My personal favorite trail would be on the road up to the <br />
camping/swimming/boat launch area. If you stop on top of the tallest point, <br />
there is a gate that is a ride road. If you go down some, there is a trail leading <br />
off to the left down the hill, it is pretty steep, then it leads to a fire road that will <br />
eventually go through an opening in a fence that is the beginning of a hiking <br />
trail. I have heard of that trail called hidden valley, I personally don't know what <br />
it's called. There is a lot of switch backs and is mainly a skinny single track on <br />
the side of a hill. There are some point where there are roots sticking out, but <br />
they are nothing big, and are easy to go over.
The park is located on Del Valle Road, just a few miles south of Interstate 580 in Livermore.
http://www.singletracks.com/item.php?c=1&i=4260