Last time, I highlighted the motivation of the Clean Water Act and the 1972 amendment that established the NPDES permit program. The flood control and water quantity focus evolved to require reductions in peak runoff rates from new developments to reduce downstream flooding impacts and conveyance facility sizes. Detention and retention facilities were designed to capture the runoff close to the source and control the release mimicking the predevelopment conditions.
Water Quality Becomes a Concern
Awareness grew that urbanized landscapes not only created flood hazards, but also degraded the water quality in the receiving waters . Storm water runoff is dirty! Detention facilities were modified to include water quality enhancements such as staged outfall controls for multiple storm events and pollutant filtering and settling features. These water features started to be viewed as a benefit offering an aesthetic amenity to developments.
New Responsibilities for Urbanized Areas
Large urbanized areas became NPDES permitted municipalities for their storm water discharges. They implemented operations and maintenance programs to reduce pollutants in urban runoff. They also engaged in public outreach campaigns to inform residents about land use practices that led to pollution. Advances in pollution reduction were being made, but we still had a long way to go to heal the impaired state waters.
In the next part in this series, we will look at water quality refinement and the return to the natural cycle.