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Fossil Creek Reservoir/Duck Lake
Larimer County

Size: 1,800 acres

Elevation: ~5100 feet

Habitats: Primary - open water

Secondary - grassland, lowland riparian, rural/agriculture, shore/bank, wetlands

Ownership: Municipal Private (North Poudre Irrigation)

Land Use: Primary - water supply Secondary - nature and wildlife conservation, hunting/fishing, recreation/tourism, agriculture/livestock, research

IBA Criteria: 1, 3, 4, 5


Site description

Location: The Fossil Creek Reservoir/Duck Lake site is located just south of the City of Fort Collins, in north-central Colorado.

Vegetative/natural features: The reservoir is partly surrounded by a band of cottonwood trees. The west end of the reservoir adjoins an extensive cattail marsh, which extends into shallow wetlands. Duck Lake adjoins wetlands, primarily on the south end. The remaining areas of the site are cropland and grassland.

Ornithological Importance

Over 145 species of birds have been reported at the site, including over 20 species of waterfowl, over 25 species of shorebirds, 10 species of gulls and terns, and 9 species of wading birds.


Wintering species: Average # Maximum #
waterfowl   20,000

Breeding species: Average # Maximum #
Black-crowned Night Heron n/a  
Great Blue Heron 100 nests  
Virginia Rail 100 pairs  
Sora 50 pairs  

Research and educational activities:
Colorado State University students have utilized the site for MS and Ph.D. research.

Conservation/Management Issues

Threats: 1. pollution; 2. disturbance to birds and habitat from recreational use.

Potential threats: 1. development.

Efforts to address threats: The City of Fort Collins and Larimer County have developed a Resource Management Plan and an Inter-Governmental Agreement to guide the management and protection of this area. They are seeking to lease the surface water rights from North Poudre Irrigation Company. Several central management issues (e.g., permitting boating on the reservoir) have yet to be definitively settled. A water quality study will be conducted to determine the current level of pollution in the reservoir.


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