How do you prevent frogs from drowning in in-ground swimming pools?

You really can't. You can put a "skamper ramp" on your pool to help them get out but its hit or miss they'll see it.

There is a an ingenious lightweight, net device called Critter Guard that provides a ladder for frogs and other animals to use to climb out of a pool. Visit the Critter Guard Web site at or at Critterguard.net for Purchases and additional information.