So it’s an organized event that they knew about ahead of time? Though There’s definitely a safety issue there with what they’re doing, they should have an officer on sight for such things. If they didn’t want it going on, they wouldn’t issue the permit (I’d assume something like this would need one). Or they would close the area off, They’d have to go out and make a defined lane, and close the area off to the public during the event.
So if you know the event is goin on, stay out of their way or go to another lake. They should make it clear where the race is going on, and people should stay clear of those lanes. Same if I know there’s a tournament happening on the lake I want to fish, or when the locals have a boat party on the lake they live on.