Take Tracy Blvd North from 205, turn left on Clifton Court Road, turn right on Cal Pack Road, follow it to the levy, go right almost to the end of the road. There is a gate just before the barrier. We put in where the three rivers come together (this may not be obvious from the road.) Once you put in go right, "upstream" which will take you to the barrier. Getting over the barrier can be a bit challenging on a strong outgoing tide but once you are over it you will bein some prime delta water!
Mapquest link showing Cal Pack Road. You can zoom out to see some of the other roads but it doesn't show all the names.