Coal Canyon

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Water in the back of Coal Canyon
Oak tree and geology in Coal Canyon

Coal Canyon

    • Location: Corona, near the Orange/Riverside County boundary.  From the 91 Freeway, take the Green River exit and head west for half a mile to a parking lot on the right side of the road, a quarter mile before the entrance to the golf club.
    • Agency:  Santa Ana River Trail; Chino Hills State Park; Coal Canyon Ecological Reserve
    • Distance: 5.4 miles
    • Elevation gain: 600 feet
    • Difficulty Rating: PG
    • Suggested time: 2.5 hours
    • Best season: November – May (Friday through Monday)
    • USGS topo map:  Black Star Canyon
    • More information: here; here
    • Rating: 6

Coal Canyon is proof that a hike doesn’t have to be great to be interesting and well worth a visit.  This trip might not be on many “bucket lists” of hikes, but it has variety, a colorful history and, in less than two miles, it gets away from one of Southern California’s busiest freeways and into a secluded grotto that feels worlds away from civilization.

Long-time residents of north Orange County and Riverside County will recall an offramp to the 91 Freeway called Coal Canyon, which didn’t actually lead anywhere.  But while the offramp wasn’t of much use to humans, it was discovered to be a viable wildlife corridor between the Chino Hills and the much larger bulk of the Santa Ana Mountains to the south, and it’s been preserved for that reason. The offramp has long since been closed, but the occasional coyote, bobcat or perhaps even mountain lion still might be seen here.

From the parking area, head down Green River and pick up the paved Santa Ana River Trail, popular with cyclists. Unfortunately, for the next mile, you will be walking right next to the 91 Freeway. If nothing else, it’s a nice way to warm up your legs before beginning the bulk of the hike.

When you reach the old offramp, head left and go under the freeway. You now enter the Chino Hills State Park jurisdiction and head south into Coal Canyon on a fire road. Bear left at the first junction and then right onto a trail signed Big Mo. As you climb, you’ll still hear the noise from the freeway, but the sights of civilization start to vanish as you progress into the canyon.

At about a mile into the canyon, you reach the ecological reserve boundary. Just before you get to the sign, look for a path to the right, heading down onto the stream bed. Remember this spot for your return. Head upstream, which is a little tricky in spots but not too bad (just make sure you have sturdy shoes or boots). The exact route may be a little ambiguous, but keep in mind that as long as you stay in the stream bed, you won’t get lost. As you get deeper into the canyon, with the walls pinching in above, there may be some water trickling down the stream. This can help with the navigation, but remember that it can also make the rocks slippery and the terrain muddy, so be careful.

Finally, you arrive at the grotto. Even after heavy rains, the waterfall is likely to be not much more than a trickle, but it’s still a very nice spot to sit and relax for a little while before heading back.  On your return, if the air is clear, you may get a glimpse of Mt. Baldy rising up above the Chino Hills.

Text and photography copyright 2012 by David W. Lockeretz, all rights reserved. Information and opinions provided are kept current to the best of the author’s ability. All readers hike at their own risk, and should be aware of the possible dangers of hiking, walking and other outdoor activities. By reading this, you agree not to hold the author or publisher of the content on this web site responsible for any injuries or inconveniences that may result from hiking on this trail. Check the informational links provided for up to date trail condition information.


  1. This makes me want to get down to Coal Canyon right now; looks like another amazing spot to do some quality hiking! Great post and I look forward to sharing more with you:)

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