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Halligan Water Supply Project Final Environmental Impact Statement Published

Released on Tuesday, October 24, 2023

Contact Information

  • Darren Parkin, Halligan Water Supply Project Manager, ,


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On Oct. 23, 2023, the U.S. Army Corps of Engineers (Corps) published a Notice of Availability for the Halligan Water Supply Project (Halligan Project) final Environmental Impact Statement (EIS) in the Federal Register. This action is a significant milestone for Fort Collins Utilities (Utilities) and the Halligan Project. The project will provide added space to store Utilities’ water rights, enabling a more robust, resilient, and reliable water supply for Utilities’ current and future customers.

The Halligan Project requires a permit under Section 404 of the Clean Water Act (404 Permit) and must comply with the National Environmental Policy Act (NEPA). The final EIS is part of the NEPA evaluation process and describes potential impacts from enlarging Halligan Reservoir (modified proposed action) and other water supply alternatives that the Corps considered. In 2025, the final EIS will be supplemented with a water quality certification under Section 401 of the Clean Water Act. Shortly thereafter, the Corps is expected to issue its 404 Permit and associated Record of Decision to conclude the federal permitting process. Once all permits and approvals are in place, and the dam design is complete, construction can begin at the Halligan Reservoir site.

Halligan Reservoir is located on the North Fork of the Cache la Poudre River (North Fork), about 25 miles northwest of Fort Collins. The modified proposed action involves expanding Halligan Reservoir by building a new dam immediately downstream of the current dam, which is more than 110 years old. This would provide about 8,200 acre-feet of additional water storage for Utilities in Halligan Reservoir. Local environmental benefits include restoring flows to the North Fork, improving aquatic habitat on the North Fork between Halligan and Milton Seaman Reservoirs, and providing improved fish passage on the North Fork and elsewhere. Overall, the project will provide measures that reduce, mitigate, or improve effects on wildlife, the environment, and neighboring residents.

Before releasing the final EIS, the Corps conducted an extensive draft EIS process, which included a public comment period. The final EIS addresses the comments the Corps received and concludes public input.

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