San Diego Region - Storm Water

The Storm Water Management Unit's main focus is in implementing permitting, compliance, and other activities to reduce pollutants in municipal, construction, and industrial storm water runoff. The Unit also provides important assistance in dispersing state grant funds to worthy projects that support activities for the reduction and prevention of storm water pollution. The Unit also regulates storm water runoff from Caltrans and Small MS4 systems (Phase II) through Statewide Permits issued by State Water Board. Both the industrial and construction storm water program have Statewide Permits and the Unit implements them through a combination of inspections, enforcement, and outreach.

The San Diego Regional MS4 Permit

The California Regional Water Quality Control Board, San Diego Region (San Diego Water Board) regulates discharges from Phase I municipal separate storm sewer systems (MS4s) in the San Diego Region under the Regional MS4 Permit. The Regional MS4 Permit covers 39 municipal, county government, and special district entities (referred to jointly as Copermittees) located in San Diego County, southern Orange County, and southwestern Riverside County who own and operate large MS4s which discharge storm water (wet weather) runoff and non-storm water (dry weather) runoff to surface waters throughout the San Diego Region. The Regional MS4 Permit, Order No. R9-2013-0001, was adopted on May 8, 2013 and initially covered the San Diego County Copermittees. Order No. R9-2015-0001 was adopted on February 11, 2015, amending the Regional MS4 Permit to extend coverage to the Orange County Copermittees. Finally, Order No. R9-2015-0100 was adopted on November 18, 2015, amending the Regional MS4 Permit to extend coverage to the Riverside County Copermittees.


The Regional MS4 Permit, Order No. R9-2013-0001, was adopted by the San Diego Water Board in 2013, the current permit cycle will conclude in 2018. In preparation for the review and reissuance of the Regional MS4 Permit, San Diego Water Board staff have developed the following tentative schedule:

Tentative Regional MS4 Permit Reissuance Schedule
Winter/Spring 2018 San Diego Water Board staff review of the 2018 Report of Waste Discharge (ROWD)
Spring 2018 Meeting(s), if needed, with CoPermittees/Stakeholders to discuss potential Regional MS4 Permit Modifications
May 2018 Release Administrative Draft of Tentative Order (This step may not be necessary and therefore skipped)
Meeting/Workshop on Administrative Draft of Tentative Order (This step may not be necessary and therefore skipped)
June 27, 2018 Order R9-2013-0001, as amended expires
Summer 2018 Release Tentative Order
Meeting/Workshop on Tentative Order
Public Comment Period on Tentative Order
Summer/Fall 2018 San Diego Water Board Staff Respond to Comments
Fall 2018 Public Adoption Hearing for Tentative Order




  • Administrative Record Index (The index contains links to individual documents. To have access to the documents linked to the index, please open with Internet Explorer.)






Pursuant to Provision E.3.c.(3) of Order No. R9-2013-0001, as amended by Order Nos. R9-2015-0001and R9-2015-0100, each Copermittee may be allowed to implement an Alternative Compliance Program within its jurisdiction which would allow Priority Development Projects to implement all or part of the structural storm water pollutant control and/or hydromodification management BMPs offsite instead of fully onsite. Pursuant to Provision E.3.c.(3)(a), the San Diego Water Board's Executive Officer must accept Water Quality Equivalency calculations before an Alternative Compliance Program may be implemented by a Copermittee within its jurisdiction. A final Water Quality Equivalency Guidance Document has been accepted by the Executive Officer, available below:

Phase II Municipal Storm Water Permit

Caltrans Storm Water Permit

Construction Storm Water Permit

Industrial Storm Water Permit

SMARTS Database

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  (Page last updated 1/30/18)