The Walker River is formed in southern Lyon County, south of Yerington, by the confluence of the East Walker and West Walker rivers. The West Walker River originates at Tower Lake in Mono County, California, above sea level in the Stanislaus National Forest. It flows north through a rugged canyon which provides the route for U.S. Route 395. It then emerges into Antelope Valley, where some water is diverted to the Topaz Lake reservoir, enters Nevada in Douglas County and turns northeast. It flows through Hoye Canyon into Lyon County, then across the Smith Valley, past Smith, and finally through Wilson Canyon into the Mason Valley where it joins the East Walker.