Comb Wash is a valley in southeastern Utah, in San Juan County. It runs from Elk Ridge in the north approximately 35 miles (56 km) to the south, where it merges with the San Juan River at an elevation of about 4200 feet (1280 m). The eastern edge of the wash forms steep cliffs of Navajo Sandstone, rising in places to 1000 feet (300 m) above the valley floor.