HomeMy WebLinkAboutCOUNCIL - AGENDA ITEM - 01/13/2004 - THE PROPOSED 2003 STORMWATER MASTER PLAN DATE: January 13, 2004 STUDY SESSION ITEM
STAFF: Jim Hibbard, Bob Smith, FORT COLLINS CITY COUNCIL
Susan Hayes
SUBJECT FOR DISCUSSION
The Proposed 2003 Stormwater Master Plan.
GENERAL DIRECTION SOUGHT AND SPECIFIC QUESTIONS TO BE ANSWERED
• Does City Council need any additional information before they can consider adoption of the
proposed master plan?
• Does City Council support the current policy of providing 100-year level of protection when
cost effective?
• Are there specific components of the master plan Council would like to see alternatives on?
Executive Summary
In 1999, Council adopted a higher rainfall standard based upon a technical analysis of rainfall
statistics. Higher rainfall results in higher runoff.
In 2001, Council adopted a revised Canal Importation Basin Master Plan and a financing plan to
fund $120 million in stormwater improvements over the next 25 years on a pay-as-you-go basis.
In late 2001, staff initiated a plan to update the master plans for the remaining drainage basins by
the first quarter of 2003. During the remainder of 2003, staff conducted a public outreach program
to inform citizens of proposed plans and compile feedback.
The proposed Stormwater Master Plan Executive Summary Report is attached. The first several
pages contain a summary of citywide information. This is followed by two page summaries of each
basin. The master plan strives to design projects that provide cost-effective flood protection for a
100-year rainfall event. The master plan recommends:
• $164 million in flood control projects split$132 million in the City and$32 million funded
by the County and others,
• $42 million in projects funded by partners(development,grants,etc.)as opportunities arise
for water quality enhancements, and localized drainage improvements,
• standardized development criteria to reduce peak flow leaving newly developed sites to 2-
years historic or equivalent (many basins already had this requirement),
• regional water quality treatment opportunities to improve the quality of stormwater runoff,
and
• expanded wetlands and improved riparian habitat opportunities along natural channels to
improve the quality of stormwater runoff.
The$164 million in flood control projects will reduce flood damages by$290 million over the next
50 years. The number of structures damaged during a 100-year storm will be reduced from 2,600
to 400.
January 13, 2004 Page 2
Staff also estimated the cost of flood control projects required to provide a 50-year level of
protection. 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 the
flood damages and floodplain regulations.
The 50-year protection option has $141 million in flood control projects that will reduce flood
damages by$146 million over the next 50-years. The number of structures damaged during a 100-
year storm will be reduced from 2,600 to 1,500.
Staff recommends Council adopt the 100-year protection plan.
Background and Past Council Direction
The master plan takes a detailed look at the flooding and water quality problems in each basin and
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provides the general direction for stormwater management in those basins. The stormwater master
plan includes:
• Recommended projects to reduce flood damage to homes and businesses, the potential for
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loss of life, as well as reduce flooding of roads,
• guidance for new development in the basin,
• guidance for enhancements to the riparian habitat along stream corridors to improve water
quality, and
• guidance for stabilizing streams where necessary.
The stormwater master plan strives to design projects that provide cost-effective flood protection
for a 100-year rainfall event.
The Master Plan recommends 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.
City Council adopted the original basin master plans from the early 1980's to the early 1990's. The
city constructed numerous projects based on these plans. New development also constructed
drainage facilities in accordance with these master plans.
In 1995, Council adopted a resolution formalizing a strategy to protect and enhance stormwater
quality and to provide a framework to meet federal permit requirements for municipal stormwater
systems. The approach combines appropriate techniques to: 1)prevent pollution on land surfaces;
2) design local drainage systems to treat or mitigate polluted runoff; and 3) protect and restore
aquatic, wetland and stream-side habitats in receiving waters. The drainage master plan integrates
the protection and restoration of aquatic habitat in receiving waters into the technical analyses and
alternatives evaluation. Starting in 2003, the City obtained a stormwater discharge permit to meet
the requirements of the Federal Nation Pollution Discharge Elimination System(NPDES)Phase 11
regulations. Protection and restoration of aquatic habitat in order to improve water quality in
receiving waters are components of this permit.
January 13, 2004 Page 3
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 a lower than 100-year level of flood protection.
Staff has developed and resented to Council a system for prioritizing capital improvement projects.
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Rating criteria is based upon the number of structures removed from the floodplain (damage
reduction and increased safety), the benefit-to-cost ratio (cost effectiveness), and the number of
collector and arterial streets which have water overtopping reduced or eliminated due to a project
(damage reduction and increased safety). The 2004-2005 capital budget recommendations reflected
the use of this system.
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:
• damage could occur to more than 2,600 structures during a 100- ear storm,
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• the estimated damage from a single 100-year storm would be approximately $142 million,
and
• if nothing is done to the existing drainage system,flood damages over the next 50-years are
estimated to be over$353 million.
In addition to structural flood damages, there are also adverse impacts such as personal injury and
loss of life, stream instability, adversely impacted riparian habitat and water quality, road
overtopping, clean-up costs, emotional effects, etc. The master plan does not include any of these
indirect damages.
January 13, 2004 Page 4
The Proposed 2003 Stormwater Mater Plan
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
plan. The first several pages contain a summary of citywide information. This is followed by two
page summaries of each basin. The master plan strives to design projects that provide cost-effective
flood protection for a 100-year rainfall event. The master plan recommends:
• $164 million in flood control projects, $132 million in the City and$32 million funded by
the County and others,
• $42 million in projects funded by partners (development, grants,etc.)as opportunities arise
for water quality enhancements, and localized drainage improvements,
• standardized development criteria to reduce peak flow leaving newly developed sites to 2-
years historic or equivalent (many basins already had this requirement),
• regional water quality treatment opportunities to improve the quality of stormwater runoff
and,
• expanded wetlands and improved riparian habitat opportunities along natural channels to
improve the quality of stormwater runoff.
The overall plan reduces or eliminates 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 plan.
Benefit of $164 Million in Flood Control Projects
Before After
Property Damage Over $353 $63
the Next 50-Years million 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:
• reduced damages to vehicles and public infrastructure,
• reduced emergency response, evacuation, clean-up, temporary housing costs,
• streets are open during flooding events for emergency response vehicles,
• improved water quality, environmental enhancement, and providing a feeling of safety and
security for citizens, and
0 reduced risk of injury and/or loss of life.
January 13, 2004 Page 5
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 $132 million in City funded flood control projects is achievable under the
approved funding plan in approximately 25 years.
The proposed 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 to do so (benefits outweigh the costs). 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.
The analysis identifies damage associated with the 50-year storm and cost-effective projects to
eliminate this damage. 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 the flood damages and floodplain regulations.
The elements of the 100-year level of protection plan were re-sized using the flows estimated from
a 50-year storm. Some basins already have this lower level of protection; therefore, there are no
recommended projects in those basins. In other basins,the proposed improvements are smaller. In
general, projects still include construction or enlargement of detention ponds, construction of open
channels and storm sewers, and enlargement of road culverts.
In the reduced level of protection scenario, $141 million in flood control projects will reduce flood
damages by$146 million over the next 50 years. The number of structures damaged during a 100-
year storm will be reduced from 2,600 to 1,100. 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.
January 13, 2004 Page 6
Reduced Level of Protection Analysis
100-Year Level 50-Year Level
of Protection of Protection
Cost of Flood
Control Projects $ 164 million $ 141 million
Property Damage
Reduced $ 290 million $ 146 million
Number of
Structures -
Damages
Eliminated 12,200 1,500
In addition, the $42 million in projects funded by partners (development, grants, etc.) as
opportunities arise for water quality enhancements,and localized drainage improvements is reduced
to $32 million in the 50-year level of protection scenario.
The 100-year plan provides a higher benefit to cost ratio. The 50-year level of protections does not
reduce the cost as much as might be expected because:
• the 50-year storm flows(and associated pond,channel and pipe sizes)are not one half of the
100-year storm flows, and
• construction of larger projects also derives benefits from economies of scale.
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.
Public Outreach
The process of informing property owners in the City's 12 stormwater basins of upcoming changes
to both the master plan 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.
These customers received a packet that included comprehensive information about:
• floodplain mapping,
• the review process for floodplain regulations, and
• the impacts on property mapped within the floodplains.
January 13, 2004 Page 7
Each property owner/renter also received:
• an individualized floodplain map showing their property relative to the floodplain,
• a flood history for their basin, and
• property protection information.
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
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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.
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:
• flooding histories for each basin,
• maps showing identified basin problems,
• maps showing proposed solutions,
• proposed floodplain regulations,
• stormwater project funding, and
• 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 plan or floodplain regulations, almost everyone
got a chance to express their views to staff.
January 13, 2004 Page 8
Comments received on master plan issues can generally be summarized as follows:
• support for specific projects, build as soon as possible,
• support for the master plan as a whole, it seems reasonable,
• questions about local drainage issues,
• make sure water quality is an integral part of capital projects,
• concern projects don't encourage mosquitoes,
• support for the 100-year level of protection,
• do more to protect citizens,
• the master plan is too expensive, flooding is rare,
• balance habitat protection with recreational users,
• keep streams natural, not structural,
• questions about impact of recent nearby development,
• concern that projects remove vacant land from the floodplain, which allows development,
and
• would like to see funding changed back to basin by basin, floodplain properties should pay
more.
ATTACHMENTS
Stormwater Master Plan Executive Summary Report
Stormwater Master Plan
Executive Summarq Report
September 2003
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City of Fort Collins Utilities _
Acknowledgments
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
r
II
StoYntb oterMaster Nor Executive Sorrinloly
Table of contents
Acknowledgments
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
1 • Fox Meadows 21
• Mail Creek 22
• McClellands 23
• Old Town 24
• Poudre River 26
• Spring Creek 28
• West Vine 30
1 III
City of Fort C01101S UtilitieS _
Stoymwater Master PEan Executive Summary Report
Master planning enables the City of Fort Collins Utilities to Do nothing—includes enforcing our existing
identify stormwater management issues and create solutions floodplain regulations, development criteria and
to potential flood risks. Master plans provide: utilizing our floodwarning system, but does not include
projects to reduce flood damages.The goal is to keep
• Proposed projects to reduce flood damage to homes damages at current levels;
and businesses;
• Purchase properties in the floodplain—reduces the
• Proposed projects to reduce flooding of roads; damages by removing structures in the floodplain, but
• Guidance for new development; does not change the floodplain;
• Guidance for enhancements to the riparian habitat Evacuate the water faster—includes building bigger
along stream corridors; channels and pipes to drain water faster and reduce the
• Improvements to water quality; and floodplain,thereby reducing flood damages;
• Guidance for stabilizing streams where necessary. Slow the water down—uses detention ponds to control
water and slow it down to fit into the channels and
Master plans are conceptual and serve to provide the pipes downstream, thereby reducing flood damages;or
general direction for stormwater management within the
• A combination of any or all of the above.
basin. Some of the factors considered in development of
master plans include: Prior to the 1960s, drainage facilities, such as storm sewers
Flood control, and street gutters, often were designed to accommodate
• minor storms that might occur every few years.
• Cost effectiveness, Consequently,during major storms, neighborhoods and
• Development criteria commercial areas in the oldest sections of Fort Collins
• Water quality, typically have the largest flooding problems.They have
more urban floodplains with a significant number of
• Riparian habitat and structures and a larger risk of damage and/or loss of life.
• Stream stability. Additionally,open spaces and natural drainageways that can _
Strategies for reducing flood damage typically include accommodate floodwaters may not be readily available in
detention facilities, storm sewers, culverts, open channels these areas.This is the result of paving over or encroaching
and stream improvements. Enhancement of habitat and upon natural drainageways and waterways.
environmental corridors are an important consideration In 1984,the City of Fort Collins adopted current
in planning for these projects. In some basins,excessive stormwater and flood protection criteria.As a result, _
erosion and unstable, steep banks compromise water there is less flooding in the more recently developed
quality and habitat.When appropriate, proposed southern part of the city. In many cases,drainage criteria
solutions include improvements that incorporate water and regulations were in place as well as drainage basin
quality, enhancements or expansion to wetland areas, as master plans when development occurred.There are still
well as stream habitat and riparian vegetation. some problem areas with undersized drainage structures,
Projects and solutions to flood damage within a basin but destructive effects of large storms are reduced due to
are developed by evaluating a number of approaches design criteria that included buffers and drainage channels
and alternative strategies. Each approach is evaluated for designed with additional capacity. Future development will
effective strategies to decrease flood risk and damages. be planned utilizing the new, revised floodplain studies for
The basic approaches to finding solutions to flood each basin and today's development criteria.
damages include:
An extensive public outreach program which
included basin-specific open houses and
individual mailings, began in 2002 to inform
citizens and gather public comment
New Rainfall Standards new development.These buffer limits help minimize the
potential damage associated with active channel erosion and
Following the devastating flood of 1997 , the City of Fort encroachment of future development.
Collins embarked on a study to re-evaluate the amount
of rainfall associated with the 100-year frequency storm. Citywide Problems and Solutions
A Precipitation Study Task Force,with members from
regulatory agencies, technical fields and private citizens, Studies indicate that significant problems are found in a
variety of locations around the city.The citywide problems
provided the guidance for the study.
and solution maps provide a summary of the problems
' In 1999, City Council adopted the new rainfall standards and recommended solutions (pages 7-10).The following
to be used in the design of stormwater facilities in the city. statistics are based on the conclusions of the Technical
The old standard of 2.89 inches over a two-hour period Drainage Master Plan Reports:
was revised to 3.67 inches for the 100-year design storm. More than 2,600 structures could be damaged during
Because of the new 100-year standard, standards for the more a 100-year storm;
frequent storms and the 500-year storm were revised as well. The estimated damage from a 100-year storm,
Development Guidance if no improvements are made, is approximately
$141.6 million;
' Together with floodplain regulations, the master plans also If nothing is done to reduce damages over the next
provide guidance for new development in order to prevent 50 years,flood damages are estimated to be over
additional flood problems. $353 million;
In the future, the City of Fort Collins Storm Drainage The estimated total cost for all proposed stormwater
Design Criteria and Construction Standards will guide management improvements is approximately
design and implementation of all stormwater conveyance $210 million (proposed projects which reduce damages
facilities. In general,new development will be required to to homes and businesses is$164 million);
have on-site detention to reduce the peak flow leaving the The estimated amount of damage reduction from
site.These detention ponds will typically provide a water these proposed improvements is approximately
quality component in order to treat some of the runoff before $290 million; and
it leaves the site. Damages would be eliminated on approximately
2,200 structures, almost 85%of the total number
In addition,adherence to erosion buffer limits,developed of structures.
along many of the natural streams, is recommended for all
'! 5
City of Fort Collins Utilities
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 9 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
Each basin has unique characteristics, including physical studies involve basin inspections, hydrology(amount
topography, land uses (both existing uses and potential for of flow) and hydraulic analyses (flow paths),problem
future development) and the presence of drainage channels identification, alternatives analysis and a recommended
and drainage pathways.These characteristics are evaluated plan for improvements.
in the technical studies conducted for each basin. Basin
1rt
Mountain Avenue, above, is an area where the street
becomes the stream channel. At right is a natural stream
in a rural area.
1 Stormwater-Master Plan ExeCutive Summary
Fort Collins Stormwater Drainage Basins
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City of Fort Collins Utilities
Boxelder Creek and Storm runoff from the upper 186 square miles of the
basin is controlled by a series of flood control reservoirs.
Cooper Slough However,the lower 80 square miles of the basin can -
About the Basins generate a substantial amount of runoff contributing to
flooding along Boxelder Creek and Cooper Slough on both
The Boxelder Creek and Cooper Slough Basins sides of I-25.A portion of this runoff crosses 1-25 through
encompass approximately 265 square miles beginning at the Latimer and Weld Canal and also contributes to
the Colorado/Wyoming border, extending southward into flooding problems on the west side of the interstate.
east Fort Collins and ending at the Cache la Poudre River.
The basins are primarily characterized by farmland with Flooding History _
isolated areas of mixed-use residential development and Major floods occurred in these basins in 1909, 1922, 1930,
limited commercial development. 1937, 1947, 1963, 1967 and 1969. In 1947, a Coloradoan _
These basins are interconnected. Floodwaters from newspaper headline read, "Violent Rainstorm Floods Large
Boxelder Creek Basin can spill into Cooper Slough Basin Area; Crop Losses Heavy."As much as five inches of rain
upstream of Vine Drive. Most of the water from Cooper fell northwest of Wellington,washing out bridges and --
Slough drains into Boxelder Creek at Prospect Road,near flooding crops. Nearly 1,000 acres of grain, alfalfa and corn
the downstream end of the basins. crops were damaged. Heavy rains caused Boxelder Creek to
overflow its banks again in 1967 and resulted in the death
Latimer County and the City of Fort Collins prepared of a mother and her three daughters who drove into the
the original floodplain study in 1981. In the later part of flooded creek where it passed over a county road southeast _
2002,Fort Collins Utilities,in cooperation with Latimer of Wellington. Floods that summer destroyed county
County,revised the floodplain map for the basins as bridges seven times.
part of a comprehensive update of the City's stormwater
master plans.
In a rural area of Boxelder creek, concrete rubble is used to sta-
bilize the bank from further erosion.
Basin Problems • Box culvert in the business park north of Highway 14;
The master plan update estimated that 134 structures - Box culvert under Highway 14 for Cooper Slough;
would be damaged during a 100-year storm with the most • Channelization of Cooper Slough and Lake Canal south of
significant structural damage at the State Highway 14 and Highway 14 to Boxelder Creek; and
I-25 intersection.There are also 18 roads within the basin . Box culvert under Prospect Road at Boxelder Creek.
that would be overtopped during a 100-year storm.The
master plan estimated that there would be$23 million in These projects would prevent 91 structures from being
damages during a 100-year storm. If nothing is done to damaged and eliminate two roads from overtopping in a 100-
mitigate this damage, it is estimated that$62 million of year storm.The total cost is $19.2 million and the benefit-to-
damage would occur over the next 50 years. cost ratio is 3.26.Approximately 43 structures would still be
In addition to flooding hazards,erosion has occurred damaged in the 100-year storm.
because of natural processes,agricultural practices and Stream stability and Habitat
urban development. Excessive erosion leads to poor water
quality,damage to adjacent property, roads and utilities and The master plan also recommends opportunities to enhance
reduced biological diversity to support riparian habitat. the riparian habitat and address erosion along Boxelder
Creek.This includes constructing sloping boulder drop
Recommended Solutions structures, sloping back vertical banks and re-establishing
The recommended selected plan of improvements native landscaping to promote biological diversity along the
stream.The goal is to preserve areas with good habitat and
was developed to provide cost-effective solutions to
' mitigate damages from the 100-year storm. Most of the enhance areas of poor habitat.
recommended improvements are located at the northwest New Development Guidance
and southwest corners of Highway 14 and 1-25,where the
majority of the existing damage to structures is anticipated. Another important aspect of the master plan is to provide
The improvements include: guidance for new development.The plan recommends that
two corridors in the basin be further studied to address
needed drainage infrastructure. The first corridor is east
of 1-25 in the Boxelder Creek Basin.The second corridor
is located north of the Latimer and Weld Canal within the
Cooper Slough Basin, known as the Mountain Vista subarea.
Regional Opportunities
The Boxelder Creek floodplain also impacts the towns
of Wellington and Timnath, as well as a large amount of
sparsely developed and undeveloped property east of 1-25.
The County and the City,along with the other affected
v
communities and landowners,will persue a regional master
plan for the basin.This plan could reduce the size of the
floodplain by constructing additional flood detention in
the basin or channeling the Boxelder Creek overflow path
directly east of 1-25.The flood control projects at Highway
14 and I-25 would still be necessary with the implementation
L of a regional master plan.
Preserving and/or enhancing habitat is a goal in
basins with exisiting drainageways.
13
City or Fort Collins Utilities
Canal Importation campus and Old Town area.The basin has experienced
flooding many times due to its urban nature and because
About the Basin surrounding development took place in the 1950s, prior to
a stormwater drainage program. ^
The Canal Importation Drainage Basin spans nearly five
square miles in west-central Fort Collins.Three major In September 1938, over four and a half inches of rain fell
irrigation canals traverse the basin from north to south and in 48 hours west of town and caused widespread damage.
impact drainage in the basin.The canals can intercept runoff The Evening Courier reported, `Although almost all ditches
traveling through the basin and transport it out of the basin, had to be shut off at the river to keep them from breaking
and they also spill runoff into the basin when their capacity their banks,drainage kept most of them full." More
is exceeded. flooding occurred in August 1951,when over six inches
of rain fell in 27 hours,with slightly more than one inch
The basin,which suffered significant property damage falling in 15 minutes.The Fort Collins Coloradoan reported,
in the flood of 1997,is almost completely urbanized with "Mr.Wilkinson said the New Mercer, Latimer County _
primarily mixed density residential and isolated commercial No. 2 and Arthur Ditches west of Fort Collins did not have
land uses. Runoff from the basin empties into the Old Town any breaks. However, `pick-ups' from flash floods caused
and Spring Creek Basins. all of them to overflow, the water flooding the Colorado
Much development in the basin occurred before the City A&M college campus." _
adopted drainage criteria.The basin's original master plan, During the morning of August 13, 1975, the basin received
prepared in 1980, identified several drainage improvement nearly four inches of rain.The Coloradoan reported, "The
projects. Many of these projects have been completed or are hardest hit section apparently was near Avery Park where
in the process of being constructed, including the Sheldon the fire department said they discovered one car floating
Lake Drainage Improvement Project, Canal Importation and some people canoeing on Springfield Court." In 1992,
Channel,Fairbrooke Detention Pond, Rodeo Detention two and a half inches of rain fell in a little over an hour.
Pond,Willow Lane Channel,Plum Street Regional Twenty-five houses in the basin reported damages ranging
Detention Pond and a spill structure and outlet pipe at from water in basements to main floor damage.
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.
1
In 2000, the City of Fort Collins Utilities
�I
mapped a new floodplain for this area as part of
a comprehensive update of the basin's stormwater
master plan.
Flooding History °
During storms,water from the west flows into the
three irrigation canals until they fill up and spill H r "
where the banks are low. Floodwaters travel east
until they reach the Colorado State University
Significant street Gooding is a common problem in the Canal
Importation Basin as shown above near alum and Aster Streets west
of Colorado state university.
Flooding in July 1997 caused significant damage through-
out the Canal Importation Basin. Water flooded_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 flooding ever seen in
the area.A storm in April 1999 also caused some minor
flooding damage to homes in the basin.
Basin Problems `
Flooding potential in the basin continues to be widespread, Street flooding is more likely to occur in the older parts of
due to significant loss of natural drainage channels and the city than in the more recently developed areas.
uncontrolled spilling of storm runoff from the canals.
A 100-year storm event would result in more than 700 constructing larger culverts under roads and storm sewers
structures being flooded with total damages estimated at to drain neighborhoods, building open channels and
$25.6 million. If nothing is done to mitigate this damage, modifying some of the irrigation canals to carry more
it is estimated that$125 million of direct flood damage stormwater runoff
would occur over the next 50 years. • Detention Ponds: Sheldon Lake, City Park Nine Golf
During a 100-year storm, there is significant street and Course,West Orchard,Glenmoor,West Prospect,
neighborhood flooding,severely impeding traffic and Fairbrooke, Kane and Red Fox Meadows;
' placing citizens and emergency responders at risk. • Road Culverts:Taft Hill Road,Skyline Drive, Hampshire
• Taft Hill Road would be overtopped at five locations; Road,Langshire Drive, Stuart Street and Hillcrest Drive;
' • Shields Street, Prospect Road and Overland Trail would • Storm Sewers: Mulberry Street,Cook Drive, Plum
be overtopped at several locations; Channel(south of Orchard Place),Elizabeth Street,
Prospect Road/Overland Trail, Drake Road to
• Significant street flooding would occur along West Spring Creek;
Elizabeth,West Mulberry, Mountain and Oak Streets;
• Open Channels: parallel channel to the west of the
' Many other collector and local streets would be flooded Pleasant Valley and Lake Canal from Stuart Street to
or overtopped; and Drake Road;and
• Entire neighborhoods could be flooded. • Irrigation Canals: Pleasant Valley and Lake Canal from
Prospect Road to Fairbrooke Channel and New Mercer
Recommended Solutions Ditch from Elizabeth Street to south of Prospect Road.
In 2001, Council adopted the Canal Importation Basin The total cost is$51.5 million and the benefit-to-cost ratio
Master Plan. Some projects have been completed or are is 2.1. Once all improvements are in place, damage to over
underway.The following information represents the 635 structures will be eliminated in a 100-year storm and
information adopted by Council. 65 structures still would be damaged.
1 Flood Damage Environmental Considerations
The recommended plan of improvements was developed The plan proposes improvements to stream habitat and
' to provide cost-effective solutions to mitigate flood damage riparian vegetation,enhancing or expanding wetland areas,
from the 100-year storm.The plan includes building maintaining and connecting wildlife travel corridors and
detention ponds where possible to slow the water down, incorporating water quality.
15
City of Fort Collins Utilities
Dry Creek rangeland, irrigated hay meadows and pastures.The majority _
of the lower basin is developed for commercial, industrial
About the Basin and residential uses.The natural channel has disappeared in
some areas of the lower basin due to development.
Dry Creek,a tributary to the Poudre River,extends from
near the Wyoming border to where it joins the river near The 100-year floodplain and floodway were originally
Mulberry Street and Timberline Road.The Dry Creek mapped as part of a FEMA Flood Insurance Study in 1979 _
Basin is approximately 23 miles long and six miles wide, and revised in 1996.The original master plan was completed
encompassing approximately 62 square miles.The upper in 1980. In 2002, the City of Fort Collins Utilities and
and middle portions of the basin are primarily used as Latimer County mapped a revised floodplain and floodway for the basin as part of a comprehensive update of the City's
R and County's stormwater master plan.
li Dry Creek is a FEMA-designated floodplain and is subject
`# to City and County floodplain regulations.
,.r
` Flooding History
Although local newspapers reported numerous floods over
the last 100 years that affected different areas in and around
Fort Collins, many floods in Dry Creek probably went
t
14
unnoticed due to the sparse population in the upper basin. - -
""� A local resident documented that in 1924 there was flooding
' that was"belly deep to a horse" in the area that is now
JAX Surplus.
In the flood in August 1951, the CoLoradoan reported two
breaks in the Eaton Ditch (Latimer and Weld Canal) spilled
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 Creekjoins the Poudre
River. Today, the channel has been severely
altered by development and agriculture y
and is found in only a few scattered ,
locations. ti �Y�
' over into Dry Creek and"flooded
tourist camps,stores and houses
on the west side of North College
Avenue north of City limits." In
the same storm, another 20 houses
' flooded 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, flooding basements north
of town, most likely in the Dry
Creek Basin.
In spite of the small number of
reported floods in the Dry Creek
Basin, it contains a very large Industrial and commercial development along Dry Creek contribute to the
drainage area and significant flooding potential in the lower and middle basins.
flooding could occur at any time.
Recommended Solutions
Basin Problems
Flood Damage
' While there is no documented history of flooding in the
upper and middle portions of the basin,a large storm could The improvement plan was developed to provide cost-
threaten the lower basin. In the lower basin, there are 614 effective solutions to mitigate flood damage from a 100-year
structures, nine roads, Latimer and Weld Canal and one storm. Projects include:
railroad that would be damaged during a 100-year storm
event,with an estimated$24.4 million in damage. If nothing Dry Creek Flood Control Project: a combination' e is done to mitigate this damage,it is estimated that $21.6 Projects in the upper,middle and lower basins to reduce
million of damage would occur over the next 50 years. the amount of flooding. Projects include modifications to
Douglas Reservoir Dam, construction of three detention
Minor flooding has occurred in the lower portion of the ponds, installation of a SCADA system,construction of an
basin due to inadequate or non-existent drainage facilities. irrigation water supply pipeline from Latimer County Canal
Areas south of the Latimer and Weld Canal would be to the Terry Lake Inlet Ditch and construction of open
flooded if the canal were overtopped during a large storm. channels to carry the flow to the Poudre River; and
Areas of potential flooding include, but are not limited to:
• Lower basin: a combination of projects to help solve local
1 Airpark business area, including the runway and flooding problems. Projects include the Lemay Channel,
several hangars; Lincoln Channel and College Avenue storm sewer.
' Several mobile home parks and neighborhoods; The total cost is$25.2 million and the benefit-to-cost ratio is
1.04. When all improvements are in place, it is estimated that
• Vine Drive, College Avenue, Lemay Avenue and no structures will be damaged in the 100-year storm.
' Mulberry Street;and
Excessive Erosion/Poor Stream Habitat
• The intersection of Redwood and Conifer Streets.
' The plan proposes projects to improve stream habitat,stream
stability and water quality by, for example,grading to flatten
steep banks, creating pools and riffles and planting vegetation.
17
City of Fort Collins Utilities
Fossil Creek embankment south of Trilby Road.The 10-foot-diameter
culvert through the railroad embankment would not be
About the Basin able to handle the amount of water generated by a flood,
and water would back up all the way to the Southridge
The Fossil Creek Drainage Basin extends along the south Greens Golf Course.
end of Fort Collins, from the foothills across Interstate 25
past County Road 5. It encompasses 32 square miles in Since the rainfall standard was increased, there are now 117
the city of Fort Collins and Latimer County. Historically, homes, 13 roads and three railroads that would be damaged
the basin consisted of agricultural land, but the basin has during a 100-year storm,with an estimated$10.6 million
experienced significant development in the past decade. in damage. If nothing is done to mitigate this damage, it is
estimated that$5.97 million of damage would occur over
The original Fossil Creek Master Plan (1982) mapped the the next 50 years, primarily from flooding of homes.
100-year floodplain and restricted any new development in
this floodplain. Construction that occurred throughout the In addition to flooding hazards, erosion has occurred
1990s took place outside the floodplain. Early in 2002,the because of natural processes,agricultural practices and
City of Fort Collins Utilities and Latimer County mapped urban development.The channel of Fossil Creek and its -
a new floodplain for this basin as part of a comprehensive tributaries are very unstable,with steep banks—in some
update of the City's Stormwater Master Plan. places up to 25 feet high. Excessive erosion also leads to
poor water quality,damage to adjacent property, roads
Flooding History and utilities and reduced biological diversity to support
riparian habitat.
There is a long history of flooding along Fossil Creek -
which has a drainage basin area of approximately 30 square
miles upstream of Fossil Creek Reservoir. Local newspaper
accounts describe floods in 1902, 1938, 1965, 1977 andr-
1979. During the 1902 flood, Fossil Creek Reservoir
reportedly rose 14 feet in 24 hours.
Fossil Creek also flooded in 1997 and 1999.Although the
1997 flood was considered greater than a 500-year flood
(0.2 percent annual-chance flood) along Spring Creek,it
was not as large along Fossil Creek.After the 1997 flood,
the U.S. Geological Survey studied high water marks to it
document the magnitude of flooding along Fossil Creek. 1, -
The results showed that it was approximately a 50-year
event (2 percent annual-chance flood) using the old rainfall
criteria. If the 1997 storm had been located further south,
flooding on Fossil Creek would have been much worse. The Fossil Creek master plan recommends enlarging
this culvert at the Union Pacific Railroad to reduce the
Basin Problems amount of water that backs up behind the embank-
ment.
The Fossil Creek floodplain 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 flooding of structures would occur along
Fossil Creek between the Union Pacific Railroad and
Lemay Avenue.Water would back up behind the railroad
18
Stormivoter Moster Plon Executive Ste�ru'nary
flit-
Excessive erosion, as shown here on Fossil Creek, is a typical problem in many basins.
' Recommended Solutions Overtopping of roadways and railroads
' The recommended plan of improvements was developed to • Combination of storage areas and larger culverts are
provide cost-effective solutions to mitigate damages from recommended;and
the 100-year storm: • Cost is$6.97 million.
Flooding of Homes Excessive ErosionlToor Stream Habitat
• Enlarged culverts at Timberline Road and the Union • Construct sloping boulder drop structures and sloping
' Pacific Railroad are recommended to address the back vertical banks, and re-establish native landscaping
flooding of homes upstream of the Union Pacific to promote biological diversity along the stream.
Railroad; and
' Preserve areas with good habitat and enhance areas of
• Enlarged culverts are recommended at Fossil Ridge Drive poor habitat.
and Hilldale Drive.
The cost is$3.53 million and the benefit-to-cost ratio is
1.27. Once all improvements are in place,all homes would
be removed from the floodplain.
19
City of Fort Collins Utilities
Foothills • Southmoor Village ponds located near Boltz Drive and _
Lemay Avenue;and
About the Basin • Oxford Apartment pond located near Oxford Lane and
The Foothills Basin is centrally located in Fort Collins and Lemay Avenue.
covers about 3,200 acres generally between Taft Hill The master plan update estimates there are 21 structures,
and Ziegler Roads and between Horsetooth and Drake four roads and one railroad crossing that would be damaged
Roads.The basin is mostly developed,with commercial during a 100-year storm,with an estimated$1.5 million in
development along College Avenue and mixed-use damages. If nothing is done to mitigate this damage, it is
residential in the remainder. estimated that$0.91 million of damage would occur over
The basin drains from west to east through open channels the next 50 years.
or the storm sewer system to the Fossil Creek Reservior Recommended solutions —
Inlet Ditch.Three irrigation canals intercept stormwater to
transport it out of the basin,but runoff spills into the basin Flood Damage
when canal capacity is exceeded.
The recommended selected plan of improvements was
Drainage between Taft Hill Road and the Foothills Fashion developed to provide cost-effective solutions to mitigate
Mall is characterized by street and storm sewer flow with damages from the 100-year storm and to incorporate the
some grass-lined channels and detention ponds.The remaining recommendations from the 1981 master plan.
main channel begins downstream of Stanford Road and Projects include:
is generally well-defined with a low base flow.The City
constructed a regional channel east of Timberline Road to ' Enlarge Nelson Farm,Warren Farms and Southmoor
carry stormwater runoff from the entire Foothills Basin. Village Ponds;
• Connect the Blue Mesa Pond outlet to the Warren
The original master plan was completed in 1981.The Farms Pond;
City of Fort Collins Utilities mapped a new floodplain for
the basin as part of a comprehensive update of the City's • Extend the pipe at the intersection of Strachan Drive
stormwater master plans in early 2003. and Edinburgh Street in the Spring Creek Basin to the
Oxford Lane Pond; and
Basin Problems • Install flood warning gauge sites.
Since the Foothills Basin was developed according to the The total cost is$2.2 million.There is no overall benefit-
original 1981 master plan and the Storm Drainage Design to-cost ratio for the basin since the improvements address
Criteria, many of the recommended improvements were localized, not basinwide problems. Once all improvements
completed. Because of this,most of the basin is capable of are in place, it is estimated that 15 structures will be
handling a 100-year storm event. However,some localized damaged in a 100-year event.
flooding problems exist:
Excessive Erosion/Poor Stream Habitat
• Warren Farms detention pond located at the northwest
corner of Horsetooth Road and the Burlington The plan proposes channel upgrades to improve habitat
Northern Railroad; ratings, stream stability and water quality. Improvements
include grading to flatten out steep bank slopes, creating
• Nelson Farm detention pond located northwest of the pools and riffles and planting vegetation.
corner of Lochwood Drive and Horsetooth Road;
^n
Lt{
Ste MMIter McWer Plan Lae ,: sW1101( ,
1 Fox Meadows storm,with $610,000 worth of damage. If nothing is done
to mitigate this damage,an estimated$670,000 worth of
About the Basin damage could occur over the next 50 years.
The Fox Meadows Basin encompasses approximately Recommended Solutions
2.4 square miles in southeast Fort Collins.The basin is
bound by Horsetooth Road on the north, Lemay Avenue Flood Damage
on the west, Harmony Road on the south and the Cache la The recommended selected plan of improvements was
Poudre River on the east.The basin is primarily developed developed to provide cost-effective solutions to mitigate
with residential development,some commercial areas and damage from the 100-year storm. Projects include:
Collindale Golf Course.The basin does not include a major
drainageway for conveying flows through the basin so no • Improve the Fossil Creek Reservoir Inlet Ditch and
regulatory floodplain has been mapped. Storm runoff flows bypass structure;
through a network of storm sewers, local drainage channels . Construct a detention pond east of the Harmony Mobile
and detention ponds. Home Park;
' Basin Problems • Enlarge a culvert under Kingsley Drive;
The basin has limited flooding problems because it was • Enlarge the pond at the corner of Horsetooth and
developed with the guidance of the Storm Drainage Ziegler Roads;
Design Criteria and the original drainage master plan. • Modify two spillways in the Sunstone Village area;and
However, the updated master plan identified a few potential . Install a flood warning gauge at the railroad embankment
problems.These include overtopping of existing detention near Golden Meadows.
facilities,pending behind railroad embankments,roadway
The total cost is $1.36 million and the benefit-to-cost ratio
overtopping and inadequate ditch capacity.The master plan is 0.60. Once all improvements are in place,it is estimated
estimates 14 structures would be damaged in a 100-year 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 flood warning gauge is proposed in the Fox Meadows Basin.
' 21
City of Fort Collins Utilities
Mail Creek • Undersized culverts under Crest and Hinsdale Streets just
south of Harmony Road;and
About the Basin • Street flooding at County Road 38E and Taft Hill Road,
The Mail Creek Basin covers about 1,676 acres in southwest at Manhattan near the movie theater,and at the area just
Fort Collins. It is primarily located between Taft Hill Road north of Larkbunting Drive between Goldeneye and Blue
and Lemay Avenue and between Horsetooth Road and Mountain Drives.
County Road 36.The basin is mostly developed,with There are 20 structures, 14 roads and one railroad that would
commercial development along College Avenue and mixed- be damaged during a 100-year storm,with an estimated
use residential in the remainder of the basin. $1.1 million in damages. If nothing is done to mitigate this
damage, it is estimated that$700,000 of damage would occur
The basin generally drains from west to east to the over the next 50 years.
confluence of Mail Creek and Fossil Creek and ultimately
to Fossil Creek Reservoir.Three irrigation canals intercept Recommended Solutions
stormwater to transport it out of the basin, but runoff spills Flood Damage
into the basin when their capacity is exceeded.
The recommended selected plan of improvements was
Between Taft Hill Road and the Burlington Northern developed to provide cost-effective solutions to mitigate _
Railroad, drainage is characterized by street and storm sewer damage from the 100-year storm and to incorporate the
flow with some grass-lined channels and detention ponds. remaining recommendations from the 1980 master plan.
Two canals drain into Mail Creek east of the railroad.The Proposed projects: --
main channel of the Mail Creek drainage begins downstream
of College Avenue. East of College Avenue, the channel has ' Improve canal between Horsetooth and Harmony Roads;
two on-line reservoirs. Below the reservoirs, the channel is • Acquire the property west of the railroad south of
generally well-defined with a perennial flow. Harmony Road;
The original master plan was completed in 1980.The • Construct a storm sewer for Imperial Estates;
City of Fort Collins Utilities mapped a new floodplain for • Construct a new channel south of Imperial Estates from
the basin as part of a comprehensive update of the City's the corner of County Road 38E and Harmony Road to
stormwater master plans in late 2002. the Westfield Park storm sewer;and
Basin Problems • Install flood warning gauge sites.
The total cost is $5.4 million and there is no overall benefit-
Since the Mail Creek Basin was developed according to the to-cost ratio for the basin since the improvements address
original 1980 master plan and the Storm Drainage Design localized,not basinwide problems. Once all improvements
Criteria, many of the recommended improvements were are in place, it is estimated no structures will be damaged in
completed. Because of this, most of the basin is capable of the 100-year event.
handling a 100-year storm event. However,some localized
flooding problems exist: Excessive Erasion/Poor Stream Habitat
• Imperial Estates located in Latimer County northwest of The plan proposes channel upgrades to improve habitat
Taft Hill and Harmony Roads; ratings,stream stability and water quality. Improvements -
• Spills from the canal over the railroad into the Mason include grading to flatten out steep bank slopes,creating
Street area south of Horsetooth Road; pools and riffles, and planting vegetation.
2
StOMRVC)ter Master Plan Executive scar'Io�-,�r;
Mcdellands Basin Problems
About the Basin The basin has limited flooding problems because it was
developed with the guidance of the Storm Drainage Design
The McClellands Basin encompasses approximately 3.4 Criteria and the original master drainage plan.The updated
square miles in southeast Fort Collins.The storm runoff master plan identifies no structures damaged during a
from the basin originates northeast of College Avenue 100-year storm. However, several drainage problems have
and Harmony Road and drains southeast through the been identified in the basin, including pond overtopping,
Oakridge,Willow Springs, Stetson Creek and Harvest Park stream instability,water quality and street flooding.
developments. A single major drainageway, McClellands
Creek, conveys flow from the upper end of the basin to Recommended Solutions
the downstream discharge point along the Fossil Creek Flood Damage
Reservoir Inlet Ditch.The majority of the basin is either
developed,or is being developed,with residential and The recommended selected plan of improvements was
commercial land areas. developed to provide cost-effective solutions to mitigate the
drainage problems. Proposed projects:
• Modify the pond embankment along County Road 7;
(F • Construct a spillway through the Union Pacific 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
z ,
Oakridge Drive;and
• Modify the overflow channel at the Upper Whalers Cove
Detention Pond.
The total cost is$4.3 million and no benefit-to-cost ratio was
calculated since the proposed projects bring facilities up to
current drainage standards rather than reduce flood damage.
t„ 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.
23
City of Fort Collins Utilities
4 f d Town and flooded basements and first floors of many homes. In
1961, the local paper noted that a lake formed at College
About the Basin Avenue and Mulberry Street during a typical rainstorm.This
continues to be a problem today.
The Old Town Drainage Basin is located in north-central Fort
Collins.The basin has a drainage area of approximately 2,120 Additional noteworthy storms occurred in 1983, 1988, 1992 -
acres,including approximately 400 acres of the Colorado and 1997.The 1992 flood was centered in Old Town and,
State University campus.The entire basin is urbanized,with according to the CSU rain gauge, two and a half inches fell
some development occurring in the late 1800s. in only 30 minutes. Damage to homes and businesses totaled
$438,000 in 1992 dollars and nearly 50 property owners —
In general,the basin drains from west to east.The Old Town reported flooded basements.The 1997 Rood in Old Town
Basin receives some runoff water from the Canal Impor[a[ion occurred the same day as the notable Spring Creek flood.
Basin directly west of Old Town. Most of the water from Old Most attention was focused on Spring Creek, but there also
Town drains to the Poudre River,just to the east. was severe flooding and extensive damage in many parts of
Three major capital projects were completed in Old Town Old Town.
since the 1997 flood: the Howes Street Outfall,the Locust Significant progress has been made in recent years to help
Street Outfall and the Oak Street Outfall.These projects minimize damages. Still, it does not take much rain to
significantly reduced flooding problems in the basin,and cause significant flooding in the Old Town Basin, especially
they removed more than 700 properties from the mapped in basements.
floodplain. However, in general the projects did not reduce
flooding west of Mason Street and many properties remain Basin Problems
in the floodplain.
Basin flooding results primarily from encroachment and
The original master plan for this basin was completed in urbanization of natural drainage corridors, none of which _
1993. In 2002,the City of Fort Collins Utilities mapped a are visible today. Instead,the streets become stream channels.
revised floodplain for this area as part of a comprehensive When the streets and the undersized storm sewer system
update of the City's stormwater master plan. cannot contain the flow,water spills out of the street and
floods homes and businesses.
Flooding History
In the heart of Fort Collins, the Old THURSDAY FORT COLLINS —
Town Basin encompasses the Old + ^�25.1"2 COLORMOAN ,
Town business district and surrounding
neighborhoods. Some areas of Old Town JLike opening a faucet'
were established in the 1800s when little
thought was given to storm drainage.As Relentless hour of rain
a result, the basin has experienced many floods streets, buildings
h
floods throughout its history.
». 4.r.:.�..`
M„
Local newspapers have documented
numerous floods in Old Town. In 1904,
plugged storm sewer inlets caused a
lake to form on Walnut Street.Again in
1 storm r were v rwh Imed -
1 sto sewers e e o e e 95
when six inches of rain fell in 27 _
hours.A small river formed that flowed
east along Locust and Plum Streets This article appeared in the local paper following a 1992 flood in old Town.
Store) pater Master Plan Gtecwji c summon
1
A series of wetland-based water quality ponds in the Udall Natural Area was part of the oak Street
' outfall Stor mwater improvement Project completed in 2002.
The remapping of the floodplain identified several areas of
flood hazard within the basin. During a 100-year storm,
approximately 624 structures would be damaged and nearly
50 street intersections would be flooded.This would result
� i Ion
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; ?1;
• Myrtle Street Storm Sewer;and
• Mulberry Street I Riverside Avenue Storm Sewer.
The total cost is$50.4 million and the benefit-to-cost ratio
is 1.41. Once all improvements are in place, damage to The recently completed Locust Street outfall Project is one
350 structures will be eliminated in a 100-year storm, and of three large capital projects designed to reduce flooding
damage will be reduced for the remaining 274 structures. danger in the Old Town Basin.
' 25
City of Foil Collins Utilities _
Poudre River Flooding History —
About the Basin The location of the City of Fort Collins is where it is
today because of flooding on the Poudre River.The first
The Cache la Poudre River,a major tributary to the South military post, Camp Collins,was originally established
Platte River, is located in Latimer and Weld Counties, near the present day town of LaPorte. It was destroyed in
with a small portion of the drainage basin extending into 1864 when the Poudre River flooded. Camp Collins was
southern Wyoming. Passing through Fort Collins, the relocated to higher ground near present day Old Town in
Poudre River corridor provides for stormwater drainage Fort Collins.
from various contributing City drainage basins.
There are several well-documented large floods on the
Floodplain restrictions have limited the amount of building Poudre River around the turn of the century.A flood in
in the floodplain, resulting in lower development density. 1891 was due to a dam break on Chambers Lake.The
This lower density,combined with sensitivities to the most notable flood was in 1904.This storm was greater
natural environment, has resulted in a high concentration than a 100-year event and resulted in one death.The
of parks and open space along the river corridor. Portions of Buckingham,Alta Vista and Andersonville neighborhoods —'
the river corridor also contain old industrial sites, reflecting were severely damaged by the 1904 flood.
a time when the river was seen as a convenient means of
carrying off waste products. Numerous other floods have occurred on the Poudre River over time.The most recent flood on the Poudre River was a _
Many of the citys natural areas are located within the relatively small one in the spring of 1999. It was caused by
Poudre River corridor.The riparian ecosystem provides rain and snow runoff during a warm period in April.The
important habitat for a variety of wildlife and also contains flood lasted only a few days, but resulted in a great deal of
diverse vegetation that is both biologically and aesthetically bank erosion and threatened many properties. —
valuable.The biological diversity,along with the sheer
length of mostly undeveloped land,create a critical habitat
of regional significance. --
The Andersonville neighborhood was severely damaged when the
Poudre River flooded in 1904. Note the high water mark at the arrow.
Storrmvoter Muster Plop Executive.suminaor
Basin Problems
Approximately 3,160 acres of floodplain
between Taft Hill Road and I-25 would be
inundated by a 100-year flood, damaging
' approximately 188 structures. Estimates
indicate that damages to property, utilities
and infrastructure caused by the 100-
' year flood would total $9.5 million, with
expected annual damages of$460,000.
Additional damages would be expected due to
' significant erosion.
Riverbank conditions vary widely both
in terms of their ecological condition and q
structural stability. Some sections have stable ;
banks and a well-developed floodplain with
developing riparian zones. Other sections
have been stabilized but are not aesthetically pleasing and The poudre River in southeast Fort Collins.
' provide little wildlife benefit. Still other sections have
steep,eroding banks with concrete embankments and
little vegetation.
' Recommended Solutions
Multiple alternatives were evaluated for reducing or
eliminating flood damage and for controlling erosion.
Projects include:
' • improving structures such as levees or channels;
• floodproofing;
' • purchasing flood insurance; or
• acquiring property.
The final 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. Benefit-to-cost ratios vary from less than one to
over five,depending on the project. Once all improvements
' are in place, flood damage(up to a 100-year storm) to all
188 structures would be eliminated.
' 27
City of Fort Collins utilities
Spring Creek Spring Creek is a FEMA-designated floodplain and is subject
to the City's floodplain regulations.The new mapping also
About the Basin includes areas beyond the FEMA floodplain which are
considered to be in a City-designated floodplain.
Spring Creek is a major watercourse that flows from Spring
Canyon Dam at Horsetooth Reservoir to its confluence Flooding History
with the Poudre River.The Spring Creek Drainage Basin
encompasses nearly nine square miles in central Fort Usually an appealing stream adjacent to a popular bike trail,
Spring Creek can change into a torrent of floodwaters during
Collins.The basin is dominated by residential development
but it also includes open space,parks and isolated areas of severe storms.
commercial and industrial development. In 1938,when floodwater backed up to a width of 200 feet
On July 28, 1997, the city's worst natural disaster occurred behind a culvert at Stuart Street, it spilled over the top and
when Spring Creek flooded following 14.5 inches of took the road surface with it. In 1961, Prospect Road and
rainfall in 31 hours.The impact of the storm would have Hospital Road (Lemay Avenue)were flooded for the fourth
been far worse if the City had not invested more than time that summer,when stormwater overflowed a 30-inch _
$5 million in stormwater improvements in the basin in the storm sewer. Flooding occurred in 1977 and again in 1983,
early 1990s.These included improvements to channels and When a severe storm dropped 2.22 inches of rain in three
bridges, reinforcement of the Burlington Northern Railroad hours. Spring Creek backed up, filling the basement of a —
embankment, and acquisition and relocation of structures paint store and washing 10,000 gallons of painting chemicals
in high hazard areas (30 mobile homes,nine houses, one into the waterway.
business and one retirement home). The most devastating flood in the basin's history occurred
The original Spring Creek master plan was prepared in in 1997. The Coloradoan reported on "The storm that tore
1988.The City of Fort Collins Utilities revised the basin's city's hearts,homes,"when five residents lost their lives,a
floodplain as part of a comprehensive update of the City's building exploded,a train derailed and 400 people were
stormwater master plans in late 2002. rescued from the floodwaters.Across the city, over$200 _
million in damages were attributed to the storm.
Basin Problems
The master plan update identified 178 structures,
eight roads and the Burlington Northern Railroad that
i would be damaged during a 100-year storm with an
estimated$8.78 million in damages. If nothing is done
r" to mitigate this damage, it is estimated that$12.25
Wet+ie = ' million of damage would occur over the next 50 years.
1+ f 04
+v.
ti.
The high water mark indicates the level of flood waters on
spring Creek at Stuart street during the 1997 storm.
' Recommended Solutions The total cost is $11 million and the benefit-to-cost ratio is
1.49. Once all improvements are in place, damage to 154
Flood Damage structures will be eliminated in a 100-year storm,
The recommended plan of improvements was developed to 24 structures would be damaged.
provide cost-effective solutions to mitigate damages from Habitat Enhancement
the 100-year storm. Projects include:
The master plan also includes an assessment of the
• Constructing or expanding detention ponds: C&S creek's habitat quality and enhancement opportunities.
Railroad Detention Pond, Rolland Moore Park Enhancements include restoring banks with native
Detention,Taft Hill Detention Pond Expansion, vegetation, removing or modifying manmade barriers to
Southwest Regional Park Detention Pond and Dixon fish passage and restoring portions of the creek to a more
Creek Detention Pond; natural formation.
• 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.
1
may,
' During the 1997 flood on spring creek, overtopping of the railroad embankment caused a
multiple train car derailment and damage to the Burlington Northern Railroad tracks.
' 29
City of Fort Ccgirs UC4Iife� ,_„
West Vine The original master plan for the West Vine Basin was v
completed in 1980. In early 2003, the City,of Fort Collins
About the Basin Utilities and Latimer County mapped a new floodplain and
floodway for the basin as part of a comprehensive update of _
The West Vine Basin, located in northwest Fort Collins, the City's stormwater master plans.
extends east from Horsetooth Reservoir to the Cache la
Poudre River and south from West Vine Drive to Mulberry Flooding History —
Street and Laporte Avenue.The total area is approximately
2,350 acres.The eastern half of the basin is part of the Fort Development in the basin occurred sporadically over the
Collins Urban Growth Area and the western half,west of years,leaving some areas with small storm sewers while other
Overland Trail,includes open space and the Colorado State areas have no storm sewer system at all. Many houses in the
University Foothills Campus. Less than 15 percent of the basin lie within the floodplain and have suffered damage
basin is within city limits; the rest is in Latimer County. during even relatively small storms.
In general,the basin drains from west to east along five In 1992, Irish Drive was flooded by a storm centered over
flow paths that are not well-defined.Throughout the years, Old Town that dropped two and a half inches of rain in less --
development has occurred over the historical flow paths. than an hour. Snowplows were used to push water from Irish
Most of the basin's drainage facilities are inadequate during Drive into the irrigation canal. Again in 1994, a storm caused
any storm event,and as a result,drainage problems have water to overtop Overland Trail and flooded several homes.
occurred regularly. In thel997 flood, Spring Creek received the most damage,
The main channel of the West Vine drainage, downstream but considerable destruction also occurred in the West
of Laporte Avenue, is usually dry. Several locations lack a Vine Basin. Nearly 12 inches of rain fell in two days in the
well-defined channel because of development and because western portion of the basin.The large lake that formed on
stormwater is intercepted by irrigation canals. Only the Hollywood Street on July 28 inundated houses with three
reach upstream of Laporte Avenue and Poudre High School to four feet of water before it spilled onto Sunset Street and
has perennial flow in a well-defined channel.This reach is the Irish neighborhood. Damages resulting from this event _
known as Soldier Canyon Creek,and
typically there is a small amount of
base flow 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 Latimer
County Canal No. 2 (LC2)—impactthe 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.
Flooding in the Irish neighborhood in 1999.
3
Stornwpater piaster P,nn Executive sommor,
caused an outcry from hard-hit residents for drainage Recommended Solutions
improvements by the County. Homes in other parts of the
basin also were damaged by this storm. Flood Damage
A slow moving spring rain in 1999 caused significant The recommended plan of improvements was developed to
' flooding in the basin when over four inches of rain fell provide cost-effective solutions to mitigate damages from the
in a two day period on already rain-soaked ground.The 100-year storm. Proposed projects:
storm culminated in the second wettest April on record. . Construct five detention ponds west of Overland Trail and
' Floodwaters reached depths of 18 inches on Hollywood one east of Taft Hill Road (on the Forney property south
Street and triggered voluntary evacuations. East of this area, of Vine Drive);
on Irish Drive, City crews filled sandbags and pushed water
' into the New Mercer Irrigation Canal with snowplows and ' Construct a channel from the Poudre School District
heavy machinery. outfall at Impala Drive and Laporte Avenue, north to the
Irish outfall channel;
Basin Problems • Construct a channel from NMD and Cherry Street to
Three main areas in the West Vine Basin have a history Taft Hill Road,continuing east under Taft Hill, and LC2
' of flooding problems.They include the Irish Green to the West Vine Drive regional detention pond;
Subdivision, the subdivision at the northwest corner of Taft • Construct a channel as an outfall from the West Vine
Hill Road and Laporte Avenue,and the Second Filing of Drive regional detention pond to the Poudre River;
the Hanna Subdivision. Residents have indicated there has . Construct spill structures on the NMD and LC2; and
been stormwater up to their homes' foundation levels or
higher on a regular basis. Other reports indicate that the ' Install new flood warning gauge sites.
open field west of the Hanna Subdivision has experienced The total cost is $12.2 million and the benefit-to-cost ratio
ponding during long or intense storms. is 1.0. Once all improvements are in place,there will be two
' Other flooded areas include the Bonnaview and Rosteks structures damaged in a 100-year storm.
Subdivisions and the railroad embankment near Shields Excessive Erosion/Poor Stream Habitat
' Street and West Vine Drive. Flooding in the Bonnaview
Subdivision resulted from spilling from the PV&L.The The plan proposes channel improvements to improve habitat
abandoned railroad embankment near Shields and Vine was ratings, stream stability and water quality. Improvements
' overtopped downstream of the existing culvert. include grading to flatten out steep bank slopes, the creation
of pools and riffles and planting native vegetation.
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 Latimer 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.
1
' 31