Stormwater Program

Orange County Stormwater Program

The Orange County Stormwater Program was initiated in 1990 as a cooperative local government response to the 1987 Amendment to the Federal Clean Water Act (CWA). This amendment extended the provisions of the CWA Section 402 National Pollutant Discharge Elimination System (NPDES), issuing a permit to the municipal storm drain system operators, also known as the Municipal Separate Storm Sewer Systems (MS4s), thereby making local governments responsible for the quality of their stormwater discharges.

Administration & Compliance

In California, these stormwater programs are administered by the State Water Resources Control Board (SWRCB) and 9 regional boards that issue NPDES-MS4 permits and enforce regulations within their respective regions. South Orange County lies within the jurisdiction of the San Diego Regional Water Quality Control Board (SDRWQCB). This regional board issued the 1st municipal NPDES-MS4 permit in 1990 for the "Orange County Stormwater Program," a partnership between the County and South Orange County cities, including the City of Rancho Santa Margarita. NPDES-MS4 permits are issued for a 5-year term with the current Fourth Term Permit issued on December 16, 2009.

In compliance with the NPDES-MS4 Permit, the City of Rancho Santa Margarita has developed a comprehensive Stormwater Program that exemplifies the high value that is placed on clean water and improving water quality. This program includes a Local Implementation Plan (LIP) that regulates urban water runoff in and around the City.

For additional information on the City's Stormwater Program, please contact the Public Works Department at 949-635-1800, extension 6501.

Program Resources

  • To report chemical and hazardous materials spill, please call 911.
  • To report water pollution, please contact the County of Orange hotline at 877-897-7455.
  • For mosquito and rodent issues, please contact the Orange County Vector Control at 714-971-2421.

2018 Integrated Regional Water Management Plan

To view the 2018 IRWM Plan, please click here.

Learn more on how to do your part to protect our precious water by using the Orange County Watershed/Public Education website.