Lake Cushman is a 4,010-acre (16.2 km2) lake and reservoir on the north fork of the Skokomish River in Mason County, Washington. The lake originally was a long narrow broadening of the Skokomish River formed in a glacial trough and dammed by a terminal moraine from the last ice age, during the Vashon stade.
The lake was expanded after construction of the Cushman Dam No. 1. The lake is maintained by this dam and provides electrical power to the Tacoma Power system.
As a popular retreat for hiking, fishing, boating and kayaking, Lake Cushman's shoreline is dotted with resorts and rental cabins. The lake is notable for its beautiful crystal clear blue water and the huge round rocks surrounding it, as well as thick stands of hemlock, fir and cedar trees.
Lake Cushman was named in honor of Orrington Cushman, who served as interpreter for Governor Isaac Stevens during the Treaty of Point Elliott negotiations with Puget Sound Indians in 1854.
There is also a town near Lake Cushman known as Lake Cushman, Washington, or simply Cushman, Washington. Still unincorporated, it is the fastest-growing community in Mason County.