This is another way to get to the same trailhead: From 80, take the San Pablo Dam Exit. At the light, continue forward to San Pablo Dam Rd, and DO NOT TURN RIGHT or you will end up on Amador St.
San Pablo Dam Rd takes you through the El Sobrante main drag. Pass Morrow Dr and Barranca St to your right on your way to Hillcrest Rd. Make a right on Hillcrest Rd. and go up. Pass Bridgeway Circle and Quail Hill Ct. to your left. When you think you can't go any higher, you will find Bonita Rd to your left. Make a left on Bonita and go past several streets in a development. Make a left on Monte Cresta Ave and park at the end of the street. No bathrooms and no water. Bring your cell phone.