Chimney Hollow Reservoir will ultimately be filled with water from an existing water right on the Colorado River.  

That water right, filed by the late Longmont Mayor Ralph Price in 1968, has been the centerpiece of the Windy Gap Project since 1985, when Windy Gap Reservoir, pump plant and pipelines were completed. In the decades since completion of the reservoir, the Windy Gap Project has been intermittently delivering water to participants on the Northern Front Range. 

Delivery of Windy Gap water is contingent on two factors: the availability of water in the Colorado River under the junior water right associated with the project, and the availability of storage space in Lake Granby for that water. Water from the Colorado-Big Thompson Project takes priority in the reservoir, meaning if there is any Windy Gap Project in the reservoir when the spillway is reached, it is Windy Gap Project Water that goes over the spillway. 

Chimney Hollow Reservoir will be dedicated to storing Windy Gap Project water, which is why the project is also called the Windy Gap Firming Project, in that it “firms” the otherwise intermittent yield of the project. 

In 2022, the Windy Gap Project has yielded about 40,000 acre-feet of water that is now being stored in Lake Granby. In the coming months, that water will be delivered to Windy Gap Project participants for their use.