Windy Gap Firming Overview

The Windy Gap Firming Project would increase the reliability of, or "firm," the Windy Gap Project supply by making efficient use of its existing water rights. The firming project's key feature is a new reservoir called Chimney Hollow, which would be built to provide dedicated water storage for 13 municipal providers. 
 
The Windy Gap Project diverts Colorado River water and pumps it to Lake Granby. From there, Colorado-Big Thompson Project facilities transport the water to the East Slope for delivery to Northeastern Colorado cities and businesses.  

Project StatusThe firming project reached a major milestone when the Grand County Board of County Commissioners approved a 1041 permit and several related agreements in late 2012. 

The permit and agreements create a package that greatly exceeds the project's required mitigation by providing significant voluntary benefits, including improvements to the Colorado River, additional water supply for West Slope water providers, and long-term commitments to Grand Lake and the Colorado River.

The U.S. Bureau of Reclamation released the project's Final Environmental Impact Statement, which outlines mitigation for impacts, in 2011. Reclamation is expected to release a final decision in late 2014, when other required approvals are also anticipated.

With design and construction slated to take about five years, Chimney Hollow Reservoir could be operational by 2020.

The Need The Windy Gap Firming Project would benefit 10 cities, two water districts and a power provider. Northern Water's Municipal Subdistrict is coordinating the permitting process for these residential providers, who face a serious lack of water supply as the region continues to grow. Although participants continue to increase water conservation measures, conservation alone cannot meet projected demands. 

  Project Participants
Map shows the locations of the 13 participants in the Windy Gap Firming Project. 
Click map to view it. 
 
 

Site of proposed Chimney Hollow Reservoir
The site of the proposed Chimney Hollow Reservoir with
Carter Lake on the right. View the Chimney Hollow Reservoir map.

Dedicated Storage The firming project would meet a need recognized about 25 years ago by Windy Gap participants: a dedicated reservoir to store Windy Gap water.

Because of the project’s junior water rights, Windy Gap water cannot be diverted in years of low runoff. Conversely, during some wet periods storage space in Lake Granby is not available for Windy Gap water, which has a lower priority than C-BT Project water.
 
Chimney Hollow Reservoir would change the project’s reliable annual yield from zero acre feet of water to about 30,000 acre feet, improving the reliability of water deliveries to participating water providers and, ultimately, the water users they serve. 

Chimney Hollow Reservoir
The 90,000-acre-foot Chimney Hollow Reservoir would be located southwest of Loveland and just west of Carter Lake, which holds about 112,000 acre feet of water. 
 
The reservoir would be filled using Windy Gap’s original 1980 water rights decrees with appropriation dates of 1967, 1976 and 1980, and diversions would adhere to previously-agreed-upon limits.