Colby Trail

Title

A Guide to Hiking the San Gabriel Valley

Puddingstone Reservoir
34.086922100000, -117.799772900000
If you’re looking to go “off the grid,” Bonelli Park is not for you. It’s basically the opposite of wilderness — but because of that, there’s a lot to explore.
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Bonnie Cove
34.125110000000, -117.856301700000
The Bonnie Cove Trails are a nice, relatively easy and scenic multi-use route through part of the South Hills Wilderness Area in Glendora.
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Colby Trail
34.153005200000, -117.845767100000
Managed by The Glendora Community Conservancy, a patch of grassland off the Colby Trail has become a hub of activity surrounding rare species rescue and management — namely, of the endemic Brodiaea filifolia, a "cluster lily" that's not only native to California but also seriously endangered.
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Potato Mountain
34.186802400000, -117.699584200000
If you’re the type of hiker that needs a destination at the top (or the end) of a trail, the concrete tank at the top of the so-called “Potato Mountain” (sometimes spelled “Potatoe”) may just do the trick.
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Skyline Trail/HaciendaHills
34.002414600000, -118.009722100000
The Hacienda Heights trailhead leads you up and along the rolling hills that overlook the surrounding valley communities, with plenty of shade.
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In Southern California, you just can’t beat our mountain ranges.

Whether you’ve got your eye on the peaks in the Santa Monica Mountains, the Santa Susanas, the San Bernardinos, the Sierras, the Verdugos or the San Gabriels … the Simi Hills or the San Rafael Hills … or the Temblor Range or the Coso Range (just to name a few) … we’ve got some of the best (and the highest) ones to summit. 

But sometimes you don’t want the undertaking of climbing a mountain.

Sure — climb every mountain, as they say. But you don’t have to only climb mountains! Because sometimes, a nice hill will do just fine.

And so, enter the great valleys of Southern California, which straddle the line between urbanity and wilderness — easier to get to, quicker to conquer, and with all their own unique habitats, species and histories to explore.

The San Fernando Valley (north of the Santa Monica Mountains) may hold the honor of being THE Valley, but here in SoCal, we’ve got more than one great valley — and if you head just 15 miles east of downtown L.A., you will discover the canyons and rolling hills of the San Gabriel Valley, just south of the foothills of the San Gabriel Mountains National Monument.

Here are five great places to explore on foot in the San Gabriel Valley that aren’t too far afield, yet have plenty of fodder for your sense of adventure.

1. Skyline Trail / Hacienda Hills, Puente Hills

Near the city of La Puente in the San Gabriel Valley, in the unincorporated bedroom community of Hacienda Heights, there's a habitat preserve in the Puente Hills that's right next to a landfill. And basically right on top of it. The landfill at Puente Hills is actually one of the country's largest, and — unlike the piles of trash of days gone by — is covered with earth daily. It's also constantly monitored for pollutants and any leakage of gasses (like methane). That’s why you might not notice it as you’re walking up and over those hills and through the trees. It is also oil adjacent, and relics from the old oil drilling days can still be seen. But for now, the Hacienda Heights trailhead leads you up and along the rolling hills that overlook the surrounding valley communities, with plenty of shade — that is, until you reach its peak, where power lines and other industrial reminders form a boundary between wildlife preserve and waste management. The Skyline Trail takes you along the landfill and to greater heights, or you can divert down the Native Oak Trail, which leads you to shady grove of — you guessed it — native oak trees. Unfortunately, much of L.A.'s native oak trees have been cleared for development or have succumbed to disease or torrential El Niño rains, so it’s nice to find them when you can. Just try to resist the urge to carve your name into the bark of these native trees. Other nearby trails in the Puente Hills include those that traverse Hellman Park and Sycamore Canyon in Whittier, though the Habitat Preservation Authority manages trails that stretch as far east as Rowland Heights and nearly to the county line that separates L.A. from Orange County.

Skyline Trail / Hacienda Hills

Sandi Hemmerlein

Skyline Trail / Hacienda Hills

Sandi Hemmerlein

2. Potato Mountain / Herman Garner Biological Preserve, Claremont

If you’re the type of hiker that needs a destination at the top (or the end) of a trail, the concrete tank at the top of the so-called “Potato Mountain” (sometimes spelled “Potatoe”) may just do the trick. Accessible via a trailhead located along Mt. Baldy Road in Evey Canyon, its first, shaded stretch leads up a fire road into Claremont Hills Wilderness Park — which is a welcome respite, since this area can still be sweltering, even in spring and fall (when the deciduous trees show off some of their color). At the juncture with Evey Canyon Motorway on the left, turn right to head to Potato Mountain, which becomes dry, dusty and sweaty (and, thanks to some erosion, slippery). Here, you struggle up steep stretches amid mountain-bikers trying to creep their way to the top, towards the tank. That concrete tank marks the top of the tater, where hikers leave behind actual raw potatoes that they’ve decorated and carved messages into. Think of it as a spudtastic way of signing a register or planting a flag at the summit, a starchy geocache that you can customize. Potato Mountain isn't really known as a destination hike, but Pomona College, which manages it as part of the Herman Garner Biological Preserve, is doing some important student research here on forest regeneration (with parts of it having burned extensively in the 2003 Williams Fire). That means you’ve got to apply for a free permit to go hiking there. And don’t forget to bring your own potato.

Potato Mountain / Herman Garner Biological Preserve

Sandi Hemmerlein

Potato Mountain / Herman Garner Biological Preserve

Sandi Hemmerlein

3. Colby Trail, Glendora

Normally, you don't see much in the way of wildflowers in Southern California as late as May. But this hasn't been a normal year. And that means the trails hold some unexpected — and long dormant — treasures for hikers to take the time to explore. Case in point: the Colby Trail in Glendora. Managed by The Glendora Community Conservancy, a patch of grassland off the Colby Trail has become a hub of activity surrounding rare species rescue and management — namely, of the endemic Brodiaea filifolia, a "cluster lily" that's not only native to California but also seriously endangered. The biggest threat to the thread-leaved brodiaea is development. Even the 2014 Colby Fire didn't destroy this small population — in fact, the falling ash might've actually helped it. The Colby Trail is the last place in Los Angeles County where you can see the flower, whose color ranges from lavender to blue. In the late spring, you'd normally be lucky to catch sight of a blossom or two, but this spring we're experiencing a bloom that reportedly only happens once a century — or, as some are saying now, once in a lifetime. It's, in fact, the city flower of Glendora — probably because of its rarity, since there are only a handful of significant populations found around the world. And in an interesting twist, the thing that kept the Colby Trail from becoming a housing development back in 1989 was the discovery of the brodiaea, which is the only city flower in California that's endangered. But it’s nice to know that sometimes, for some reason, some rare native plants manage to survive, against all odds. When you go off-trail through the stone-walled entrance to see the brodiaea in Glendora, at first you might only see the oat grass. The purplish petals are so low-lying that you can't see them from a distance — you basically have to stand right over them and look down. And it might take a few moments for your eyes to adjust. This area makes for a good turnaround point if you’re looking for just a short, satisfying jaunt, or you can keep heading up on the Colby Trail, deeper into the Big Dalton Wilderness, and make a loop with the Colby-Dalton Trail and Glendora Mt. Road.

Colby Trail

Sandi Hemmerlein

Colby Trail

Sandi Hemmerlein

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4. Bonnie Cove, Glendora

The Bonnie Cove Trails are a nice, relatively easy and scenic multi-use route through part of the South Hills Wilderness Area in Glendora, where you’ll find sunflowers intermingling with power lines on a moderately difficult climb to a nice scenic viewpoint. From the parking / staging area at the southern end, turn either left for the Bonnie Cove West Trail (0.3 mi) or turn right for the Bonnie Cove East Trail (0.4 mi) and loop around back to your car for a quick and efficient hike through land that was previously a private residence. That means you’ll see some non-native ornamental plantings like eucalyptus trees, but you’ll also meander through coastal sage scrub habitat, including pepper trees and laurel sage. To extend your hike, you can head up through Bonnie Cove to reach Alosta Canyon, the North Spur Trail or the South Hills Backbone Trail at the ridge of the wilderness area. The City of Glendora publishes a good guide for its local urban walking routes and wilderness trails within city limits, but some routes may go through private property, so be mindful of local signage.

Bonnie Cove

Sandi Hemmerlein

Bonnie Cove

Sandi Hemmerlein

5. Puddingstone Reservoir / Frank G. Bonelli Regional Park, San Dimas

If you’re looking to go “off the grid,” Bonelli Park is not for you. It’s basically the opposite of wilderness — but because of that, there’s a lot to explore. Perhaps best-known as the home of the Raging Waters theme park, these 1,975 acres at the east end of the San Jose Hills not only feature a man-made lake (a.k.a. Puddingstone Reservoir) as well as opportunities for boating, fishing, swimming and other aquatic sports, but they also include 14 miles of multi-use trails — all operated by the County of Los Angeles Department of Parks & Recreation. Remember that hikers must yield to horseback riders, but mountain bikers must yield to hikers. The best way to go is to simply walk around the reservoir, along the east and south shores, past the swim and ski beaches, the powerboat launch and “Sailboat Cove.” You’ll find plenty of picnic areas along your walk as well, so bring a snack and have a seat to watch all the activity that surrounds you. Be sure to look up to spot some of the small, private planes that are taking off from the adjacent (and historic) Brackett Air Field. And if you’re looking for some post-hike refreshment, stop at Norm’s Hangar Coffee Shop at the airport, which is open every day until 3 p.m.

Puddingstone Reservoir / Frank G. Bonelli Regional Park

Sandi Hemmerlein

Puddingstone Reservoir / Frank G. Bonelli Regional Park

Sandi Hemmerlein

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