fl ood on Spring Creek, overtopping of the railroad embankment caused a
multiple train car derailment and damage to the Burlington Northern Railroad tracks.
30
City of Fort Collins Utilities
30
West Vine
About the Basin
The West Vine Basin, located in northwest Fort Collins,
extends east from Horsetooth Reservoir to the Cache la
Poudre River and south from West Vine Drive to Mulberry
Street and Laporte Avenue. The total area is approximately
2,350 acres. The eastern half of the basin is part of the Fort
Collins Urban Growth Area and the western half, west of
Overland Trail, includes open space and the Colorado State
University Foothills Campus. Less than 15 percent of the
basin is within city limits; the rest is in Larimer County.
In general, the basin drains from west to east along fi ve
fl ow paths that are not well-defi ned. Throughout the years,
development has occurred over the historical fl ow paths.
Most of the basin’s drainage facilities are inadequate during
any storm event, and as a result, drainage problems have
occurred regularly.
The main channel of the West Vine drainage, downstream
of Laporte Avenue, is usually dry. Several locations lack a
well-defi ned channel because of development and because
stormwater is intercepted by irrigation canals. Only the
reach upstream of Laporte Avenue and Poudre High School
has perennial fl ow in a well-defi ned channel. This reach is
known as Soldier Canyon Creek, and
typically there is a small amount of
base fl ow in the bottom of the channel.
Five irrigation canals cross the basin,
generally from north to south. The
three main canals—the Pleasant Valley
and Lake Canal (PV&L), the New
Mercer Ditch (NMD) and the Larimer
County Canal No. 2 (LC2)—impact
the drainage in the basin. The canals
intercept runoff traveling through the
basin and transport it out. They also
regularly spill runoff into the basin
when their capacity is exceeded.
The original master plan for the West Vine Basin was
completed in 1980. In early 2003, the City of Fort Collins
Utilities and Larimer County mapped a new fl oodplain and
fl oodway for the basin as part of a comprehensive update of
the City’s stormwater master plans.
Flooding History
Development in the basin occurred sporadically over the
years, leaving some areas with small storm sewers while other
areas have no storm sewer system at all. Many houses in the
basin lie within the fl oodplain and have suffered damage
during even relatively small storms.
In 1992, Irish Drive was fl ooded by a storm centered over
Old Town that dropped two and a half inches of rain in less
than an hour. Snowplows were used to push water from Irish
Drive into the irrigation canal. Again in 1994, a storm caused
water to overtop Overland Trail and fl ooded several homes.
In the1997 fl ood, Spring Creek received the most damage,
but considerable destruction also occurred in the West
Vine Basin. Nearly 12 inches of rain fell in two days in the
western portion of the basin. The large lake that formed on
31
Stormwater Master Plan Executive summary
caused an outcry from hard-hit residents for drainage
improvements by the County. Homes in other parts of the
basin also were damaged by this storm.
A slow moving spring rain in 1999 caused signifi cant
fl ooding in the basin when over four inches of rain fell
in a two day period on already rain-soaked ground. The
storm culminated in the second wettest April on record.
Floodwaters reached depths of 18 inches on Hollywood
Street and triggered voluntary evacuations. East of this area,
on Irish Drive, City crews fi lled sandbags and pushed water
into the New Mercer Irrigation Canal with snowplows and
heavy machinery.
Basin Problems
Three main areas in the West Vine Basin have a history
of fl ooding problems. They include the Irish Green
Subdivision, the subdivision at the northwest corner of Taft
Hill Road and Laporte Avenue, and the Second Filing of
the Hanna Subdivision. Residents have indicated there has
been stormwater up to their homes’ foundation levels or
higher on a regular basis. Other reports indicate that the
open fi eld west of the Hanna Subdivision has experienced
ponding during long or intense storms.
Other fl ooded areas include the Bonnaview and Rosteks
Subdivisions and the railroad embankment near Shields
Street and West Vine Drive. Flooding in the Bonnaview
Subdivision resulted from spilling from the PV&L. The
abandoned railroad embankment near Shields and Vine was
overtopped downstream of the existing culvert.
During a 100-year storm, there are 33 structures and 14
roads that would be damaged, in addition to an estimated
18 spills off the Pleasant Valley & Lake Canal, New Mercer
Ditch and Larimer County Canal No. 2. This would result
in an estimated $1.7 million in damages. If nothing is done
to mitigate this damage, it is estimated that $10.4 million
of damage would occur over the next 50 years.
Recommended Solutions
Flood Damage
The recommended plan of improvements was developed to
provide cost-effective solutions to mitigate damages from the
100-year storm. Proposed projects:
• Construct fi ve detention ponds west of Overland Trail and
one east of Taft Hill Road (on the Forney property south
of Vine Drive);
• Construct a channel from the Poudre School District
outfall at Impala Drive and Laporte Avenue, north to the
Irish outfall channel;
• Construct a channel from NMD and Cherry Street to
Taft Hill Road, continuing east under Taft Hill, and LC2
to the West Vine Drive regional detention pond;
• Construct a channel as an outfall from the West Vine
Drive regional detention pond to the Poudre River;
• Construct spill structures on the NMD and LC2; and
• Install new fl ood warning gauge sites.
The total cost is $12.2 million and the benefi t-to-cost ratio
is 1.0. Once all improvements are in place, there will be two
structures damaged in a 100-year storm.
Excessive Erosion/Poor Stream Habitat
The plan proposes channel improvements to improve habitat
City of Fort Collins Utilities, PO Box 580, Fort Collins, CO 80522 • (970) 221-6700 • www.fcgov.com/stormwater
ratings, stream stability and water quality. Improvements
include grading to fl atten out steep bank slopes, the creation
of pools and riffl es and planting native vegetation.
Hollywood Street on July 28 inundated houses with three
to four feet of water before it spilled onto Sunset Street and
the Irish neighborhood. Damages resulting from this event
Flooding in the Irish neighborhood in 1999.
in basements.
Basin Problems
Basin fl ooding results primarily from encroachment and
urbanization of natural drainage corridors, none of which
are visible today. Instead, the streets become stream channels.
When the streets and the undersized storm sewer system
cannot contain the fl ow, water spills out of the street and
fl oods homes and businesses.
This article appeared in the local paper following a 1992 fl ood in Old Town.
• Construct a storm sewer for Imperial Estates;
• Construct a new channel south of Imperial Estates from
the corner of County Road 38E and Harmony Road to
the Westfi eld Park storm sewer; and
• Install fl ood warning gauge sites.
The total cost is $5.4 million and there is no overall benefi t-
to-cost ratio for the basin since the improvements address
localized, not basinwide problems. Once all improvements
are in place, it is estimated no structures will be damaged in
the 100-year event.
Excessive Erosion/Poor Stream Habitat
The plan proposes channel upgrades to improve habitat
ratings, stream stability and water quality. Improvements
include grading to fl atten out steep bank slopes, creating
pools and riffl es, and planting vegetation.
• Extend the pipe at the intersection of Strachan Drive
and Edinburgh Street in the Spring Creek Basin to the
Oxford Lane Pond; and
• Install fl ood warning gauge sites.
The total cost is $2.2 million. There is no overall benefi t-
to-cost ratio for the basin since the improvements address
localized, not basinwide problems. Once all improvements
are in place, it is estimated that 15 structures will be
damaged in a 100-year event.
Excessive Erosion/Poor Stream Habitat
The plan proposes channel upgrades to improve habitat
ratings, stream stability and water quality. Improvements
include grading to fl atten out steep bank slopes, creating
pools and riffl es and planting vegetation.
riparian habitat.
The Fossil Creek master plan recommends enlarging
this culvert at the Union Pacifi c Railroad to reduce
the amount of water that backs up behind the
embankment.
The plan proposes projects to improve stream habitat, stream
stability and water quality by, for example, grading to fl atten
steep banks, creating pools and riffl es and planting vegetation.
Industrial and commercial development along Dry Creek contribute to the
fl ooding potential in the lower and middle basins.
and is found in only a few scattered
locations.
rangeland, irrigated hay meadows and pastures. The majority
of the lower basin is developed for commercial, industrial
and residential uses. The natural channel has disappeared in
some areas of the lower basin due to development.
The 100-year fl oodplain and fl oodway were originally
mapped as part of a FEMA Flood Insurance Study in 1979
and revised in 1996. The original master plan was completed
in 1980. In 2002, the City of Fort Collins Utilities and
Larimer County mapped a revised fl oodplain and fl oodway
for the basin as part of a comprehensive update of the City’s
and County’s stormwater master plan.
Dry Creek is a FEMA-designated fl oodplain and is subject
to City and County fl oodplain regulations.
Flooding History
Although local newspapers reported numerous fl oods over
the last 100 years that affected different areas in and around
Fort Collins, many fl oods in Dry Creek probably went
unnoticed due to the sparse population in the upper basin.
A local resident documented that in 1924 there was fl ooding
that was “belly deep to a horse” in the area that is now
JAX Surplus.
In the fl ood in August 1951, the Coloradoan reported two
breaks in the Eaton Ditch (Larimer and Weld Canal) spilled
is 2.1. Once all improvements are in place, damage to over
635 structures will be eliminated in a 100-year storm and
65 structures still would be damaged.
Environmental Considerations
The plan proposes improvements to stream habitat and
riparian vegetation, enhancing or expanding wetland areas,
maintaining and connecting wildlife travel corridors and
incorporating water quality.
Street fl ooding is more likely to occur in the older parts of
the city than in the more recently developed areas.
the fi re department said they discovered one car fl oating
and some people canoeing on Springfi eld Court.” In 1992,
two and a half inches of rain fell in a little over an hour.
Twenty-fi ve houses in the basin reported damages ranging
from water in basements to main fl oor damage.
Signifi cant street fl ooding is a common problem in the Canal
Importation Basin as shown above near Plum and Aster Streets west
of Colorado State University.
directly east of I-25. The fl ood control projects at Highway
14 and I-25 would still be necessary with the implementation
of a regional master plan.
Preserving and/or enhancing habitat is a goal in
basins with exisiting drainageways.
1−2
2+
of structures.
typically have the largest fl ooding problems. They have
more urban fl oodplains with a signifi cant number of
structures and a larger risk of damage and/or loss of life.
Additionally, open spaces and natural drainageways that can
accommodate fl oodwaters may not be readily available in
these areas. This is the result of paving over or encroaching
upon natural drainageways and waterways.
In 1984, the City of Fort Collins adopted current
stormwater and fl ood protection criteria. As a result,
there is less fl ooding in the more recently developed
southern part of the city. In many cases, drainage criteria
and regulations were in place as well as drainage basin
master plans when development occurred. There are still
some problem areas with undersized drainage structures,
but destructive effects of large storms are reduced due to
design criteria that included buffers and drainage channels
designed with additional capacity. Future development will
be planned utilizing the new, revised fl oodplain studies for
each basin and today’s development criteria.
Stormwater Master Plan Executive Summary Report