Offsite Stormwater Alternative Compliance Program – Phase 2


SCH Number
Lead Agency
City of San Diego
Document Title
Offsite Stormwater Alternative Compliance Program – Phase 2
Document Type
NOP - Notice of Preparation of a Draft EIR
Document Description
Phase 2 of the Program would allow private or public development projects to meet their water quality and/or hydromodification performance standards with a combination of onsite flow-thru treatment control Best Management Practices (BMPs) and offsite ACPs. Offsite ACPs can consist of retention, biofiltration or flow-thru structural BMPs which detain, retain, filter, remove, and/or prevent the release of pollutants to surface waters. Natural System Management Practices (NSMPs), such as land restoration, stream rehabilitation or land preservation projects that restore and/or preserve predevelopment watershed functions in lieu of providing direct management hydromodification flow control, are also an acceptable type of ACP. An offsite ACP can provide stormwater pollutant control benefits, hydromodification flow control benefits, or a combination of the two, depending on its features. Permanent structural BMPs require on-going inspection and maintenance at regular intervals to maintain designed pollutant control and/or hydromodification flow control performance. For ACPs that involve stream rehabilitation, ongoing maintenance and operation of the improvements would occur at regular intervals in-line with project-specific regulatory agency permits and/or other program drivers. It is assumed that these projects typically require a higher level of maintenance in the first few years during vegetation establishment. The Phase 2 Program includes requirements for demonstration of ACP operation and maintenance mechanisms. Phase 2 of the Program also proposes an ACP credit system. The Clean Water Act allows for water quality credit trading to fulfill NPDES MS4 Permit requirements, but it does not include implementing provisions (i.e., a formal framework) for such a program. Through the City’s proposed WQE credit system, an offsite ACP that follows the specifications outlined in the San Diego RWQCB-approved WQE guidance document, may generate excess water quality credits. Excess water quality credits could be purchased or used by the PDP developer or property owner to comply with Regional MS4 Permit new/redevelopment requirements on the current or future project site(s). In addition, the Program allows for excess credits to be purchased or used by other developers/applicants or property owners to assist in complying with Regional MS4 Permit requirements on other projects. Once the amount of credits an individual ACP generates is approved by the City, the ACP owner may sell or trade the credits to another project located within the same credit trading area. Trading areas are no larger than the limits of a watershed management area. Credit trading limitations in certain watershed management areas may be applied based on Total Maximum Daily Load (TDML), Areas of Special Biological Significance (ASBS), and/or other water quality regulatory drivers or hydrogeographic features. The proposed City Stormwater Standards Manual presents the policy authority for Phase 2 of the Program. The Stormwater Standards Manual describes a) projects’ eligibility to participate in the Program; b) provides technical guidance as to how the Program is implemented; and c) outlines long-term maintenance and compliance efforts associated with Program utilization. Phase 2 of the Program is intended to enhance flexibility for developing properties within the City’s jurisdiction while concurrently incentivizing improvements to water quality in locations that otherwise may not see improvements in the near term (City of San Diego 2018a). The Program has been designed, and would be implemented to provide greater overall water quality benefit to the watershed when compared to implementing onsite BMPs on a project-by-project basis under the current Stormwater Standards Manual (City of San Diego 2018b).

Contact Information

Greg Johansen
Agency Name
City of San Diego Planning Dept
Job Title
Senior Planner
Contact Types
Lead/Public Agency


San Diego
San Diego
Other Location Info

Notice of Completion

State Review Period Start
State Review Period End
State Reviewing Agencies
California Air Resources Board (ARB), California Coastal Commission (CCC), California Department of Conservation (DOC), California Department of Fish and Wildlife, Marin Region 7 (CDFW), California Department of Parks and Recreation, California Department of Transportation, Division of Aeronautics (DOT), California Department of Transportation, Division of Transportation Planning (DOT), California Department of Water Resources (DWR), California Governor's Office of Emergency Services (OES), California Highway Patrol (CHP), California Natural Resources Agency, California Public Utilities Commission (CPUC), California Regional Water Quality Control Board, San Diego Region 9 (RWQCB), California San Diego River Conservancy (SDRC), California State Lands Commission (SLC), Department of Toxic Substances Control, Office of Historic Preservation, State Water Resources Control Board, Division of Drinking Water, State Water Resources Control Board, Division of Water Quality, State Water Resources Control Board, Division of Water Rights, California Native American Heritage Commission (NAHC), California Department of Fish and Wildlife, South Coast Region 5 (CDFW), California Department of Transportation, District 11 (DOT)
State Reviewing Agency Comments
California Native American Heritage Commission (NAHC), California Department of Fish and Wildlife, South Coast Region 5 (CDFW), California Department of Transportation, District 11 (DOT)
Development Types
Other (Citywide Storm Water compliance program)
Local Actions
Citywide Storm Water Compliance Program
Project Issues
Air Quality, Biological Resources, Coastal Zone, Cultural Resources, Cumulative Effects, Drainage/Absorption, Flood Plain/Flooding, Greenhouse Gas Emissions, Hydrology/Water Quality, Land Use/Planning, Mandatory Findings of Significance, Noise, Solid Waste, Tribal Cultural Resources, Vegetation, Wetland/Riparian
Local Review Period Start
Local Review Period End


Draft Environmental Document [Draft IS, NOI_NOA_Public notices, OPR Summary Form, Appx,]
Notice of Completion [NOC] Transmittal form

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