Is there a way to harness the movement of pool water or waterfalls to create electricity?

Jca asked a question about living off the grid and it got me thinking that maybe there is some sort of unit available that uses the water movement in a swimming pool to create power. Hopefully, minimally, supplying enough power to circulate the pool.

I’m looking for solutions that a homeowner can install, cost effective, and are not too large to make sense on a not very large piece of property.

Any other simple green ideas to create energy are welcome. Thanks.