San Pablo and Briones Reservoirs Loop is a 18.8 mile lightly trafficked loop trail located near Orinda, CA that features a lake and is only recommended for very experienced adventurers. The trail is primarily used for road biking and is accessible year-round.
This loop around the San Pablo and Briones Reservoir is intended as a road cycling trip, but there are hiking trails on the south side of the reservoirs that can be done on foot. Enjoy the scenic lake views. Going clockwise connect Bear Creek Rd with San Pablo Dam Rd and Castro Ranch Rd, Return via Alhambra Valley Rd.