[1] In 1963 the United States Army Corps of Engineers built Cougar Dam on the river primarily to generate hydroelectricity and control flooding, and the reservoir formed behind the dam.

[1] The lake is also used for recreation, including boating, fishing, swimming, and waterskiing.

The United States Forest Service maintains three campgrounds—Cougar Crossing, Slide Creek, and Sunnyside—near the reservoir, with opportunities for hiking and picnicking as well as camping.

Other campgrounds in the general vicinity include French Pete and Delta.

Terwilliger Hot Springs is along Rider Creek just west of the lake.