Half a mile from the start of the crowded trail to the Bridge to Nowhere, you’ll find a junction with Heaton Flats Trail, which rises above the canyon carved by the East Fork of the San Gabriel River to offer big views and plenty of solitude.
Enjoy panoramic perspectives of some of the most notable peaks in the San Gabriel Mountains (including Mount Baldy, Mount Baden-Powell, and Iron Mountain) along the trail to a 4,000-foot high clearing on the ridge. The trail becomes faint beyond this point, so to avoid doing any bushwhacking, turn around for a 6-miles round trip trek with 2,000 feet of elevation gain.
Those with less time and energy may shorten the hike by venturing up the canyon wall only as far as the first saddle on the ridge for a 3.6-mile round trip hike with 1,000 feet of elevation gain. On the other hand, those with endless amounts of time and energy can continue up the ridge to the summit of Iron Mountain for a 15-mile leg-busting adventure with 6,000 feet of elevation gain.
Start as though you were hiking to the Bridge to Nowhere, leaving the large (and usually full) trailhead parking area at the end of Camp Bonita Road. Head north on the wide dirt service road 2N21, which parallels the East Fork of the San Gabriel River. After half a mile of level and slightly downhill hiking, the trail arrives at Heaton Flats Campground. The trail camp is home to the hike’s only marked junction. Turn right up Heaton Flats Trail, leaving East Fork Trail to begin climbing up the ridge.
Heaton Flats Trail weaves up the east side of the canyon, passing through chaparral and some of the hike’s only shade. After half a mile of switchbacks, the trail crosses a draw in the canyon wall and continues to climb. Views down the river expand as you reach a saddle on the top of the ridge, 1.3 miles and 1,000 feet above the campground.
Turn left when you arrive at the saddle, avoiding the use trail that heads to the right up a 500-foot rise on the ridge. After a sixth of a mile, you will pass a sign at the boundary of the Sheep Mountain Wilderness (a free wilderness permit is required to proceed).
The trail wraps around the east side of the ridge, heading north to quickly deliver the first views of Mount Baldy. The often snow-covered summit is the highest point in the San Gabriel Mountains. Coldwater Canyon and Cattle Canyon are below the ridge to the east. For those who decide to turn around at the saddle for the shorter hike, it is definitely worth carrying on for another quarter mile up the trail for the impressive view of Mount Baldy.
A switchback in Heaton Flats Trail lifts you to views facing southwest down the drainage of the East Fork of the San Gabriel River. The trail sticks to the east side of the ridge, leading to a level area where you can look down the west side of the ridge. On the other side of the canyon, you’ll spot Shoemaker Canyon Road, an ill-plotted dead-end road that passes through a tunnel in the mountain on the opposite side of the East Fork of the San Gabriel River.
A steep path pushes up the ridge’s spine, while the trail continues along the east side of the ridge, employing a switchback for a more gradual climb. The trail wraps around the west side of the ridge and ascends to a small clearing, 3 miles from the start, and 1.2 miles from the first saddle on the ridge. Located at just over 4,000 feet above sea level, the gap in the brush at this crest on the ridge has room for just a couple backpackers’ tents.
For the first time of the hike, you’ll get an expansive in-you-face view of Iron Mountain, looming to the north across Laurel Gulch, which drops to the East Fork of the San Gabriel River (across from Swan Rock). The faint line of Allison Trail can be seen tracing the skirt of the mountain on the opposite slide of the gulch, leading to another canyon housing Allison Mine, an old gold claim. Looking farther up the canyon carved by the East Fork of the San Gabriel River, you’ll have a good perspective of Mount Baden-Powell.
Beyond this rise on the ridge, the trail turns downhill for the first time and becomes faint and overgrown as it travels over rolling bumps in the ridgeline, eventually climbing to Heaton Saddle, an obvious notch 1.3 miles farther up the ridge.
Heaton Saddle is marked by exposed bleached rocks and is the last point along the ridge before the grueling assault on Iron Mountain, considered by writer John Robinson to be the toughest summit hike in the San Gabriel Mountains.
Rather than going through the undulations of the overgrown ridge trail, you may turn around when you reach the ridge crest. After gaining 2,000 feet over the last 2.5 miles, your legs will probably be ready to turn around, so take one last look at Mount Baden-Powell, Iron Mountain, and Mount Baldy before heading back the way you came.
A wilderness permit is required to access Sheep Mountain Wilderness. You may self-register for a permit at the kiosk at the south end of the trailhead, or obtain one at the East Fork Ranger Station located on the road to the trailhead (or at other ranger stations in the Angeles National Forest). A newer permit kiosk should also be available at Heaton Flats Trail Camp. This trail begins within the national forest so an adventure pass (day use pass) may be required to part at the trailhead, which can also be purchased at the ranger station. Dogs are welcome.
To get to the trailhead: From the 210 Freeway in Azusa, take exit 40 north on Route 39. Drive 11.6 miles north, passing the East Fork Ranger Station at the base of the San Gabriel Mountains. Pass San Gabriel Reservoir and turn right on East Fork Road. After 5.2 miles, when the road makes a sharp bend to the right, continue straight ahead on Camp Bonita Prairie Forks Road, sticking with the river for an additional 3/4 of a mile to the trailhead parking area.
Trailhead address: Camp Bonita Road, San Gabriel Mountains National Monument, Azusa, CA 91702
Trailhead coordinates: 34.23696, -117.765119 (34° 15′ 05.03″N 117° 44′ 32.26″W)
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