The American Toad doesn't occur in your area. If they truly are toads, they are some other species, probably Gulf Coast or Fowler's.
Toads "croak" to attract mates. Keep them from doing so and they will die out. That doesn't seem very humane, no matter how it's done.
Think of all the noise we humans make and how disturbing that must be to other species. Imagine if animals prevented us from flying airplanes, operating jackhammers, playing loud music, having barking dogs....Actually, it sounds rather nice!
You should feel proud that your pond is attractive to toads and welcome the fact that you are surrounded by the sounds of wildlife procreating. Think of it as an aphrodisiac!