West Fork San Gabriel River

The West Fork is one of two major streams, the other being the East Fork, that combine to form the San Gabriel River in Los Angeles County, California. The West Fork flows for 19 miles (31 km)[1] in an easterly direction from its origins at Red Box Gap, in the San Gabriel Mountains, eventually reaching San Gabriel Reservoir where it is bridged by SR 39 just above its mouth.

West Fork San Gabriel River
Location of the West Fork in California
Location
Country	United States
State	California
Physical characteristics
Source	Red Box Gap
• location	Angeles National Forest
• coordinates	34°15′29″N 118°06′13″W[1]
• elevation	4,530 ft (1,380 m)
Mouth	San Gabriel River
• location	San Gabriel Reservoir
• coordinates	34°14′23″N 117°51′24″W[1]
• elevation	1,473 ft (449 m)
Length	19 mi (31 km)[1]
Basin size	104 sq mi (270 km2)[2]
Discharge
• location	Camp Rincon, near the mouth[2]
• average	71 cu ft/s (2.0 m3/s)[2]
• minimum	1.7 cu ft/s (0.048 m3/s)
• maximum	34,000 cu ft/s (960 m3/s)

The major tributaries of the West Fork, from upstream to downstream, are Devil Creek, Bear Creek and the North Fork San Gabriel River. A large portion of the watershed is situated in the San Gabriel Wilderness, whose southern boundary is formed by the West Fork. Cogswell Dam impounds the river to create the 10,785-acre-foot (13,303,000 m³) Cogswell Reservoir, whose primary function is flood and silt control for the San Gabriel Valley.The West Fork of the San Gabriel River is a refuge for Southern California wild rainbow trout.[3]