Briones Reservoir Loop is a 13.1 mile lightly trafficked loop trail located near Lafayette, CA that features a lake and is rated as difficult. The trail offers a number of activity options and is accessible year-round. Horses are also able to use this trail.
This loop, combining the Oursan and Bear Creek trails, is one of the longest in the region around Briones Reservoir. The route passes through a variety of terrain, from dense oak and bay forest near the reservoir's shore to open grassland high atop Sobrante Ridge. NOTE: Trail use permit required. Bicycles and dogs not allowed.
To do the entire trail you have to obtain a permit from EBMUD. Their office is by San Pablo reservoir and the permit is inexpensive and it's good for a couple of years. I've done this hike a few times and I've only seen a few people, all women, on the backside of the trail away from Bear Creek Rd. I rated it difficult only because of length. Not many people are prepared to do a hike this long. I've never had anyone else go along with me. There is all kinds of wildlife especially waterfowl and birds and the usual deer, coyotes, foxes and I've had a bobcat jump off a side hill about 20' in front of me as well. It would be best to take a friend along because of it remoteness and I've seen signs of mountain lions also. Take plenty of water, a permit and enjoy the hike. For safety there is a sign in board in the lower end of the lake when you go EBMUD property. This is a great fall through spring hike.