Rooftops to Rivers: Green Strategies for Controlling Stormwater and Combined Sewer Overflows

By Christopher Kloss, Crystal Calarusse, and Nancy Stoner
New York, NY (June 1, 2006)- Water pollution problems in the United States have evolved since the days when Ohio’s Cuyahoga River was on fire. Increasingly, water pollution from discrete sources such as factory pipes is being overshadowed by overland flows from streets, rooftops, and parking lots, which engorge downstream waterways every time it rains. This stormwater has nowhere to go because the natural vegetation and soils that could absorb it have been paved over. Instead, it becomes a high-speed, high-velocity conduit for pollution into rivers, lakes, and coastal waters.

Most U.S. cities have separate stormwater sewer systems through which contaminated stormwater flows directly into waterways through underground pipes, causing streambank scouring and erosion and dumping pet waste, road runoff, pesticides, fertilizer, and other pollutants directly into waterways. In older cities, particularly in the Northeast and Great Lakes regions, stormwater flows into the same pipes as sewage and causes these combined pipes to overflow-dumping untreated human, commercial, and industrial waste into waterways. Stormwater pollution has been problematic to some extent for as long as there have been cities, but the volume of stormwater continues to grow as development replaces porous surfaces with impervious blacktop, rooftop, and concrete.
Contaminated stormwater and raw sewage discharges from combined sewer overflows (CSOs) are required to be controlled under the Clean Water Act, but progress is slow because the problems are large and multi-faceted and because the solutions are often expensive. A substantial influx of additional resources is needed at the federal, state, and local levels, but fresh thinking is needed also. Some U.S. cities are already taking steps to successfully build green infrastructure into their communities.
Emerging green infrastructure techniques present a new pollution-control philosophy based on the known benefits of natural systems that provide multimedia pollution reduction and use soil and vegetation to trap, filter, and infiltrate stormwater. The cities already using green infrastructure are finding that it is a viable alternative to conventional stormwater management. Although used widely overseas, particularly in Germany and Japan, the use of green infrastructure in the United States is still in its infancy; however, data indicate that it can effectively reduce stormwater runoff and remove stormwater pollutants, and cities that have implemented green design are already reaping the benefits.
Related Resources:
Rooftops to Rivers: Green Strategies for Controlling Stormwater and Combined Sewer Overflows
Green Solutions to Stormwater Management