There are so many places to check out in CA that I do not think any one person would have enough time in one life time to do them all. The low water at Melones might make it worthwhile to check out the old creek beds coming into the lake like between the water line and the trees.
Look up the "Chile Bar" area out of San Andreas CA. I've driven through the area, the sign posted there, plaque actually, says something like 12 miles of rich placer deposits. Then as I was further out the road I was on, there was a hard uphill turn and the road cut came right through an old placer deposit leaving a solid wall of round river rock on both sides of he road. It was startling to drive through the cut.
Just pick a spot where gold has been found in the area and give it a try. After all, it has been a lot of years of Ma Nature washing soil away since the 1849 rush, who knows what has been exposed or nearly exposed if you have a detector...........................63bkpkr
Al Lewis in the east bay, ya don't say. How close to Fremont?