Regional MS4 Permit

The Santa Ana Water Board has regulated pollution from urban areas through three separate permits issued to each of the three counties and their cities within the watershed. These permits were first issued in the 1990s and have been renewed four times since then. The permits are known as Municipal Separate Storm Sewer System (MS4) permits. An MS4 is a conveyance or system of conveyances (including roads with drainage systems, city streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) usually owned by a city or county. The Santa Ana Water Board is renewing the MS4 permits for a fifth time. Instead of issuing three separate permits, the Santa Ana Water Board is proposing to adopt a single MS4 permit for all the counties and cities in the Santa Ana River watershed.

This webpage will be updated when new actions are taken. The proposed MS4 permit will go through public review before the Santa Ana Water Board adopts it.

Keep up to date on this project by joining our mailing list. Please go to https://public.govdelivery.com/accounts/CAWRCB/subscriber/new?qsp=santa_ana and sign up to receive notifications on "Region 8-Stormwater-Regionwide MS4 Permit".

Tentative NPDES Permit and Waste Discharge Requirements for Discharges of Pollutants in Urban Runoff from the Municipal Separate Storm Sewer Systems in the Counties of Orange, Riverside, and San Bernardino (NPDES No. CAS618000)  – On March 1, 2024, staff of the Santa Ana Water Board released a tentative permit for regulating discharges of pollutants in stormwater and urban runoff from Municipal Separate Storm Sewer Systems (MS4s) in Orange, Riverside, and San Bernardino Counties on a regionwide basis. On March 5, 2024, staff of the Santa Ana Water Board announced the release of the tentative permit and a Board workshop in a message sent via GovDelivery. This message initiated a 60-day public comment period that would have ended May 4, 2024. A Board workshop occurred on March 15, 2024. In response to comments during the March 15th Board workshop, Santa Ana Water Board staff extended the public comment period deadline from May 4 to July 3, 2024. The Santa Ana Water Board held a board workshop on September 13, 2024, to discuss and solicit feedback on the Tentative Permit.

A staff report is also available that provides a non-technical summary of the draft permit:

• Summary Staff Report

To review the reports of waste discharge, please contact the file review desk at FileReview8@waterboards.ca.gov

For additional information regarding the Regional MS4 Permit program, contact Hero Alexander (951) 782-4419.

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