They also absorb sediment and nutrients that could harm rivers and streams. Prairie potholes are also sometimes called sloughs. They can be found in Montana, North and South Dakota, Iowa, Minnesota, and the Canadian prairies. Vernal Pools Vernal pools or ponds usually develop in the spring, when rain and melting snow fill in depressions in the ground. Vernal pools usually dry up as the weather gets warmer.
Vernal pools are often breeding grounds for frogs and other amphibians.
Some organisms in vernal pools are adapted to survive through the dry season. This protects the organisms until water fills the pond in the spring. Playas Playas are shallow, flat-bottomed basins found in the arid southern Great Plains of Texas, New Mexico, Kansas, Oklahoma, and Colorado. They get their water from precipitation and surface runoff. When there isn't enough rain they will dry out.