Deep within the rugged canyons of the Sheep Mountain Wilderness in the San Gabriel Mountains, a monumental 120-foot concrete arch bridge stands stranded in mid-air over the rushing East Fork of the San Gabriel River. Built in 1936 to connect the San Gabriel Valley with Wrightwood, the road was completely washed away by the historic Great Flood of 1938—leaving this phantom bridge isolated 5 miles into the wilderness.
Trailhead & Expedition Logistics
- Distance: 10.0 miles round-trip (Out & Back)
- Elevation Gain: ~900 to 1,000 feet (Gentle gradient, rocky terrain)
- Trailhead: East Fork Parking Area / Heaton Flats (End of East Fork Road, Azusa, CA)
- Permits: California Adventure Pass or America the Beautiful Interagency Pass required for vehicle parking. Free self-issue wilderness permit required at the trailhead kiosk.
- River Crossings: 5 to 6 major river crossings each way. Expect thigh-deep water depending on seasonal snowmelt.
The Route: River Bouldering to the 1936 Arch
Starting at Heaton Flats, the trail follows the broad stony wash of the East Fork. Within the first two miles, trail markers disappear into the riverbed, requiring hikers to read the current and pick safe wading paths through cobblestone shallows and granite boulders. Water shoes with aggressive rubber grip and trekking poles are indispensable.
Arriving at the Bridge & Deep River Pools
Around mile 4.5, the trail ascends above the gorge onto a section of original 1930s asphalt roadbed before the soaring concrete arch comes into panoramic view. Beneath the bridge, natural granite swimming holes provide icy mountain water baths to recover before the return hike.
Safety & Leave No Trace Essentials
- • Flash Floods: Never hike the East Fork during or immediately following heavy rainstorms.
- • Water & Electrolytes: Carry at least 3 liters of water or a backcountry gravity filter.
- • Pack It In, Pack It Out: The Sheep Mountain Wilderness is sensitive habitat; pack out all trash and fruit peels.
