There’s Lake Sonoma,
@Bob DBF knows more about than I do. I have no interest in fresh water lakes so I’ve never dived it.
Well it's 7mm farmer John territory for me, same as what I use in the ocean on the North Coast, and has a thermocline like Tahoe, it gets cold, but we normally did two dives, warm surface temps in the summer help. ymmv
Don't know if the OP is interested now, so for anyone else that might be interested.
I moved so I haven't be to Lake Sonoma for a while. The boat parking lot on the way to the ramp has stairs down to the water by the bridge, the walk back up... On the opposite corner of the bridge is a small dirt parking lot (free) but you walk down, and up, a hillside
It's low viz to zero viz as you go deeper. The bottom is silty mud, and if you scare the crawdads or hit the bottom, it's blackout time. It's worse during the rains in the winter, and we usually avoided that unless we HAD to dive.
On the good side, people have been tossing things off the bridge as long as the lake has been there, the debris can be used for attachment points for line. We eventually ran lines across the span down both sides of the bridge, with two cross lines one on each side of the last drop to the deepest part of the channel. The deepest spot is around 120', or so, depending on lake level. We left the lines in and they were broken or moved on a regular basis due to fishing.
As far as a point of interest, there is the cone forest, the final resting place of a dozen or two traffic cones someone tossed off the bridge. At different times we found two weapons, and some ammo, the corp of engineers rangers got to dread us flagginjg them down. After we found human remains they would just shake there heads and ask now what.
The area around the bridge is in a no wake zone so that's a real plus, also the corps of engineers require a dive flag. Because we entered and exited at the shore we usually ignored the flag, but when we were going to be on the surface out in the open, we would set a flag where we needed it to be.
It wasen't as much fun as the coast, but we had to dive somewhere, and it had its own charm. Besides, it's still diving.
Bob