One of the local lakes here was Known for having large bass before our latest draught. It was also known for having many water snakes. My guess would be that either bass don't like snakes....or they had other food that was easier to get to and didn't eat the snakes for that reason.
Personally, all I ever caught there was crappie, and never saw a snake there...but we have been through two droughts since I got here, so the ecosystem of the lake may have changed.
Sean.