Waterflow

This view shows the whole concept of wetlands as special habitat and unique water filtration system. The top panels open to illustrate details.

HOW WETLANDS WORK
When it rains, the water cleans the dirt, oil and other pollution off the hard surfaces of buildings and streets.
It runs into the storm drains, which lead into the river or soaks into the ground and ends up in the water table.
When polluted water comes into wetland areas the plants and their roots filter and clean the water.
The water is held by a bowl of clay underneath.