Urban Runoff

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Background Dry weather urban runoff is contaminated water that is generated from day-to-day activities such as over-irrigating lawns, washing cars and hosing down driveways. This untreated water flows into stormdrains. The flow can be filled with pathogens (disease causing organisms), toxins, pesticides and other materials that can contaminate beaches and lead to beach postings and beach closures.

 A 1999 Huntington Beach closure investigation indicated that the dry weather urban runoff flowing into the Pacific Ocean may have caused or contributed to shoreline contamination and high bacteria levels. As a result, the Orange County Sanitation District (OCSD) began the Dry weather Urban Runoff Diversion Program.

Since 1999, OCSD has successfully reduced bacterial exceedances along Orange County’s beaches.

OCSD’s Program As part of a regional best management practice (BMP) to control urban runoff, OCSD has agreed to reroute the dry weather urban runoff from stormwater pump stations and storm channels located in the cities of Huntington Beach and Newport Beach into OCSD’s sewer system for treatment.

The Urban Runoff Program began in December 1999 when OCSD’s board of directors agreed to temporarily accept dry weather urban runoff into its sewer system for treatment. In April 2000, the board adopted a resolution for accepting urban runoff on a long-term basis during dry weather.

The resolution was designed to minimize adverse impacts on coastal beaches and public health, while maintaining the high quality of OCSD’s primary function –collection, treatment and disposal of wastewater. On September 27, 2001, the board adopted a second resolution, which included the following requirements:

  • The amount of dry weather urban runoff flow will not exceed 10 million gallons per day.
  • Dischargers will not be required to pay any fees associated with the approved discharge of dry weather urban runoff into OCSD’s sewer system if the total volume of all dry weather urban runoff discharges does not exceed four million gallons a day.
  • OCSD will accept urban runoff throughout the year on days when it is not raining.

Urban Runoff Quality OCSD tracks and monitors the quality of urban runoff discharges into its sewer system since the inception of the Urban Runoff Program. This is to ensure compliance with OCSD’s local limits and to assess impacts on the ability to meet ocean discharge and other regulatory compliance requirements.


Discharge Permits The discharger must complete an application to obtain a wastewater discharge permit and supply required technical information. The permit issued by OCSD will set the terms and conditions of OCSD’s wastewater discharge regulations.

Diversion Flows Range between 0.2 to 3.0 million gallons per day (mgd).

OCSD Urban Runoff Legislation Assemblyman Tom Harman introduced California State Assembly Bill 1892, in January 2002. The bill allows OCSD to acquire, construct, and operate facilities that divert and treat urban runoff and return the water for beneficial use.