Stormwater Management

    Development projects are required by National Pollutant Discharge Elimination System (NPDES) to manage stormwater (rainwater) runoff to protect local waterways during construction and after construction. The County implements the NPDES requirements through its development review process to ensure local waterways meet pollution prevention and flow management requirements.

    Stormwater discharges within Santa Clara County are regulated by two regional NPDES permits:

    • San Francisco Bay Municipal Regional Permit (MRP 2.0)
    • Phase II NPDES Permit (Central Coast)

    Use this watershed map to determine which of the two regional watersheds your project is located and use the accompanying documents below.

    For development projects located within the San Francisco Bay Watershed, use the following form and the associated stormwater management design guideline (requirements are changing on July 1, 2023):

    For development projects located within the Central Coast Watershed, use the following form and the associated stormwater management design guideline:

    For general stormwater management guidance, see the BASMAA’s Start at the Source: Design Guidance Manual for Stormwater Quality Protection.

    Please see BMP O&M Agreement​ for a copy of the Best Management Practices Operations and Maintenance Agreement used throughout the County.

    For additional informational on the County’s two NPDES permits or to report an illegal dumping or discharge, please refer to the County’s Clean Water Program website.​​​

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    About the Program

    The County's Clean Water Program is a function of the County government that exists to maintain compliance with a National Pollutant Discharge Elimination System (NPDES) Storm Water Discharge Permit and to promote storm water pollution prevention within that context. County compliance with the NPDES Permit is mandated by state and federal laws.

    What Is Nonpoint Source Pollution?

    "Nonpoint source pollution" is water pollution which occurs from many diverse areas of human activity within watersheds. These sources include illegal discharges, illegal dumping of solid or liquid waste, hazardous waste spills, chemical spills, agricultural operations, fertilizer application, soil sediment from construction projects, construction debris, improper grading, improper quarrying, sewage system and septic tank system discharges, vehicle and equipment washing, pesticide application, improper storage of solid waste, discharge of chemical substances, motor oil, antifreeze, paint, solvents, detergents, etc.

    Nonpoint Source Pollution is transported by the storm water system or other surface water flows to local streams and bays. In contrast, a particular ongoing discharge from a wastewater plant or industrial facility is considered a "point source" of water pollution.

    Nonpoint source pollution of streams and surface water is growing in importance as a national environmental issue. Unlike water pollutants that come from a single-point source (such as factories or wastewater treatment plants) nonpoint source pollutants originate from a variety of locations and are carried into storm drainage systems and creeks by storm water and other runoff. There are no treatment plants to manage nonpoint source pollution in our creeks, streams and bays. Prevention is the most effective way to reduce, minimize, and eliminate storm water pollution.

    Where Does Nonpoint Source Pollution Go?

    In northern Santa Clara County, nonpoint source pollutants flow into local creeks and streams, and eventually flow into south San Francisco Bay. Pollutants entering creeks and streams in the southern portion of the county ultimately flow to the Pajaro River and to Monterey Bay. Some of these pollutants, such as heavy metals and organic compounds, can concentrate to levels that are toxic to aquatic life, and contribute to significant environmental stress on streams and bays. These pollutants pose a serious problem for fish and wildlife dependent on Santa Clara County waterways, and for people who live and work near polluted streams or baylands. Nonpoint source pollutants may also infiltrate into the ground and contaminate the groundwater basin, which provides about half of the County's water supply. Pollutants can also contaminate the sediments that accumulate in flood control facilities, thus increasing maintenance and disposal costs.

    A Brief History of Clean Water Program Government Regulation

    In 1972 Congress adopted the federal Clean Water Act which requires pollutant discharges to navigable waters to be authorized by a National Pollutant Discharge Elimination System (NPDES) permit. Amendments to the act in 1987 include a section which required regulation of municipal and industrial storm water dischargers. It also required that individual control strategies (ICS) be developed by the storm water dischargers, to impose controls on nonpoint sources of pollution. This was in order to achieve compliance with water quality standards for "impaired" bodies of water. In 1989 the State Water Resources Control Board listed the south San Francisco Bay as impaired because water quality standards for heavy metals were frequently exceeded.

    The Basin Plan issued by the Regional Water Quality Control Board (Regional Board) in 1986 and its subsequent amendments, would later require the Program to submit proposals for determining pollutant loading, sources and control measures for nonpoint source pollution to the south San Francisco Bay.

    Recognizing that the proposed federal and state regulations would affect them all, north Santa Clara Valley's 13 cities, Santa Clara County and the Santa Clara Valley Water District - all jurisdictions which contribute runoff to the South Bay - joined forces to apply for a joint NPDES municipal storm water permit, rather than 15 separate ones.

    In June of 1990 the Environmental Protection Agency (EPA) conditionally ruled that the NPDES permit satisfied the Clean Water Act's requirement for an ICS. The NPDES Permit was reissued in 1996 by the State Water Resources Control Board, on behalf of the US/EPA. The 2000 re-issuance of the NPDES Permit occurred in 2001 by the RWQCB.

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    The Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP)

    This program is a multi-jurisdictional cooperative effort among the County, the Santa Clara Valley Water District, and thirteen north county cities, all working to improve the water quality of south San Francisco Bay and the streams of Santa Clara County, by reducing nonpoint source pollution in storm water runoff and other surface flows. SCVURPPP was established in response to two water quality regulations affecting the San Francisco Bay: the federal Clean Water Act, and the San Francisco Bay Basin Water Quality Control Plan (RWQCB Basin Plan).

    More info:


    SCVURPPP Programs

    The Santa Clara Valley urban Runoff Pollution Prevention Program's 15 participating agencies, or co-permittees, undertake various activities to address the requirements of their shared NPDES Permit. The goals of these activities include the following:

    • Eliminate illicit connections and illegal discharges to the storm drain system.

    • Promote public awareness of and participation in the Programs efforts to control nonpoint source pollution.

    • Identify and control storm water pollution generated by industrial and commercial activities.

    • Establish storm water management programs for public agencies to reduce the amount of pollutants that enter and accumulate in storm drains from governmental operations.

    • Identify and establish local regulatory control measures for activities that can contribute pollutants to the storm drain system, such as new development and construction, and residential, commercial and industrial activities.

    • Identify specific pollutant sources, such as those from transportation activities, and identify strategies to control them.

    • Monitor streams, storm drains, and land use sites to assess sources and effects of, as well as control and treatment options for pollutants in urban runoff.

    • Characterize and identify the groups of chemicals in nonpoint source pollution discharges which are toxic to aquatic life in streams.

    Presentations from Phase II Post-Construction Stormwater Requirements Workshop, February 10, 2014

    The following attachments are the presentations from the workshop that took place in Morgan Hill, CA.

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    • Oil and grease from automotive leaks and spills or improper disposal of automotive products.

    • Metals and hydrocarbons found in motor vehicle exhaust, brake and tire wear, paint, metal plating and motor oil.

    • Pesticides, herbicides and fertilizers from lawns, gardens, farms and improper disposal.

    • Soil erosion from lawns, hillsides and construction activities

    • Biological contaminants from animal waste and cross connections, and leaks or overflows from sanitary sewers and septic tank systems. (Call the local sanitary district or city public works department for sewer overflows and the County Department of Environmental Health (408) 918-3400 for septic tank system discharges.)


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    Erosion Prevention and Sediment Control

    Erosion prevention and sediment control are very important for grading operations that are conducted during the rainy season period, usually between October 1st until April 30th each year. Erosion Prevention and Sediment Control measures are an integral part of preliminary grading plans, and by ordinance must be shown on them.

    Sediment is a pollutant of concern in local streams, the San Francisco Bay and the Monterey Bay. Stormwater runoff from improperly conducted grading operations contributes to sediment pollution of local waterways. Increased sediment over the natural level is harmful to aquatic organisms and contributes additional mineral loads to streams and bays. It also causes additional expenses for stream maintenance, due to the expense of removal of excess sediment.

    Use of Best Management Practices (BMPs) for erosion prevention and sediment control reduces the sediment load in local waterways. Please see sections C12-411, C12-435(d), and C12-517 of the amended Grading Ordinance (attached below) for additional information.   For Further information on Storm Water Best Management Practices (BMPs) please visit 

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