Stormwater – Polution

Stormwater runoff from urban developments is a major source of water pollution.  Runoff from rain and melting snow traverses impermeable surfaces, picking up oil, grease, industrial discharges, airborne fallout, assorted chemicals and nutrients, bacteria, dirt, trash and other contaminants.  Stormwater runoff is derived from construction sites, small commercial sites, large urban mall parking lots, residential streets, and roadways and freeways.

The basis for stormwater management and treatment is the Clean Water Act (CWA), which was passed in 1972.  Section 402(p) was added to the Clean Water Act in 1987 to require implementation of a comprehensive two-phase approach for addressing stormwater discharges under the NPDES program.  These EPA stormwater regulations began in 1990.

Phase I established that an NPDES permit is required for stormwater discharge from municipalities with separate storm sewer systems that serve a population greater than 100,000, for large construction sites, and for certain defined industrial activities.  Under Phase II regulations (promulgated in November 1999), smaller municipalities and small construction sites are also required to obtain NPDES permits for stormwater runoff.  Phase II is scheduled to take effect March 10, 2003. 

The U.S. Environmental Protection Agency (EPA) is the federal governing body for the CWA.  However, much of the implementation and enforcement action has been delegated to individual states. 

Stormwater discharges to surface water are under increased scrutiny in the Pacific Northwest.  The main concern here is the effect of sediments on the life and reproduction of endangered fish, primarily salmon.  This recognition of the potential adverse effects of stormwater on streams and lakes