The East Branch South Fork Eel River, a tributary of the South Fork Eel River

South Fork Eel River

The South Fork Eel River is the longest and largest tributary of the Eel River, in the north-central part of the U.S. state of California. The river flows north from Laytonville to Dyerville/Founders' Grove where it joins the Eel River on the left bank...

, is formed by the confluence of Cruso Cabir Creek and Elkhorn Creek, in Mendocino County in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of 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 river is roughly 25 miles (40.2 km) long, meandering west to its confluence with the South Fork Eel at Benbow Lake State Recreation Area

Benbow Lake State Recreation Area

Benbow Lake State Recreation Area is a state park unit of California, USA, established around a reservoir on the South Fork Eel River. It is located in Humboldt County south of Garberville on U.S. Route 101....

. Major tributaries of the East Branch include Buck Mountain Creek, Squaw Creek, Rays Creek, and Tom Long Creek. The river flows west, turns north, and flows west again, through rugged terrain in the Coast Range of California. The East Branch is the South Fork Eel's largest tributary.