From its sources in Mt. San Jacinto State Park Wilderness, the North Fork San Jacinto River and its tributary, Fuller Mill Creek, flow west and south into the San Bernardino National Forest. Congress added these streams to the federal system in 2009 as part of an omnibus bill signed by President Obama that protected 105 miles of Wild & Scenic Rivers and 750,000 acres of wilderness in California.
The North Fork and Fuller Mill Creek possess outstandingly remarkable scenic, wildlife, and ecological values. The streams flow through diverse scenery and life zones, from its source on the rocky sub-alpine slopes of Mt. San Jacinto, through mixed conifer forests, and into oak woodlands, chaparral and grasslands. The rich habitats along the stream support several endangered and sensitive species, including mountain yellow-legged frog, California spotted owl, southern rubber boa, and San Bernardino flying squirrel. Portions of the creek are easily accessible from scenic Highway 243 for day use recreation, with seasonal closures to protect mountain yellow-legged frog habitat. The Pacific Crest Trail crosses the upper reach of the North Fork in the state park.