Mary’s Lake

Mary’s Lake is located in an enlarged natural basin several miles south of downtown Estes Park, CO. It is part of the Colorado-Big Thompson Project power system, which contains seven hydroelectric power plants.

Mary's Lake serves two primary purposes. It acts as an afterbay for the Mary's Lake Power Plant, and it also helps regulate C-BT Project water on its way to the Estes Power Plant.

Mary's Lake
Mary's Lake

Mary's Lake Power Plant When water exits the Adams Tunnel's East Portal, it drops 205 feet through a large pipe, or penstock, to the Mary’s Lake Power Plant. The Prospect Mountain Conduit and Tunnel carries water from Mary's Lake to the Estes Power Plant penstock.

Mary’s Lake has a capacity of 927 acre-feet, 1 mile of shoreline, 42 surface acres and a maximum depth of 33 feet. Mary’s Lake and its dikes cost $410,000 to build.

One Campground at Mary’s Lake
Mary's Lake sits just outside the boundaries of Rocky Mountain National Park and the Roosevelt National Forest. The lake has one campground on its shores. See the C-BT Recreation - East Slope page for more information.