The San Gorgonio River is a 26.8 miles (43.1 km) river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 primarily flowing in western Riverside County

Riverside County, California

Riverside County is a county in the U.S. state of California. One of 58 California counties, it covers in the southern part of the state, and stretches from Orange County to the Colorado River, which forms the state border with Arizona. The county derives its name from the city of Riverside,...

, except for a small upstream portion in southwestern San Bernardino County

San Bernardino County, California

San Bernardino County is a county in the U.S. state of California. As of the 2010 census, the population was 2,035,210, up from 1,709,434 as of the 2000 census...

, in southern California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Geography

The river's headwaters are in the San Bernardino Mountains

San Bernardino Mountains

The San Bernardino Mountains are a short transverse mountain range north and east of San Bernardino in Southern California in the United States. The mountains run for approximately 60 miles east-west on the southern edge of the Mojave Desert in southwestern San Bernardino County, north of the...

, on the west sde of San Gorgonio Mountain

San Gorgonio Mountain

San Gorgonio Mountain, also known locally as Mount San Gorgonio, or Old Greyback, is the highest peak in Southern California at . It is in the San Bernardino Mountains, east of the city of San Bernardino and north-northeast of San Gorgonio Pass. It lies within the San Gorgonio Wilderness, part of...

. The river flows south and then east to its confluence

Confluence

Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...

 with the Whitewater River

Whitewater River (California)

The Whitewater River is a small permanent stream in western Riverside County, California, except for a small upstream portion in southwestern San Bernardino County. Its headwaters are in the San Bernardino Mountains and 'mouth'—terminus in the Colorado Desert...

 in the western Coachella Valley

Coachella Valley

Coachella Valley is a large valley landform in Southern California. The valley extends for approximately 45 miles in Riverside County southeast from the San Bernardino Mountains to the saltwater Salton Sea, the largest lake in California...

. It drains the land east of the San Gorgonio Pass

San Gorgonio Pass

The San Gorgonio Pass el. cuts between the San Bernardino Mountains on the north and the San Jacinto Mountains to the south. Like the Cajon Pass to the northwest, it was also created by the San Andreas Fault...

, while the South Fork of the Santa Ana River

Santa Ana River

The Santa Ana River is the largest river of Southern California in the United States. Its drainage basin spans four counties. It rises in the San Bernardino Mountains and flows past the cities of San Bernardino and Riverside, before cutting through the northern tip of the Santa Ana Mountains and...

drains the land west.

The river is intermittent, with significant flow only following winter storms and snowmelt in the spring.