The East Fork is the largest headwater of the San Gabriel River in Los Angeles County, California, United States.

It originates at the crest of the San Gabriel Mountains in the Angeles National Forest, at the confluence of the Prairie Fork and Vincent Gulch near Mount Baden-Powell.

A later attempt to build a road through the East Fork via Shoemaker Canyon, in the 1950s, was also aborted due to lack of funds.

Today the East Fork Road provides access to the Heaton Flats trailhead, a popular jumping-off points for visitors to the San Gabriel Mountains.

[6][7] The stretch of the river along and above East Fork Road is one of the most heavily used parts of the Angeles National Forest, and is visited by hikers, campers and recreational gold miners alike – as many as 15,000 per day in the summer, which has had considerable environmental impacts on the East Fork.