Is my pond safe to swim in?

It's a small spring that has been there for years and is connected to a small stream by a stream of very soft mud. There are lots of frogs and this one big turtle, not a snapping turtle. And there are lots of tadpoles in it. About half of it is surrounded by woods but the other half is open, and there are lots of crawdad mounds near the bank. It is a freshwater spring but I don't know were the water comes out.