Planning commission unanimously recommends approval of Halligan Reservoir expansion 10‑41 permit

The Larimer County Planning Commission voted Feb. 19 to recommend that the Board of County Commissioners approve a 10‑41 permit for the City of Fort Collins’ Halligan Reservoir expansion, a municipal water‑supply project that would replace the existing dam and enlarge storage on the North Fork of the Cache la Poudre River.

The recommendation passed on a roll call vote; all commissioners present voted yes. The commission recommended approval subject to the 53 conditions of approval recommended by county staff and an update to a time‑limit condition to align with language in the county land use code. The Board of County Commissioners will hold the final land‑use hearing on the project on March 24.

County planning manager Jenny Axmaker said staff found the application met the Larimer County Land Use Code criteria for a 10‑41 permit, subject to conditions. “Staff reviewed the submitted documentation, we reviewed the land use code criteria and found that the proposed Halligan Water Supply Project 10‑41 permit application satisfies all the applicable criteria … subject to the implementation of the conditions as approved and recommended by staff,” Axmaker said.

Why it matters: Fort Collins says the project will add storage capacity that the utility needs for municipal reliability and to reduce the frequency of drought restrictions for customers. The proposal also includes multiple mitigation measures the city and federal agencies identified during the project's long NEPA review, including fish passages, wetland mitigation credits, wildlife monitoring and an oxygenation system for the enlarged reservoir.

Project scope and timeline The City of Fort Collins, acting through Fort Collins Utilities, is the applicant and owner. The project would enlarge the existing Halligan Reservoir’s surface area from about 253 acres to about 391 acres and add roughly 8,200 acre‑feet of municipal storage on top of an existing 6,400 acre‑foot historical pool used by the Northern Poudre Irrigation Company (NPIC). Project plans call for construction of a new roller‑compacted concrete dam approximately 200 feet downstream of the existing structure, partial demolition of the old dam, reconstruction of the NPIC diversion (the North Poudre Canal diversion), construction of up to two fish passages (including at the Gateway Park intake on the main stem), and supporting access and operations infrastructure.

Nicole Poncelet Johnson, Fort Collins’ water executive director, described Halligan as “a key tool in the tool bucket of water supply in this region” and framed the work as replacement of an aging, century‑old dam and an increase in municipal storage for reliability.

Fort Collins project manager Darren Parkin summarized the schedule presented to the commission: federal NEPA work (record of decision) and other state and federal technical permits are still pending; the city expects to enter final design and technical review before construction. The presentation described construction phasing that would begin after completion of technical review, with major dam construction anticipated in a multi‑year window, and project completion currently estimated in the 2029–2030 timeframe.

Permits, conditions and outstanding approvals This application is a 10‑41 permit under the Larimer County Land Use Code; those local 10‑41 regulations implement state law allowing local review of matters of statewide concern such as large utility and reservoir projects. Axmaker said staff referred the application to 33 agencies and received 17 responses; no referral agency issued an outright objection, but reviewers asked for additional documentation and permits before construction can proceed.

The project has completed a federal environmental impact statement (EIS) in 2023 as part of the NEPA process. Outstanding items identified by staff and the applicant include Army Corps of Engineers permitting (including Section 404/401 wetlands and water quality matters) and other state and federal technical approvals. Staff recommended 53 conditions of approval to be implemented during the county’s subsequent technical review and permitting steps.

Key infrastructure and mitigation measures - Dam replacement: new dam about 200 feet downstream from the existing structure, roller‑compacted concrete with a larger spillway sized to current flood standards. - Hydrology/storage: proposed total new municipal storage of approximately 8,200 acre‑feet in addition to the existing NPIC pool (existing pool ~6,400 acre‑feet); surface area to increase from ~253 acres to ~391 acres. - Power and operations: removal of existing overhead power line; on‑site power proposed from a combination of micro‑hydro, solar, batteries and diesel generator backup for limited needs. - Construction features: temporary widening of roads, staging areas, concrete batching plant and a test quarry to evaluate on‑site aggregate for concrete; the test quarry and limited west‑access work would be of relatively short duration (applicant estimated months for test quarry work). - Fish and stream mitigation: replacement or reconstruction of the North Poudre Canal diversion and creation of up to two fish passages (Gateway Park passage intended to accommodate trout across a broad flow range; a second smaller passage at the NPIC diversion aimed at small native fish); operational ramping limits and a plan to bypass peak runoff days to reduce abrupt flow changes. - Flow commitments described by the applicant: protected mitigation releases proposed as part of the water‑court filings and operational plan, including a winter baseline release of about 3 cubic feet per second for seven months and a summer release of about 5 cfs routed to Seaman Reservoir (applicant said those releases are being protected in water court). The applicant also described releases through low‑level outlets to move sediment and support habitat goals. - Wetlands and habitat mitigation: the city described purchasing credits from a nearby mitigation bank (applicant cited a purchase on the order of $7,440,000 to secure required stream and wetland mitigation credits) and additional off‑site conservation to offset permanent impacts; the package also includes collaring and monitoring of a local bighorn‑sheep herd and other adaptive wildlife measures.

Applicant and agricultural coordination Fort Collins representatives told the commission the city will operate the reservoir and coordinate metering at the NPIC diversion so NPIC receives its historical deliveries. Eric Pianti, the city’s water attorney, said the utility has an existing program to rent excess water back into agricultural ditches in wet years and expects to continue coordination with irrigators. “The city has a long standing program to rent its excess water to local agriculture,” Pianti said.

Public comment and local concerns Two in‑person speakers addressed the commission. Rancher Zach Thode, who manages Roberts Ranch and owns property upstream, said he supports storage projects generally but asked for clearer coordination with landowners on recreation and trespass enforcement and better communication about access and future use. “In principle, I think any storage project in Larimer County is a good project, and I support any storage project, including the Halligan storage project,” Thode said, while also urging improved coordination.

Landowner Jordana Barrick urged stronger commitments on road maintenance, turn‑lane safety at Highway 287, and timely outreach to landowners. Barrick asked that the county ensure the applicant work with CDOT on the 287 turn lane and that road‑maintenance and dust/noise mitigation be enforced during construction.

Applicant responses and construction traffic Fort Collins staff told commissioners they plan to use the east access for most construction traffic and estimated peak daily construction traffic in full build‑out scenarios at roughly 70 vehicles per day on the east access and under 20 vehicles per day on the west access when on‑site aggregate is used. If off‑site aggregate is required, the applicant said truck traffic could rise (applicant said an off‑site scenario might reach higher daily truck counts identified in the project EIS). The city also said it would coordinate with the Phantom Canyon Ranches association and other landowners and would update its contact lists and outreach as part of the technical review.

Commission action and next steps Commissioner Connor Duffy moved the recommendation and the commission amended one time‑limit condition to match county land‑use code language before voting. The commission’s positive recommendation sends the matter to the Board of County Commissioners for final action; a county land‑use hearing on the 10‑41 permit is scheduled for March 24. Even with county approval, the applicant must complete outstanding state and federal permits (Army Corps 404/401, other state approvals) and satisfy the county’s technical review and the 53 conditions of approval before major construction begins.

Funding and scope notes Commission materials and the applicant’s presentation state the project has progressed through federal NEPA and other review steps across many years; the applicant said the final EIS was completed in 2023. The project includes both permanent and temporary impacts, and staff described the 53 recommended conditions as the mechanism to bridge the limited statutory review period for 10‑41 permits and the detailed technical review that follows.

The commission’s recommendation and the public record for this item are incorporated into the county’s March 24 land‑use hearing for a final decision by the Board of County Commissioners.