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Mt. Wilson - West Fork Loop

  4.0 ( 3 ) Favorite


10.6 mile 17.0 kilometer loop
75% Runnable


Ascent: 2,908' 886 m
Descent: -2,908' -886 m
High: 5,685' 1,733 m
Low: 2,896' 883 m


Avg Grade: 10% (6°)
Max Grade: 48% (26°)


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Trail shared by Alan Coles

On this run there is great scenery and flora and a nice stretch along the West Fork San Gabriel River.

Alan Coles

Features Fall Colors · River/Creek · Views · Waterfall · Wildflowers · Wildlife

Mt. Wilson Road is closed when there is snow or ice on the road. Observe the "No Parking" signs. An Adventure Pass required to park inside gate if open.


With over three times the yearly rainfall of the Los Angeles Basin, the north side of Mt. Wilson may seem more like a rainforest in this semi-arid range. The trail traverses a dense forest of bigcone spruce, oak, maple, sycamore, bay and alders in the riparian areas. This "upside-down" run starts from the top of Mt. Wilson and drops down to West Fork, San Gabriel River then returns back along the Gabrielino and Rim Trails.

Need to Know

Do not attempt the Rim Trail if there is snow or ice. If unsure, do the route in reverse order. There can be hazardous stream crossings during high water. Cosmic Cafe on Mt. Wilson offers food and refreshments but hours vary by season. Stay on trails and do not enter residential area on Mt. Wilson. Keyless ignitions may fail on top of Mt. Wilson due to electronic interference. Place key close to start button.

Runner Notes

Beware of ice or loose gravel on Rim Trail. A runner died on this trail.


Start from the top of Mt. Wilson by parking either in the lot inside the gate (Adventure Pass required) or in a turnout along the one-way road before it rejoins the 2-way road. Follow the road west to the road junction and locate the Kenyon DeVore Trail #11W13 on the north side (signed). Drop down 100 feet and there is a junction on the right with the Rim Trail extension. It leads east back to the parking lot inside the gate and can be used to access the trails when the gate is closed. Continue on down the Devore Trail as it passes under a nice forest of oak and bigcone spruce. About a half mile down the trail drops into Strayns Canyon passing a pump-house that supplies water to the top of Mt. Wilson.

The trail leaves the canyon bottom for a short distance offering good views to the west of San Gabriel Peak then drops back down into the canyon with a nice seasonal stream. There are small waterfalls along the way and mature maple trees that turn bright yellow, orange, and red in fall. Bay and alder trees dominate the streamside vegetation along with blackberry and abundant poison oak. After 2.5 miles the junction with the Gabrielino Trail is reached at an signed junction.

Go straight at the junction and continue downhill entering an area burned in the Station Fire (2009). Various ceanothus species along with scrub oak thrive in this fire recovery zone. The trail enters a nice oak forest and drops down to West Fork Trail Camp on the Red Box-Rincon Road. This shady camp on beautiful West Fork San Gabriel River has tables, stoves and a single vault toilet and makes a good lunch spot.

The Silver Moccasin Trail goes north from this site up Shortcut Canyon. The Gabrielino Trail crosses the stream and follows it east down along a meandering path passing under tall alders, oaks and bigcone spruce trees. The crystal clear and cold water splashing over large granite rocks makes this section a please to run along. There are ten crossings along the mile stretch down to Devore Trail Camp and they can be difficult when the water level is high. An alternative is to run the Red Box-Rincon Road east from West Fork Camp and reconnect where the trail crosses the road but that route is not as attractive. Watch for a nice waterfall dropping in from the south side about halfway between camps. Devore Trail Camp has stoves and tables and makes a nice lunch spot or a good place to take a break because it is a long climb back up to Mt. Wilson.

The trail turns south and climbs steadily under shady oaks, bigcone spruce and bay trees passing in and out of small canyons that usually have water running through them. Wildlife is abundant and deer, coyotes, squirrels and various birds can often be seen. The trail crosses the road and shortly arrives at Newcomb Pass. There are two picnic tables under shady oaks that make an excellent break spot.

Recent fire line work (Wilson Fire, 2017) mar this otherwise pristine spot. The Gabrielino Trail (NRT) goes south into Santa Anita Canyon. There is a spur road heading east that joins with the Red Box-Rincon Road in half a mile. Take the right turn onto the Rim Trail and heads west back to the top.

The Rim Trail stays mostly on the well-shaded north side occasionally passing along the ridge top with good views to the south. Near the top there are some steep slopes (dangerous if icy) then it passes around the observatory and joins the road. Follow the road west to the entrance. A pedestrian gate can be opened from the inside if the main gate is closed.

Flora & Fauna

Oaks, bigcone spruce, maple, bay, alder, sycamore trees. Abundant blackberry and poison oak. Some nice raspberries on Rim Trail. Mushrooms prolific after rains.

Deer, coyotes, squirrels and infrequently bear, mountain lion or fox. In spring there are copious amounts of lady beetles in the riparian areas covering dead logs.

History & Background

Mt. Wilson Observatory is world famous for many important astronomical discoveries. Tour information can be found at Cosmic Cafe. There is also a free museum. Many television and radio stations have transmitters on the summit.

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Volunteers clearing a 60" bigcone spruce near Devore Trail Camp.
Apr 19, 2019 near Sierra…, CA
Looking South towards the City of Angels
Mar 13, 2019 near Sierra…, CA
Waterfall along West Fork.
Apr 19, 2019 near Sierra…, CA
Meeting a deer along the Rim Trail.
Feb 29, 2016 near Sierra…, CA
Gabrielino Trail near Newcomb Pass. Shady with abundant poison oak.
Apr 15, 2018 near Sierra…, CA
Checking out the 150-foot Solar Telescope Tower at the Mount Wilson Observatory.
Mar 13, 2019 near Sierra…, CA

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