How to prevent rodents from drowning in my pool?

I found a dead rodent in my pool. Since it didn’t have a long tail, I’m guessing it may have been a gopher or something. Is there anyway to prevent rodents from falling into my below ground pool? B/c it’s pretty gross to see a dead furry creature floating in the pool just as I’m about to take a swim.
Teach it to swim. Nice help. Anyone have coupons for rodent floaties?