Fished the delta off a house dock in Discovery Bay on 8/25 and 8/26 for 15 bluegill to 1lb with most in the .25-.5 lb variety.
Fished the delta on 9/28 for bass and striped bass, but around 5:45 AM before my fishing guide (Rus Snyders) showed up, I jigged a dock at Russo's Marina for a few minutes and produced a .75ish lb bluegill.
Nice! Sometime this fall before the weather gets too cold, I'm going to take a day off work, drop the kids at school, then head out to the delta by myself for some bluegill. Will probably do Bethany. Very few people there, even on weekends, and lots of 'gills.
Bethany Reservoir is not far from Clifton Court Forebay, I'd guess 2 miles or so by road. It's up in the hills a bit, there are wind power generators near the far shore. You can hear them when a lot are going. Nice view of Clifton Court from the parking lot.
There is also a second fishing area with some picnic tables if you follow the road around the lake. There's car access around much of the lake and if you bike it I think you can get around the whole lake. When I get my float tube, I'm looking forward to fishing the outside of the weed line.
Bethany is a storage reservoir for the aquaduct, so water level can fluctuate by several feet in one day as they move water in and out, but it doesn't seem to affect the bluegill bite. Last time we were there, water was down 3 or 4 vertical feet, but in the late afternoon all of a sudden I noticed "Hey, that water is a lot closer than it used to be!" By the time we left a couple hours later, it was full. Those are some serious pumps!
I heard about the place one day when we'd gone out to Clifton Court with our kids and weren't even seeing nibbles from 'gills. A guy catfishing next to us said he'd heard there was a good bluegill bite at Bethany, so we headed up there.
Is there public fishing access at Discovery Bay? I'm not familiar with the Delta yet; we live on the SF Peninsula and have been in the bay area less than three years. Any other good bluegill spots, especially for kids, that I should try in the Delta?
Here's a Google maps link, or you can just go to Google maps and search for Bethany Reservoir, California.
Sorry for the late reply, yes, there is a public launch at Discovery Bay Marina, although I can't remember if there is a launching fee. When I get out on the Delta I usually launch out of Russo's Marina on Bethel Island (but that is always for bass fishing).
Thanks for the info on Bethany, I am going to have to try it out in the float tube (which I just ordered!)