Airport digging

If you have driven past the airport recently, you must have noticed that dirt is being tossed around.

The earth moving is being done to create a new drainage system. Above the excavator is digging a hole that will become a retention pond.

The new system, like the old, connects to a ditch, which is usually dry, that runs east of the fairgrounds until it dumps into another ditch that is just to the south of the south entrance to the fairgrounds.

It seems that almost every new construction project comes with some kind of retention pond. There is even one now in Iroquois Park for the water treatment plant. It must be a legal requirement. Does anyone know what the rules are that are giving us lots of little wetlands?