The Chimney Hollow Reservoir Project involves the construction of a new reservoir to store water collected from the
Windy Gap Reservoir in
Grand County, Colorado. The reservoir, the major component of the Windy Gap Firming Project, a subdivision of Northern Water, will help store water otherwise lost in wet years due to the insufficient capacity of the Windy Gap Reservoir and other reservoirs on
Colorado's Western Slope. The reservoir will store water from existing water rights. Construction on the reservoir's two dams (one on the north end and one on the south end) began in 2021, and water will begin flowing into it in 2025. Located just west of
Carter Lake in southern Larmier County, the new reservoir will hold of water, which will be used for municipal water supply for nine municipalities and three water districts on Colorado's
Front Range. The $690 million project is the first major dam to be built in Colorado in twenty years. The larger of the two dams will be over high. The reservoir's surface area will be . ==Municipal Subdistrict==