Regional MS4 Permit - Orange County

The Orange County MS4 Permit, Order No. R8-2009-0030, NPDES Permit No. CAS618030, as amended by Order No. R8-2010-0062, is currently in effect. The previous orders, including Order No. R8-2002-0010, have been rescinded except for enforcement purposes for violations that occurred when they were in effect.

There is currently a proposed Tentative Order for a Regional MS4 Permit that will regulate discharges in Orange County when adopted. Please see the Regional MS4 Permit page for more information. This page will be updated following Permit adoption.

NOTICE OF OPPORTUNITY FOR PUBLIC COMMENT ON PROPOSED ALTERNATIVE METHOD TO DEMONSTRATE COMPLIANCE WITH TIME SCHEDULE ORDER R8-2019-0050, AS AMENDED BY R8-2023-0063 AND R8-2025-0003, TO COMPLY WITH FECAL COLIFORM WASTE LOAD ALLOCATIONS FOR NEWPORT BAY FOR THE COUNTY OF ORANGE, THE ORANGE COUNTY FLOOD CONTROL DISTRICT, COSTA MESA, IRVINE, LAGUNA HILLS, LAGUNA WOODS, LAKE FOREST, NEWPORT BEACH, ORANGE, SANTA ANA, AND TUSTIN - The County of Orange submitted a proposal for an alternative method of compliance with the time schedule order to comply with fecal coliform waste load allocations in Newport Bay. The Santa Ana Water Board will accept written comments on the Proposal during a 30-day public comment period that begins on September 17, 2025, and ends on October 17, 2025. Comments must be received no later than 5:00 pm on October 17, 2025.

NOTICE OF OPPORTUNITY FOR PUBLIC COMMENT ON PROPOSED ALTERNATIVE METHOD TO DEMONSTRATE COMPLIANCE WITH TIME SCHEDULE ORDER R8-2019-0050, AS AMENDED BY R8-2023-0063 AND R8-2025-0003, TO COMPLY WITH FECAL COLIFORM WASTE LOAD ALLOCATIONS FOR NEWPORT BAY FOR THE COUNTY OF ORANGE, THE ORANGE COUNTY FLOOD CONTROL DISTRICT, COSTA MESA, IRVINE, LAGUNA HILLS, LAGUNA WOODS, LAKE FOREST, NEWPORT BEACH, ORANGE, SANTA ANA, AND TUSTIN - The County of Orange submitted a proposal for an alternative method of compliance with the time schedule order to comply with fecal coliform waste load allocations in Newport Bay. The Santa Ana Water Board will accept written comments on the Proposal during a 30-day public comment period that begins on June 25, 2025, and ends on July 24, 2025. Comments must be received no later than 5:00 pm on July 24, 2025.

NOTICE OF OPPORTUNITY FOR PUBLIC COMMENT ON PROPOSED CITY OF ANAHEIM STORMWATER CREDIT PROGRAM FOR NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM PERMIT AND WASTE DISCHARGE REQUIREMENTS FOR AREAWIDE URBAN STORMWATER RUNOFF WITHIN ORANGE COUNTY - The City of Anaheim has submitted a Stormwater Credit Program for review and approval by the Executive Officer. The Stormwater Credit Program would establish mechanisms, tracking, and controls to allow City-owned regional retention projects to generate “credits” that can be purchased by certain “new development/significant re-development” projects to satisfy the requirements set forth in the Orange County MS4 Permit. Stormwater Credit Program

The Model Water Quality Management Plan (WQMP) and Technical Guidance Document (TGD) were developed by the Permittees according to section XII.C. of the current Order. These documents govern the development and implementation of post-construction pollution controls for certain new development and significant redevelopment as defined in the Order. The Order, WQMP, and TGD emphasize the use of controls that support Low Impact Development (LID). Both documents are subject to periodic updates and amendments, subject to the approval of the Executive Officer and after public review. The initial approval and updates are shown below:

• May 19, 2011 – Approval of the WQMP, TGD, appendices, and errata sheet
• February 5, 2013 – Request for Approval of Changes to the WQMP and TGD
• Approval of February 5, 2013 Request for Approval of Changes to the WQMP and TGD

We can provide other documents upon request. These include:
• Previous permits
• Reports of Waste Discharge
• Annual Reports
• Monitoring Plans
• Water Code section 13383 Orders implementing statewide Trash Provisions
• Designation agreements for entities that lie within the jurisdiction of multiple regional water boards
• Administrative record for the adoption of orders.

For access to these documents, please contact the file review desk at FileReview8@waterboards.ca.gov- Email. For additional information regarding the Orange County MS4 program, please contact Hero Alexander at (951) 782-4419.

We want to hear from you!

Questions, comments, concerns?
Email: RB8-stormwater@waterboards.ca.gov

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