Never swam in a pond or stream, Michael, but did grow up swimming in Lake Michigan. We got the immune system boosters, but also waves, some big enough to body surf! (When you're a little kid.)

You missed one benefit of a non-pool environment: you could pee while still in the water. Just get out a ways from shore, pay careful attention to location, empty your bladder, and then be careful not to go back to that spot again. (Kid logic!)