Allison Mine Loop
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| | Difficulty:3A III (v3a1 III) Raps:5, max ↨80ft
Red Tape:No permit required Shuttle:None Vehicle:Passenger | ||||||||||||||||||||||||||||||
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| Condition Reports: | 24 May 2026
"Given the condition reports - we were sort of expecting to be the first Allison Gulch visitors since the Bridge to Nowhere opened after the Bridge Fir |
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| Best season: | Spring;Summer;Fall;Winter
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34.2713, -117.7285
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Introduction
Allison Mine is a secluded infrequently visited canyon off the very popular East Fork of the San Gabriel River. The canyon is good bit of work in rough terrain for just a few rappels but it's certainly the most adventurous way to return from seeing one of the San Gabriel's most elusive abandoned mine.
Two routes are available, both have their own challenges:
- The Brennen beta refers to the 'steep gully' route.
- This route take you up Allison Gulch on a lollipop route. The crux is a steep ridge to climb, switchback, and route-find your way up until precariously working along a thin shelf-trail east to the mine.
- The route from Heaton Flat Trail Saddle on the way up to Iron Mountain
- You must side-hill your way along a hot bush-whacky trail for a very long time, again with the occasional route-finding challenge.
- If you're up for a challenge, the upper section offers 6+ great rappels and a killer approach workout.
Approach
Park at the East Fork Trailhead. Follow the trail towards the bridge to nowhere, but at about the three mile mark, with Swan Rock on your left, find the trail up the Allison Gulch (34°15'46"N 117°44'47"W, elevation 2410ft). This is an obvious turnoff where the Allison creek joins the San Gabriel river, right after two successive river crossings. The trail up the gulch starts out okay, but after the first creek crossing becomes pretty washed out, so it involves some easy bushwhacking and scrambling. After about 3/4 mile in the creek, look out for the cairn on the north side, up on a rise just after the first big draw to the north (34°16'01"N 117°44'07"W, elevation 3060ft). This draw is obvious on a map.
From the cairn the trail is steep but clear. Tons of switchbacks and some scrambling, with a few false trails, but the main trail is very clear. After the trail levels and straightens out a bit, it traverses the northwest face of the steep Allison gulch narrows. There are some sketchy washed out sections, but with some fortitude the mine comes into sight, and finally the trail drops into the old settlement where building remains and campgrounds can be found (34°16'16"N 117°43'42"W, elevation 4110ft). This is one of the best and yet most remote camping spots in the whole San Antonio Ridge neighborhood. It's highly recommended that you camp here and explore the area at your leisure!
An alternate route involves hiking the Heaton flats trail towards Iron Mountain and peeling off to the left at a significant saddle, altitude 4582, along an unmaintained but very flat trail to the mine site. Great betas of both these routes along with additional mine info can be found below, or in the classic "Trails of the Angeles" by J.W. Robinson.
A third route, extremely strenuous but rewarding, involves continuing on the Heaton flats trail towards Iron Mountain, stopping on the wooded shoulder (34°16'27"N 117°43'00"W), bushwhacking across a steep but wooded slope following pretty nice game trails, then scrambling down a NNW facing scree chute (34°16'44"N 117°43'14"W) into the gulch. A large boulder corridor at the base of the chute signify the entrance to the canyon propper. Despite the additional elevation and 1.7 miles of rough hiking, this approach adds six great waterfalls and a lot more of that beautiful riparian canyon. As of April '17, all required raps are slung or bolted. Betas to Iron Mountain are available on various hiking sites.
Approximate trail specs:
Trailhead to Allison Gulch: 3 miles, 200ft
Gulch cutoff to Cairn: 3/4 mile, 700ft
Cairn to top of "steep part", where the trail levels off a bit: 1/2 mile, 900ft
There to the mine: 1/2 mile, 400ft
Total: 5+ miles, 2200ft
The first rap of the lower section is down a thousand feet or so from the campsite along the creek.
Descent
There are 5 rappels in the lower canyon section starting from the mine. Water is usually mid-calf deep, but has been reported waist deep in the past.
Lower canyon obstacle breakdown:
- 30ft rap, sling around rock DCR
- 30ft rap, sling around dead branch DCL. Soak in the scenery, this is one of the most stunning slots in the area.
- 20ft rap, sling around tree, middle canyon.
- 40ft rap from rock DCR, easy and pretty.
- 80ft rap around a massive overhead tree, muddy, easiest by far.
In the upper section there are an additional 5-6 rappels, all with slings or bolts as of April 2017.
Upper canyon obstacle breakdown:
- 25ft, high tree DCL or walk around it to the left. This should be bolted in the future. A cascade of carved granite scrambles and 1000ft of rock-hopping follows.
- 15ft, sling around tree DCL.
- 60ft, bolts DCL.
- 50ft, sling around tree DCR, beware of gear hanging on the branches. This tree should be "trimmed" in the future. About half a mile of walking follows.
- Three 15ft'ers, downclimb the first and third, sling around tree DCR on second.
- 50ft, sling around tree DCL, check out the mine entrance DCL, then downclimb DCL the little guy just downstream.
Proceed with lower canyon section from here.
Exit
The rest of the descent follows the creek and trails you came up in. Bring a headlamp in case it gets dark.
Red tape
Bring an adventure pass for the east fork trailhead if you plan to park on tarmac in the parking lot.
Beta sites
Chris Brennen's Adventure Hikes (St Gabriels) : Allison Mine Loop- Hugh Blanchard's Account of the Allison in "Local Goldmines We Will Never See"
- Super Amazing Map : Allison Mine Loop
- [1]
- [2]
- SummitPost.org : Allison Gulch
