The Trinity River begins deep in the Scott Mountains, in Trinity County, at the confluence of High Camp Creek and Chilcoot Creek. It flows south through a deep valley between the Trinity Mountains to the east and the Salmon Mountains/Trinity Alps to the west, picking up Coffee Creek, before entering Trinity Lake, a large reservoir created by the Trinity Dam. The East Fork and Stuart Fork of the Trinity River also flow into the reservoir. Just below Trinity Dam is the smaller Lewiston Dam, which diverts part of the Trinity River through a hydroelectric plant to the Sacramento River Basin as part of the Central Valley Project, providing irrigation water to California's Central Valley.