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Project Overview#
Halligan Reservoir is an existing reservoir on the North Fork of the Poudre River, 25 miles northwest of Fort Collins. If approved, the Halligan Water Supply Project will enlarge Halligan Reservoir by approximately 8,200 acre-feet.

Increases Reliability and Resiliency
- Provides a storage reserve for emergency water supply.
- Increases drought security.
- Improves water system reliability and flexibility.
- Meets future water demands of the Fort Collins Utilities' water service area.

Environmentally Responsible
- Uses an existing reservoir.
- Small in size (only 130 additional acres inundated).
- No pumping, pretreatment or added infrastructure is needed to use water.
- Improves conditions on the North Fork of the Poudre River.

Cost Effective
The project is currently the most cost-effective option to meet Fort Collins Utilities' water storage and supply needs. Other water sources could cost much more. We evaluate the cost-effectiveness of the project at each milestone, ensuring it is the best course of action for the cost.
The U.S. Army Corps of Engineers (Corps) released a draft Environmental Impact Statement (EIS) in November 2019. The Corps will develop a final EIS before making a permitting decision on if Halligan Reservoir can be expanded.
Updates#
Fish and Wildlife Mitigation and Enhancement Plan Released
On April 19, 2023, the City of Fort Collins submitted a proposed Fish and Wildlife Mitigation and Enhancement Plan to the Colorado Parks and Wildlife Commission. The commission will be considering and discussing the proposed plan at its regularly scheduled meetings in May and June this year.
2022 Year In Review
From state and federal permitting to design work and dam concepts–see what was accomplished in 2022.
Potential New Dam Concept Identified
Preliminary design efforts revealed that two viable dam concepts exist for enlarging Halligan Reservoir.
2021 Year in Review
From state and federal permitting to preliminary design work and dam concepts– see what was accomplished in 2021.
2020 Year in Review
From state and federal permitting to preliminary design work and stream gages – see what was accomplished in 2020.
City Council Quarterly Updates
Find the past and present City Council quarterly updates here.
Fish and Wildlife Mitigation and Enhancement Plan Released
On April 19, 2023, the City of Fort Collins submitted a proposed Fish and Wildlife Mitigation and Enhancement Plan to the Colorado Parks and Wildlife Commission. The commission will be considering and discussing the proposed plan at its regularly scheduled meetings in May and June this year.
2022 Year In Review
From state and federal permitting to design work and dam concepts–see what was accomplished in 2022.
Potential New Dam Concept Identified
Preliminary design efforts revealed that two viable dam concepts exist for enlarging Halligan Reservoir.
2021 Year in Review
From state and federal permitting to preliminary design work and dam concepts– see what was accomplished in 2021.
2020 Year in Review
From state and federal permitting to preliminary design work and stream gages – see what was accomplished in 2020.
City Council Quarterly Updates
Find the past and present City Council quarterly updates here.
Explore Halligan Reservoir#

Halligan Reservoir north shore.

Existing Halligan Dam.

Existing Halligan Dam and North Fork of the Poudre River looking south west.

North Fork of the Poudre River looking south downstream of Halligan Dam.

Halligan Reservoir in the spring.

Aerial view of Halligan Reservoir.

Halligan Reservoir and existing Halligan Dam.

North Fork of the Poudre River downstream of Halligan Dam, looking north.

Top of Halligan Dam looking south.

The Halligan Reservoir shoreline.

Halligan Reservoir inlet.