On Blackwater Sound in Key Largo, our neighbor two doors over had a seaplane and a couple of ultralight float planes in their basin. Never any problem with them. I used to worry more about rental jet skis running into the planes because the renters are totally focused on the water 10 feet ahead of them.
What really amazed me was Chalks Airline, a seaplane operation between Miami and the Bahamas. Those planes would land and take off regularly in the Port of Miami channel, which is very busy with powerboat and sailboat traffic. Somehow they always managed to find an open space, but if you were in the channel with a sailboat, it was pretty harrowing sometimes, wondering if they were going to clear you.
Those were professional pilots, though. I can see how it could be a problem, real or perceived, on a small lake if there were a lot of float planes making that lake their home port.
This is something I think about because Rick is obsessed with getting a seaplane. I am obsessed with changing his mind.