Generally, wet weather sources such as CSOS, SSOS, stormwater systems and nonpoint sources are episodic, short-term discharges generated by rainstorm events. CSOS, SSOs and storrnwater can be controlled by transport or treatment facilities, best management practices (BWs) or a combination of both.

Nonpoint sources in rural areas can be controlled by the implementation of BWs such as improved, "no-tillage" practices on agriculture land; buffer strips to prevent polluted runoff and erosion; or wetlands construction. 

Reproduced courtesy from the Association of Metropolitan Sewerage Agencies (AMSA) - www.amsa-cleanwater.org. The Cost of Clean is also available on AMSA's web site or by contacting AMSA's National Office at (202) 833-AMSA.