Cow Mountain is a seven-mile ridge in northern California’s Mayacamas Mountains, east of Ukiah and west of Lakeport, now managed as a large public recreation area with non-motorized use in the north and off-highway vehicle routes in the south. Its name reflects a nineteenth-century history of longhorn cattle that once ranged widely here before disappearing by the 1870s. The ridge also marks a major watershed divide shaped by a massive landslide about 5,000 years ago that redirected Clear Lake’s drainage. With springs, meadows, forests, and important wildlife habitat, it remains significant for its blend of recreation, ecology, and erosion control affecting Clear Lake.