It's public, and the cost of admittance is very low. (I think the girls were $1 each.)
It has a beach-like entrypoint where you basically just walk into the water. There's a "lazy river," with a current that pulls you along a curved channel. And a whirlpool area will swirl you around in a circle.
And most amazingly, it wasn't overrun with people, despite the fact that it's in the middle of Piedmont Park (Atlanta's equivalent of Central Park).
That wouldn't be the case here. It would be mobbed with humanity if it were in the Big Apple.
This is why we can't have nice things.