I have a very large Black Walnut tree about 30' from my 2 acre pond. Last year I did not collect them and maybe a hundred + ended up in the pond. I never had any floaters so don't think it had any effect at all on the fish.
I've only had the property since last September and it has a couple dozen large BW trees. I plan collecting the nuts this fall. I was not looking forward to hulling them but the driveway method might simplify that. Never know what you'll learn on this site.