We went to Del Valle Lake on October 7th, 2012 and spent the afternoon kayaking and hanging out by the lake. The Regional Park is located on the East Bay, south west of Livermore. There are trails in the park that you can take but we opted to picnic and hang out by the lake. There is a kayak rental shop where you can take a kayak out on the lake. There is also a small swimming area that is open year round (lifegaurds on duty only during the summer months).