I live in central California and I fish a lot of canals here for bass. In one of the main canals I fish I had a similar problem fish were present, but finding anything with any size was a challenge. I solved this problem just through a lot of time and effort getting to know the area and in my case the larger Bass were not holding deep, they were holding a large floating mound of water hiasan that only has 5-7 feet under it. I also upsized my bait. I used to throw 4-5" worms and now I throw nothing but 7-8" plastics. Since finding where they were holding and uping my bait size my average has gone up dramatically in that canal.
As far as the white water is concerned Strippers will hold there, but the LMB tyically won't. I have noticed they prefer calmer water, or off on the side of the running water in eddies.
I hope i have been some help to you. Good luck.