Back in my lifeguard/instructor days we would find these in the pool every morning:
There was a lake across the road from the pool and every spring they would migrate looking for...? Inevitably two or three would fall into the pool every night and, even though they are amphibians, would drown trying to find a way out. Some ended up in the skimmers but the current wouldn't allow them out again. The swimboard (or stryofoam island) is a goog idea, but the critter has to be able to find it.
All we did was scoop 'em out every day until the hatch was done. No advice otherwise. Sorry.