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Water Supply & Demand
Fort Collins Utilities drinking water comes from two sources:
- The Colorado-Big Thompson (C-BT) Project, which includes Horsetooth Reservoir
- The Cache la Poudre River basin, including the Michigan Ditch and Joe Wright Reservoir System
The Colorado-Big Thompson (C-BT) Project diverts water from the upper Colorado River and stores it in Lake Granby for later delivery to Carter Lake and Horsetooth Reservoir. The C-BT project is administered by Northern Water, who sets the quota each year that determines how much water is available per unit owned. This quota significantly affects the supply available in a given year. Fort Collins Utilities (Utilities) currently owns 18,855 C-BT units.
In an average year, Utilities acquires about 50 percent of its water needs through the C-BT Project and the other 50 percent through a combination of direct flow rights and converted agricultural rights on the Cache la Poudre River. The amount of usable water in the Poudre River in any given year is highly variable and dependent mainly upon snow-pack conditions in the 1,056 square mile drainage area above the canyon mouth. Roughly 80% of the water produced in the watershed flows during the peak snowmelt months of April through July.
The Michigan Ditch and Joe Wright Reservoir system located near Cameron Pass on Highway 14 diverts water from the Michigan River (part of the North Platte River Basin) across the divide into the Poudre River Basin and Joe Wright Reservoir. Joe Wright Reservoir includes about 7,100 acre-feet of active storage and is the only raw water storage facility owned by Utilities that is used in its treated water system. The reservoir is used primarily to regulate the annual Michigan Ditch flows and has limited capacity to provide drought protection for Utilities.
Utilities supplies water to approximately 75 percent of customers within the city limits. The remaining customers are serviced by surrounding water districts, including East Larimer County Water District and Fort Collins-Loveland Water District. The various service areas are mapped here.
Each year, Utilities typically:
- Delivers an average of around 24,000 acre-feet per year of treated water to customers
- Uses approximately 3,000 acre-feet of raw water to irrigate Fort Collins' parks, golf courses, cemetery, and other green belt areas
- Delivers about 4,500 acre-feet of other raw water obligations
Utilities owns water rights, which in most years, yield more than our current annual demands. Per the Water Supply & Demand Management Policy (PDF 91KB), Utilities maintains enough water supply to meet at least a 1-in-50 year drought event in the Poudre River basin while maintaining 20 percent of the annual demand in storage (storage reserve factor) to provide extra protection against emergency situations (i.e. pipeline failure) and droughts exceeding the design drought. Today, Utilities’ water supplies can meet an average annual treated water demand of approximately 32,000 acre-feet during a 1-in-50 year drought.
During more severe droughts, restrictions or other measures may be needed to reduce demands to match available supplies per the Water Supply Shortage Response Plan (PDF 95KB). Every year, the City encourages water conservation to make efficient use of a scarce and valuable resource. Learn more about how Utilities manages its current water supplies while planning for future demands in the Fort Collins Water Supply and Demand Management Policy Revision Report (PDF 5MB).