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Municipal Stormwater Program

The Municipal Storm Water Program regulates storm water discharges from municipal separate storm sewer systems (MS4s) throughout California. U.S. EPA defines an MS4 as a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) owned or operated by a State (40 CFR 122.26(b)(8)).

Pursuant to the Federal Water Pollution Control Act (Clean Water Act) section 402(p), storm water permits are required for discharges from an MS4 serving a population of 100,000 or more. The Municipal Storm Water Program manages the Phase I Permit Program (serving municipalities over 100,000 people), the Phase II Permit Program (for municipalities less than 100,000), and the Statewide Storm Water Permit for the State of California Department of Transportation. The State Water Resources Control Board (State Water Board) and Regional Water Quality Control Boards (collectively, the Water Boards) implement and enforce the Municipal Storm Water Program.

Per Section J of the Small MS4 Permit, “This Order expires on July 1, 2018. If this Order is not reissued or replaced prior to the expiration date, it will be automatically continued in accordance with 40 CFR 122.6 and remain in full force and effect.” Therefore, all permit conditions and requirements will have to continue to be implemented until a new permit is adopted.

Permit Section J of the Small MS4 Permit further states “If you wish to continue an activity regulated by this Order after the expiration date of this Order, you must apply for and obtain authorization as required by the new permit once it is issued.” Therefore, once the new permit is adopted by the State Water Board, applicants will be required to submit a Notice of Intent, including all information required by the new permit, at that time.

Electronic Reporting


(Updated 5/15/18)

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