I used to fish the lower Potomac a lot 15 or 20 years ago there was a few worm water discharge pipes that came in from some of the factories I'm sorry I can't remember were they were I know one was just north of the mouth of Madawoman
from the reactor at the navy Base But the water was 60 to 70 degrease the bass would stack in there all winter I do remember there was at least 3 more spots like that to the north
I hope this will help you but like I said it's been a while since I've fished down that way These places might not be working any more
The more I think about it I do remember they were on the VA. side around Anacostiea and one was there near the sewage treatment plant