Clear Lake is a mountain lake 86 mi northeast of Eugene, Oregon, United States in Linn County. It has two main bodies connected by a bottleneck. The lake is primarily fed by snow runoff from nearby Mount Washington and the surrounding areas. The runoff filters through underground caverns for more than 20 years before emptying into Clear Lake. The lake is also fed by two small creeks which may dry up seasonally. Clear Lake is the headwaters of the McKenzie River, which is the sole source of drinking water for Eugene.