This debate (mystery) can be easly solved. This will probably be a good project(experiment) for GW. Dig a new pond. Not to big. 1/4 ac should be good. Sides should be higher elevation than surroundigs to keep fish from swimming in from other water sources. Fill pond using only filtered well water. Set 24 hour survalence with inferred, heatseeking, thermal imiageing, nigt vision, motion sensetive cameras and record what happens. Just an idea.
