First google hit looks promising. Traffic through worries me, but probably shouldn't be a problem. Sounds like it has some old quarries, if they aren't too ragged it could be good for quests (caves, monster lairs).
The official Page from the walnut creek city website makes it seem less useful, but that's what diplomacy is for.
There is a park ranger who gives tours, so we could find out when that is, go on tour and ask what would be necessary to have games in the area. The central section is a wildlife preserve, though, and dogs have been attacked by coyotes so we may have trouble stumbling into a den somewhere. Luckily, borders make good deterrents without risking harm to the animals.
Tours look like they happen on a monthly basis, and it says reservations are required for groups of five or more. We may be able to spin a 1/month, 1/6 months or 1/year event, and even get free advertising on their site! I dont know though. We aren't yet as good as the McAbees, and there are no camp sites or toilets. That's... Less than fun.
I work on an iPhone. Sometimes it "corrects" my spelling in all the wrong ways.