Pacoima Wash, 33 miles (53 km) long, is a major tributary of the Tujunga Wash, itself a tributary of the Los Angeles River, in the San Fernando Valley of Los Angeles County, California. The stream begins at Mount Gleason, 6,502 ft (1,982 m), in the western San Gabriel Mountains of the Angeles National Forest. The upper reaches, sometimes known as Pacoima Creek, flow through Pacoima Canyon as a rapid mountain stream. It then reaches the Pacoima Dam Reservoir in the western San Gabriel Mountains of the Angeles National Forest and proceeds south in a free-flowing stream alongside Pacoima Trail Road. Below the dam, it is generally known as the Pacoima Wash. From there, it joins several other unnamed streams that drain the nearby mountains, collecting at Lopez Dam. South of that dam, Pacoima Wa