Trail: This “trail” is a paved service road the entire distance that closed to public automobiles. You can walk or bicycle it. Bikes with skinny tires are fine. Elevation gain is slight, except the last half mile as the trail rises to the top of the dam.
Length: 14 miles round trip
Elevation gain: 700 feet
Time: Year round
Facilities: Restrooms at the parking lot and three miles in. Also, a campground with restrooms is six miles in.
Other: Forest adventure pass required for parking.
From the 210 Freeway in Azusa, exit Azusa Avenue (Highway 39) and head north into the mountains. The West Fork parking lot is on Highway 39 approximately eight miles after entering the mountains and about one mile after the off-highway-vehicle staging area. You can see the trail from the parking lot, but it’s on the opposite side of the river. Walk back along the highway and over the bridge. The trailhead will be on your right.
Millions live near the San Gabriel River in the Los Angeles area. It flows out of the San Gabriel Mountains into Azusa, then through many communities, along the freeway named after it, before merging with the Pacific Ocean between Seal Beach and Alamitos Bay. This hike will take you within sight of the river’s headwaters and to the first dam these waters encounter.
Driving up Azusa Canyon into the mountains, everyone notices the Morris and the San Gabriel dams and their reservoirs. Many people do not know about the third dam, Cogswell, which is seven miles deep in the mountains from the nearest parking. The trail to Cogswell Dam is a waterside trail winding through a steep wooded river valley with many streams and waterfalls flowing into the valley, merging with the West Fork. This is a must-see trail of the San Gabriels. The ideal time is spring when the streams and waterfalls are at maximum flow.
The first mile is a popular picnic area, but the crowds thin out quickly after this. At two miles in, the fishing becomes catch and release only, wild trout area. Glen Campground is six miles in – a backpackers’ camp between the river, a stream and the mountains. Not far beyond Glen, you enter a mountain community. These homes are for rangers and caretakers of the dam. Stay on the main street as you pass through. Shortly after the community, you find yourself on top of the dam.
Enjoy the view, and keep a eye out for bighorn sheep that frequent this area. In the distance, beyond the reservoir, are the headwaters of the West Fork. These waters must pass five dams before reaching the ocean. Three are in the mountains, then the Santa Fe Dam in Irwindale and the Whittier Narrows Dam.
After leaving the mountains, much of the San Gabriel River has been converted to a concrete channel. This and the five dams allow it to be contained as it passes through the Los Angeles area, freeing the land along the river for development but at the cost of the river’s natural habitat and beauty from the mountains to the sea. At least here, in the mountains, in some areas, one can still see the San Gabriel River in its natural state.