This is an easy 2.5 mile hike along the San Gabriel River, just south of the big dam.
The trail is just an old road, and it breaks up long before you can get to the dam.
To reach it, drive up N. Azusa Ave, aka Highway 39, aka San Gabriel Canyon Road, to 100 Old San Gabriel Canyon Road. Turn right at the El Encanto sign (that’s the name of an old restaurant), and park in the lot. The trail starts at the small picnic/overlook area.
https://simpsoncity.com/hiking/album/elencanto1.html – A review of the hike.
https://www.wca.ca.gov/azusa_wilderness_park – Plans for the Future