Worst Case (in my opinion):

Some fool interloper trespasser decides to go fishing or swimming and hurts themselves.
Court decides the pond is an "attractive nuisance".
You are held liable.

Who pays for insurance and liability?

Hope it works out well for everyone.

For even when we were with you, we gave you this rule: "If a man will not work, he shall not eat."

2 Thessalonians 3:10