“Fire road on the northeast side of the ridge in Shell Ridge.
— Mike Anciaux
The Corral Spring Trail starts near the trailhead at Indian Valley school in Walnut Creek. From the trailhead turn left (this is still Briones to Mt. Diablo Trail
). In a few hundred yards you'll come to a paved street. Take a right and the trail will immediately be on your left.
The trail slowly climbs up the side of Shell Ridge eventually running into Costonoan Trail
. It's a well maintained fire road.