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Halligan Water Supply Project

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 Halligan and NISP

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The Project

What is the proposed Halligan Water Supply Project?

The Halligan Water Supply Project, expected to be completed around 2026, will raise the height of the existing dam by 25 feet and increase Halligan Reservoir’s water storage by approximately 8,100 acre-feet. The project will meet demand of future Fort Collins Utilities water customers and provide increased reliability for existing customers to help protect against service interruptions related to prolonged drought and emergencies. 

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Where is Halligan Reservoir located?

Halligan Reservoir is located on the North Fork of the Poudre River about 25 miles northwest of Fort Collins, near Livermore, in the foothills above Cherokee Park.

Is enlarging Halligan Reservoir necessary for Fort Collins?

Yes. Without additional storage, Fort Collins is vulnerable to future interruptions in water availability and delivery. Current supplies are not enough to meet the needs associated with projected growth within the Fort Collins Utilities established service area, particularly in times of emergency and prolonged drought, along with the uncertainties associated with climate change.

Future generations need a reliable and secure water source that can withstand fires, floods, landslides and infrastructure failures.

The City of Fort Collins owns the right to water that it currently can’t store. Expanding Halligan Reservoir will allow the City to store water and provide additional flows to the North Fork of the Poudre River (restoring the often-disconnected habitat), and provide flexibility and reliability with our water supplies.

Careful planning and analysis have determined that enlarging Halligan is the most cost-effective and environmentally-friendly solution to providing for these future needs.

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Why are we only raising the dam 25 feet? Why are we not raising it more?

The proposed size of Halligan Reservoir is determined by a 50-year planning horizon to avoid creating larger-than-necessary reservoirs and limit environmental impacts. Over the last century, there have been several plans to enlarge Halligan Reservoir. Those initial plans called for a larger expansion of the reservoir, but with an increase in conservation efforts and partners who have withdrawn from the project, the amount of water needed has decreased.

Will the water from Halligan Reservoir be treated and used as the City's drinking water?

No.  After the City receives a permit to enlarge Halligan Reservoir, Fort Collins Utilities will be able to use the additional water stored in Halligan through water right exchanges.

Right now, Fort Collins Utilities does not own or use any water from Halligan Reservoir. The water currently in the reservoir is owned and controlled by North Poudre Irrigation Company.

Once enlarged, the City's portion of the water will be released from Halligan Reservoir and flow approximately 24 miles down the North Fork of the Poudre River to the confluence with the mainstem of Poudre River. The intake for Fort Collins Utilities’ water treatment pipeline is located near Gateway Park on the Poudre River, about a quarter-mile upstream of the confluence with the North Fork, meaning the water from Halligan cannot reach Utilities water treatment facility without additional infrastructure or pumping.

Instead of building new infrastructure, Fort Collins Utilities will take the same amount of water that's released from Halligan Reservoir at its pipeline above the confluence and leave the Halligan Reservoir releases to flow downstream for other users as a water right exchange.

Currently, about 65 percent of the water used by Fort Collins Utilities and its customers returns to the Poudre River at the City’s water reclamation facilities.

What if we do nothing?

Without the Halligan Water Supply Project, Fort Collins Utilities service area will be vulnerable to lack of water availability during emergencies.

Our region's semi-arid climate means the amount of water available from month-to-month and year to-year varies, especially during dry years and drought. Without additional storage, Fort Collins Utilities will be unprepared for prolonged droughts and water supply emergencies. As a result, more frequent and severe water restrictions could be likely. 

What other water supply alternatives being considered?

Many alternatives to the Halligan Reservoir enlargement have been evaluated over the last decade, including: 

  • Enlargement of the proposed Glade Reservoir (if constructed as part of the Northern Integrated Supply Project (NISP))
  • The acquisition of other existing agricultural reservoirs near Wellington
  • Expansion and/or development of new gravel pit reservoirs along the Poudre River

These alternatives, including a no-action alternative, are detailed in the draft EIS.

The alternatives studied to date are likely to provide a less certain water supply, raise various legal issues and be more expensive and/or less sustainable. 

The U.S. Army Corps of Engineers (Corps) will select one alternative to issue a permit, which might not be the Halligan Reservoir enlargement.

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Who will benefit from the project?

Fort Collins Utilities’ water customers will benefit from having a more reliable water supply.

Landowners and the Nature Conservancy surrounding the North Fork of the Poudre River will benefit from additional year-round water flow in the river.

Once the reservoir is complete, it will likely be open for limited recreation opportunities.

How large will Halligan Reservoir be if completed?

Currently, Halligan Reservoir is 253 acres (surface area) and 6,400 acre-feet (volume). The expanded Halligan Reservoir will about 386 acres or 0.6 square miles and 8,1000 acre-feet at full capacity. For comparison, the water from Horsetooth Reservoir could fill up to 10 enlarged Halligan Reservoirs. Expanded Halligan will be about 50 percent larger than it is now. 

When will the reservoir be expanded?

Water supply projects in the United States can take decades, from the beginning of permitting to the end of construction.

Fort Collins began the permitting process in 2006, and the reservoir cannot be enlarged until all permits are obtained. Permits are issued by the U.S. Army Corps of Engineers (Corps) and other federal, state and local agencies. The length of time needed to obtain all permits is uncertain and driven by the permitting agencies. Learn more about the permitting process.

Once a permit is issued, the schedule for design and construction of the project will be more certain. Design and construction of the project will take several years. Fort Collins Utilities hopes to begin constructing the project in 2024, with enlarged Halligan operations by 2026.

View Timeline

What is the difference between the Halligan Water Supply Project and other waters supply projects in the area, like the Northern Integrated Supply Project (NISP)?

The Halligan Water Supply Project and the Northern Integrated Supply Project (NISP) are two separate water supply projects. The Halligan Water Supply Project is proposed by the City of Fort Collins and includes expanding an existing reservoir near Livermore on the North Fork of the Poudre River. NISP is sponsored by Northern Water on behalf of 15 northern Front Range water providers, including 11 communities and four water districts, some of which surround Fort Collins Utilities' water service area. NISP includes Glade Reservoir, which is often confused with Halligan because it also is located near Livermore.


Comparison of Northern Colorado water projects: 

Project Name  Halligan Water Supply Project  Northern Integrated Supply Project (NISP)  Seaman Water Supply Project  Moffat Collection System Project  Windy Gap Firming Project 
Reservoir Name(s)  Halligan Reservoir (existing)  Glade and Galeton reservoirs (new)  Seaman Reservoir (existing Gross Reservoir (existing)  Chimney Hollow Reservoir (new) 
Current Reservoir Size (Volume & Area)  Vol: 6,400 acre-feet 
Area: 253 acres 
N/A  Vol: 5,000 acre-feet  Vol42,000 acre-feet 
Area: 418 acres 

Proposed Reservoir Size (Volume & Area) 

Vol: 14,500 acre-feet 
Area: 386 acres 

Vol: 170,000 acre-feet 
Area: 16,000 acres  

Vol: 45,600 acre-feet 
Area: 2,000 acres 

Vol: 88,000 acre-feet  Vol: 119,000 acre-feet 
Area: 842 acres 
Vol: 90,000 acre-feet 
Area:740 acres 

Firm Yield 

The estimated maximum amount of water that can be supplied by a reservoir under specified conditions.

8,000 acre-feet (for Fort Collins Utilities only, not including NPIC's existing portion)

40,000 acre-feet

Unknown 14,000 acre-feet 30,000 acre-feet
Location  Near Livermore 

Glade: Near Livermore 

Galeton: Near Greeley 

Near Gateway Park up the Poudre River Canyon  Near Boulder  West of Loveland 
Project Owner  City of Fort Collins  Northern Water  City of Greeley  Denver Water  Northern Water 
Who does the water serve?  Fort Collins Utilities service area  Erie, Left Hand Water District, Fort Morgan, Central Weld County Water District, Windsor, Fort Collins Loveland Water District, Frederick, Severance, Lafayette, Evans, Firestone, Eaton, Morgan County Quality Water District, Dacono  City of Greeley Water Customers Denver Water Customers  Broomfield, Greeley, Longmont, Loveland, Erie, Fort Lupton, Lafayette, Louisville, Superior, Platte River Power Authority, Central Weld County Water District, Little Thompson Water District 
  • Future emergency and uncertainty
  • Water storage and delivery flexibility
  • Water supply for future population
Water supply for future population  Additional municipal and industrial water supplies  Bolster and increase water supply to meet existing and future needs  Supply reliable water for future generations 
Project Status  Permitting  Awaiting permit decision   Permitting  Permitted  Permitted
Federal Permit Date  2022 (anticipated)  2019 (anticipated)  Unknown  2017  2017 
Anticipated Construction Start  2024

Glade: 2021 

Galeton: 2024 




Estimated Total Project Cost 






Unit per acre-foot cost of firm yield 






NOTE: Some of these projects are large scale projects that include reservoirs and other components beyond the reservoir mentioned in the table.  

Map of Northern Colorado water supply projects and key details

Click image to enlarge.

Why doesn't Fort Collins partner with Northern Water to obtain water from Glade Reservoir (NISP)?

Enlarging Glade Reservoir to include enough water to meet Fort Collins’ demand is one of the alternatives being considered in the Environmental Impact Statement (EIS) by the U.S. Army Corps of Engineers. However, due to the considerably larger footprint of impact, long-term operational costs and the associated greenhouse gas emissions due to pumping, Halligan is the City’s proposed alternative.

It is proposed alternative because the project enlarges an existing reservoir and therefore has fewer environmental impacts, less long-term operational requirements, doesn’t require pumping, emitting no greenhouse gases, rehabilitates a dam that will need to be repaired in the future, and is less expensive per acre-foot of water than NISP.

Will there be recreation options on Halligan?

The City of Fort Collins is considering opening Halligan Reservoir to limited recreation. Fishing with human-propelled boating may be allowed on the reservoir once enlarged. Access would be through Cherokee Park State Wildlife Area, which is open to high-clearance 4WD vehicles May-August. The rest of the year would be limited to walk-in access from Cherokee Park Road. 

The Process

Who decides if the reservoir will be expanded?

Halligan Reservoir cannot be expanded until all permits are obtained. The ultimate decision on whether Halligan Reservoir can be expanded is the responsibility of the federal agency that has been declared the lead agency on the project – in this case, the U.S. Army Corps of Engineers (Corps).

Throughout the permitting process, the Corps works with other federal, state and local agencies to evaluate multiple water storage alternatives and the impacts of each alternative on the environment and community. These data are collected and compiled in a draft Environmental Impact Statement (EIS). The public can provide their input until Jan. 26, 2020. Based on results from this permitting process, the Corps will select which water storage alternative to issue a permit, which might not be the Halligan Reservoir enlargement.

Following a permit from the Corps, the project requires permits from other federal agencies, the State of Colorado and Larimer County.

How are other federal, state and local agencies involved in the permitting of this project?

Many different agencies are involved in this project, and their level of involvement depends on how they are related to the project. Some agencies are landowners around the project, such as the Bureau of Land Management and Colorado Parks and Wildlife. Others require a separate study or permit prior to construction, such as Larimer County and Colorado Department of Health and Environment. These agencies are known as "cooperating agencies" with the U.S. Army Corps of Engineers (Corps) throughout the permitting process.

All cooperating agencies will provide written comments on the Environmental Impact Statement (EIS). For those agencies where a separate study or permit is required prior to construction, those permits will be pursued at the same time as the Corps’ permitting process.

How long will the permitting process take?

Fort Collins Utilities entered the federal permitting process in 2006 and hopes to receive a final permit decision in 2022. The permitting schedule is dictated by the U.S. Army Corps of Engineers (Corps) and other permitting agencies. The City of Fort Collins has very little control over how long the process takes. Other water supply projects have taken decades to complete, from the beginning of permitting through construction. 

Project Began Permitting Status
Windy Gap Firming Project 2003 Record of decision 2014
Gross Reservoir Expansion 2003 Record of decision 2017
Northern Integrated Supply Project (NISP) 2004 Final EIS released 2018
Seaman Water Supply Project 2006 Draft EIS expected 2020
Halligan Water Supply Project 2006 Draft EIS released Nov. 2019
Why is the project taking so long?

The City of Fort Collins entered the permitting process with the U.S. Army Corps of Engineers (Corps) in 2006. The federal environmental permitting process consists of thorough analyses of project needs, impacts and ways to mitigate those impacts, and that takes time.

Initially, the City partnered with the Tri-Districts and North Poudre Irrigation Company (NPIC) on the Halligan Water Supply Project. At that time, the proposed reservoir was more than four times larger than what is being proposed today. Slowly those partners withdrew from the project due to the long schedule and cost of the permitting process. 

Other early decisions on the permitting side resulted in an extended permitting timeframe. Initially, the impacts of Halligan Reservoir were evaluated in conjunction with two other local water supply projects in the Poudre River watershed – Glade Reservoir (part of NISP) and Milton Seaman Reservoir, downstream of Halligan. This approach made sense from a perspective of regional impacts but delayed an already long and costly permitting process.

All these items above are outside of the City of Fort Collins’ control. We have carefully monitored cost and progress on this project since 2006, and have reached a major milestone in the permitting process with the release of the draft Environmental Impact Statement (EIS) Nov. 22, 2019. 

Project History

The Cost

Who is paying for the project?

The Halligan Water Supply Project will be funded primarily from the Utilities’ Water Supply Requirements (WSR) with a small amount (less than 15%, assuming a $120M cost) funded by the Excess Water Use Surcharge (EWUS) and monthly customer usage charges (rates).

The WSR is a dedication of water rights or cash-in-lieu (CIL) of water rights by new and redevelopment to ensure that adequate water supply and associated infrastructure are available to serve the development’s water needs. The EWUS is tied to the WSR CIL rate and is charged for use of surplus water supplies by existing customers beyond what was provided at the time of development. Both fees are adjusted biennially and are generally based on the total cost of water supply needs identified in Utilities’ Capital Improvement Plan.

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Do the benefits outweigh the cost?

Yes! Without increased water storage, such as an enlarged Halligan Reservoir, existing and future Fort Collins Utilities customers will be vulnerable to interruptions in water service during situations such as prolonged drought or emergencies like forest fires or infrastructure failures.

The cost of water continues to rise in Northern Colorado, but the Halligan Water Supply Project remains the most cost-effective alternative to meet the demand of future Utilities water customers and provide increased reliability for existing customers. Other water supplies and water storage projects in Colorado cost significantly more when compared on a unit-cost basis.

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Why is the cost presented as a range?

Based on information known at this time, current estimates indicate a probable cost of $120 million. However, costs could vary between $100 million to $150 million, depending on the final design and schedule of the project.

Several cost estimates have been developed for the project since 2006. Each update reflects new information gained and an increased understanding of the cost of permitting requirements; real estate acquisition; evolving best practices in dam design and construction; and unknowns that still exist given the conceptual nature of the project.

In the past, the cost estimate was presented as one value – a best estimate of total project costs. In the future, the total project cost will be presented as a range of probable costs, to better represent the evolving nature of the project and the unknowns that remain. This range accounts for uncertainties that still exist, such as possible permitting and schedule delays, mitigation requirements, environmental enhancement opportunities and other items that will affect the total cost of the project but are not currently known.

Total project costs will continue to be refined as permitting and design processes progress and project risks and uncertainties are further evaluated and mitigated.

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Why does the cost continue to increase?

The Halligan Water Supply Project entered the federal permitting process in 2006. Since then, several cost updates have been conducted. Each update has been a best estimate of total project costs at that time.

As we progress further into the permitting and design process, permitting agencies have required additional environmental studies, and we developed more mitigation strategies and opportunities for environmental enhancement. Concurrently, best practices in dam design and construction have evolved. All these items, as well as project delays, impact total project costs.

Fort Collins Utilities has limited control over the permitting process and schedule, both of which are significant cost drivers and dictated by the permitting agencies. As an example, each year that construction is delayed causes a $4 million increase due to cost escalation alone.

There are also several unknowns given the conceptual nature of the project at this time. The latest cost estimate accounts for these identified and unidentified risks that will be mitigated or eliminated as the project progresses, allowing us to narrow down on a final cost.

In general, the cost of water continues to rise in Northern Colorado, and even with the updated cost estimate, the Halligan Water Supply Project remains the most cost-effective alternative to meet the demand of future Utilities water customers and provide increased reliability for existing customers. Without the expansion of Halligan Reservoir, customers could be vulnerable to future service interruptions during prolonged drought and emergency situations.

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The Environment

Why can’t we just conserve water and avoid this project?

Fort Collins is using a smart, multi-faceted approach to water supply through conservation and future planning.

Water conservation is extremely important. Our customers are encouraged to conserve water by creating water-wise landscapes and replacing appliances and fixtures with high-efficiency models, among other strategies.

Fort Collins residents have risen to the challenge and have reduced per-person water use by 33 percent since 2000. In 2017, all of our customers used less water than in 1985. Quite an accomplishment considering the Fort Collins Utilities service area population has increased by more than 50 percent since then.

Even with outstanding conservation efforts, Fort Collins Utilities' customers are vulnerable to future uncertainties that could compromise our water supply, and conservation alone doesn’t replace the need for the Halligan Water Supply Project.

This project will provide added protection for our customers from future uncertainties and emergencies that can impact our water supply – prolonged drought, fires, floods, landslides and infrastructure failures, as well as uncertainty around climate change. These events could compromise our water supply even with increased conservation and water restrictions.

Water conservation helps ensure wise use of available water, especially during dry, hot summer months when little moisture is available naturally. In recent dry years, this conservation has allowed the City of Fort Collins to keep more water in storage for the coming years and not have water restrictions. Although conservation helps keep water in storage, our total storage capacity is limited by our existing infrastructure, and all the water we conserve cannot be carried over from year to year.

At this time, we have more water rights than we have the ability to store, so most of the water conserved by our customers passes to downstream communities. With the Halligan Water Supply Project, some water can be provided to the river for habitat improvement while water is retained for future water needs. 

Learn more about the City of Fort Collins’ conservation efforts and what you can do to help.

How will enlarging the reservoir impact the environment?

The City of Fort Collins has a strong stewardship ethic that provides the foundation for the management of current and future water use in the Poudre Basin.

While all water supply projects have impacts, the best projects include environmental benefits that outweigh the impacts. Our focus on stewardship has guided decisions related to the Halligan Water Supply Project and has gained the project recognition as an “acceptable planned project” by Western Resource Advocates.

All environmental impacts associated with the project, positive and negative, are thoroughly evaluated through the federal permitting process. Impacts are further evaluated through the state and county permitting processes. Appropriate avoidance and mitigation of negative impacts will be required before permits are issued. The environmental impacts are disclosed in a draft Environmental Impact Statement (EIS).

The Halligan Water Supply Project is smaller in scale and will make every effort to minimize environmental impacts, primarily through enlargement of an existing reservoir and dam rather than constructing a new one.

Additionally, the City of Fort Collins has committed to improved reservoir operations that provide minimum flows to the North Fork of the Poudre River year-round. Currently, the river often runs dry at various times throughout the year, which stresses fish and other wildlife. The minimum flows planned after the reservoir expansion will reconnect habitat that is currently segmented downstream of the reservoir.

Most of the negative environmental impacts will occur along the existing Halligan shoreline and upstream of the reservoir along a ¾-mile stretch of the North Fork of the Poudre River. These areas will be newly inundated from the reservoir expansion. Other negative impacts will be temporary and related to construction.

Each impact has been thoroughly evaluated and will be described in the draft EIS. The City of Fort Collins is currently developing conceptual measures proposed to mitigate the adverse impacts of the project, which will be summarized in the Conceptual Mitigation Plan that will be released for public review and comment with the draft EIS.

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How will storing more water in Halligan affect flows in the Poudre River?

There will be minimal negative impacts to both the Cache la Poudre River and the North Fork of the Poudre River. Currently, portions of the North Fork run dry in the summer and winter due to existing reservoir and diversion operations. The Halligan Water Supply Project will provide minimum flows to the North Fork year-round, which will reconnect the disconnected river, creating better habitat for fishery and wildlife.

The North Fork and Poudre River upstream of Laporte will see slightly (5-10%) decreased flows downstream of Halligan during run-off season (typically May-June). Flows through Fort Collins will see little, if any, decrease. 

What is being done to protect wildlife and natural habitat in the area?

The North Fork of the Poudre River runs dry for periods throughout the year.


The Halligan Project has been developed to balance water supply needs and avoiding and minimizing impacts to the environment. The project includes many improvements to the environment, such as re-establishing minimum flows and other enhancements to the North Fork, a river that currently runs dry in certain areas between Halligan and Seaman reservoirs much of the irrigation season.

However, several impacts still remain that will need to be mitigated. These include inundation of wetland areas and Prebles’ Jumping Mouse habitat, inundation of ¾-mile of the North Fork upstream of Halligan, and temporary construction impacts.

The City of Fort Collins is currently developing a Conceptual Mitigation Plan that will summarize the mitigation concepts and address any negative impacts resulting from the project. The Conceptual Mitigation Plan is intended to be conceptual in nature. Mitigation plans will evolve as the federal permitting process progresses. 

The overarching approach to mitigation for the Halligan Project is to:

  • Avoid and minimize impacts to the natural system to preserve ecological integrity.
  • Avoid and minimize impacts to social and cultural resources.
  • Compensate for unavoidable impacts through targeted mitigation measures that restore or replace locally significant resources and function.
  • Improve ecological function of the North Fork system as a whole.

Monitoring of the success of mitigation will be conducted for several years following construction and will be modified if not succeeding as planned.

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What mitigation will be provided?

Three-step mitigation process.


The City of Fort Collins is developing concepts to mitigate impacts from enlarging Halligan Reservoir, as well as enhance the current conditions in the area around the reservoir. The City plans to present these conceptual plans in a Conceptual Mitigation Plan that will be released and available for public review at the same time as the draft Environmental Impact Statement (released by the U.S. Army Corps of Engineers).

The first step in mitigation is designing a project that avoids impacts. This is achieved for the Halligan Water Supply Project by using existing infrastructure and minimizing the area of the reservoir.

The next step in mitigation is minimizing impacts. For example, the Halligan Water Supply Project includes operational measures to increase flows downstream and improve habitat along the North Fork of the Poudre River.

The final step in mitigation is compensating for unavoidable impacts. An example of this is replacing lost habitat function in wetland and riparian areas in the same watershed.  

These mitigation measures are still conceptual in nature and subject to input from the public and reviewing agencies. Some example measures that will be included in the Conceptual Mitigation Plan are:

  • North Fork Habitat Improvement
  • Inundated Wetlands and Riparian Resources 
  • Fish Habitat Improvement
  • Cultural and Paleontological Resources 
  • Wildlife and Special Status Species 
  • Water Quality
  • Air Quality
  • Other Construction Impacts
  • Public Recreation

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How does expanding Halligan Reservoir fit into the Colorado Water Plan?

The Colorado Water Conservation Board released the Colorado Water Plan in 2015. The plan identifies the need for more water for Colorado’s growing population and calls for increased water conservation, additional reservoir storage, temporary water transfer alternatives with farms and making full use of the water available to Colorado through its contracts with neighboring states.

Increasing storage in Halligan Reservoir makes use of an existing reservoir, which is less impactful on the environment than building a new reservoir and is more cost-effective than other alternatives considered.