Riffe Lake is a beautiful 23.5 mile manmade reservoir on the Cowlitz River. It was created in 1968 after the construction of Mossyrock Dam. Riffe Lake is open year-round, and so are we! Riffe Lake offers beautiful coves to relax and swim in, waterfalls, and several miles of hiking trails. She also offers pristine fishing for anyone who wants to throw in a line. Rainbow and cutthroat trout, brown bullheads, small mouth bass, and Chinook salmon are just a few that are swimming in her waters.