Riffe Lake is a large reservoir formed by the Mossyrock Dam over the Cowlitz River. It is one of the most popular fishing spots in the southwestern part of the state. There is very little development aside from a few parks and an agricultural area on the west end, but the hills surrounding the lake have been subject to clear-cutting. There are developed campgrounds at Mossyrock Park on the west end and Taidnapam Park on the east end. One particularly interesting spot is the Cowlitz River arm at the east end where the reservoir is channeled into a narrow, steep-walled valley.