A depression in the ground, after a good rain, will appear to be a shallow yet stable pond. Come back a few dry days later, however, and the pond will be even more shallow, or empty, as its sandy bottom can’t hold water. Though naturally occurring—this is how rainwater becomes groundwater—dry ponds are also man-made to deal with stormwater runoff in urban areas. While dry ponds are short-lived in dry climates, in the Southeast they can hold their water for a whole season or longer, drawing insects, frogs, alligators, and, because children come to watch the alligators chase the frogs, fences. What separates a dry pond from a wet pond is the type of soil: dry ponds are sandy and porous, while wet ponds have clay bottoms.