The Clean Water Act Amendments of 1987 established the National Pollutant Discharge Elimination System (NPDES) Stormwater Program. The Act called for implementation in two phases: Phase I addressed the most significant sources of pollution in stormwater runoff and Phase II addresses other sources to protect water quality.
Phase I of the NPDES Stormwater Program began in 1990 and required medium and large municipalities to have separate storm sewer systems (MS4s) to obtain NPDES coverage.
The expanded Phase II program began March 2003 and required small MS4s in urbanized areas to obtain NPDES permits and implement six minimum control measures. An urbanized area as delineated by the Census Bureau is defined as a central place or places and the adjacent densely settled surrounding area that together have a residential population of at least 50,000 people and an overall population density of at least 500 people per square mile.
The City is studying approaches to prevent stormwater pollution and to clean up excessive pollutants in the drainage system before environmental damage occurs. A sampling and monitoring program has been implemented to determine the extent of stormwater quality problems existing in the community.