When land is undeveloped rain and melting snow will soak into the land or naturally flow to streams and rivers. When land is developed an impervious surface is created. An impervious surface is a man-made area that will not readily absorb water. Examples of impervious surfaces include paved areas, roof tops, streets and sidewalks. Developed land cannot absorb the water as easily, if at all, and many flow patterns are changed. In order to control the storm water, a storm drainage network has been built. These facilities must be operated, maintained, renewed and replaced in order to provide a safe flow of storm water.
To control storm waters and receive the benefits of that control, there is a cost. Since everyone in the City benefits, The Denver City Council passed an ordinance in 1981 which authorizes a storm drainage service charge to be collected from the owners of all improved parcels of land.