Engineering Division : Stormwater & Urban Runoff Management

Over the past century as urban areas continue to grow, urban growth has negatively impacted stormwater and urban runoff (water runoff from landscape irrigation, construction activities, etc.). Urbanization increases areas of impervious surfaces (roofs, parking lots, streets, etc.) changing the natural flow of stormwater by reducing the area of permeable surfaces for stormwater to naturally infiltrate into the soil. Without this natural filtration, stormwater and urban runoff are free to carry pollutants (landscape fertilizers, street oils, sediment, trash, leaves, etc) from lawns, parking lots, streets and construction activities into the storm drain systems which ultimately discharge into local creeks, rivers, and channels. This discharge is a significant source of water pollution which can harm the natural balance of the effected body of water.

Morgan Hill City Hall water-wise landscaping
to reduce irrigation and urban runoff

Aware of this situation, the federal government amended the Clean Water Act (CWA) in 1972 to include the provision that the discharge of pollutants to bodies of waters of the United States is unlawful, unless the discharge is in compliance with a National Pollutant Discharge Elimination System (NPDES) permit. In 1987 the CWA was further amended with provisions to regulate municipal and industrial storm water discharges, which includes discharges associated with construction activity. In November 16, 1990 known as NPDES Phase I, the Environmental Protection Agency (EPA) issued NPDES requirements to medium and large Municipal Separate Storm Sewer Systems (MS4s) serving 100,000 or more people. In December 8, 1999 known as NPDES Phase II, the EPA issued NPDES requirements to smaller municipal separate storm sewer systems (small MS4s) serving less than 100,000 people. The City of Morgan Hill is designated as a small MS4.

Under the California EPA, the State Water Resources Control Board (SWRCB) is the governing body which regulates the states NPDES permitting program. Made up of 9 Regional Water Quality Control Boards (RWQCBs), the City of Morgan Hill is under of the jurisdiction of the Central Coast RWQCB (Region 3). In March 23, 2005, Morgan Hill received its NPDES General Permit for a small MS4. Under the General Permit, the City is required to implement a Storm Water Management Program (SWMP) to prevent pollution in stormwater and urban runoff from entering the stormdrain system and protect the water quality of creeks and streams.

Detail information on the City’s SWMP and the State NPDES permit can be found in the following links:

• Storm Water Management Plan (SWMP) – Information on the City of Morgan Hill’s SWMP as required by City’s NPDES General Permit for a Small MS4.
• Storm Water Construction General Permit – How to comply with the state NPDES permit for construction sites greater than 1 acre.
• Notice Of Intent (NOI) – How to submit a NOI for the NPDES Storm Water Construction General Permit.
• Storm Water Pollution Prevention Plan - SWPPP Manual – How to develop a SWPPP Manual complying with the NPDES Storm Water Construction General Permit.
• Illegal Dumping (Illicit Discharge) Reporting – How to report illegal dumping of pollutants into stormdrains, creeks, and streams.
• State Water Resources Control Board (SWRCB) & Central Coast Regional Water Quality Control Board (RWQCB) – A direct links to the SWRCB and Central Coast RWQCB NPDES Stormwater Program.
• New Development and Redevelopment Post Construction Best Management Practices (BMPs) – Information on general guidance for selecting and implementing Best Management Practices (BMPs) to reduced pollutants in runoff in newly developed areas and redeveloped areas into stormdrains and waterways.

• Related Links - Other sources of Stormwater and Urban Runoff Management.
• News Links - Recent news and articles related to Stormwater and Urban Runoff Management.
• Definition - A dictionary of Stormwater and Urban Runoff terminology.

For questions and comments contact:
Charlie Ha (408-776-7337, email Charlie.Ha@morganhill.ca.gov)
City of Morgan Hill
Public Works Department
100 Edes Court
Morgan Hill, CA