Project Overview

A New and Much-Needed Reservoir

As Northern Colorado’s growth continues, the region will need collaborative projects that not only help us meet its future water demands, but also protect the environment and wildlife, help maintain local food production, and preserve the region's quality of life.

Those are precisely the objectives of the Chimney Hollow Reservoir Project. This effort is a collaboration between nine municipalities, two water districts and a power provider, working together to build Chimney Hollow Reservoir.

The new reservoir will be located just west of Carter Lake in southern Larimer County, and will store 90,000 acre-feet of water when built - slightly smaller than neighboring Carter Lake (112,230 acre-feet). The project will provide a firm yield of 30,000 acre-feet annually.  

Recreation Opportunities, Protections for our Environment

In addition to water storage for future generations, the project will include various environmental and wildlife enhancement measures. It will also be part of Larimer County’s open space plan and offer recreation opportunities, such as wakeless boating, fishing, paddle-boarding and access to hiking trails.

Widespread Support

The project has been approved by the U. S. Bureau of Reclamation, U.S. Army Corps of Engineers, Grand County, Colorado Parks and Wildlife and endorsed by former Gov. John Hickenlooper. It also has support from several environmental groups such as Trout Unlimited. It also aligns with the objectives of the Colorado Water Plan, which identifies additional water storage among the measures needed to meet the state’s future demands.


After receiving final approval from the federal government in 2017, engineers are currently finalizing the project’s design. Construction is expected to start in 2020, with water being stored in the new reservoir by 2024.

Making the Most of our Local Water Supplies

This project will not take away water from agriculture or other users, but would utilize the water rights associated with the existing Windy Gap Project, which has been delivering water since 1985. Once built, Chimney Hollow Reservoir will provide the additional storage needed to make the Windy Gap Project a more reliable delivery system for the local residents who currently depend on it, as well as their children and grandchildren.

A Critical Element in Securing Future Water Supplies

Northern Colorado faces projected water shortfalls in the upcoming decades, but participants in the Chimney Hollow Reservoir Project are pursuing an all-of-the-above strategy to address this issue. They’re embracing conservation and reuse opportunities, among other efforts. But the Chimney Hollow Reservoir Project will be vital in helping these local communities meet the challenges ahead.