Model Water Quality Management Plan (WQMP)

For the most current provisions related to new development/significant redevelopment projects, please refer to the Model Water Quality Management (WQMP) and Technical Guidant Document (TGD).

What is the Model Water Quality Management Plan (WQMP) and Technical Guidance Document (TGD)?

The Model WQMP and TGD have been developed to aid the County of Orange, the Orange County Flood Control District, and cities of Orange County (the Permittees) and development project proponents with addressing post-construction urban runoff and stormwater pollution from new development and significant redevelopment projects that qualify as Priority Projects. The criteria for defining a “Priority Project” is provided in the Model WQMP and TGD.

The Model WQMP and TGD describe the process that Permittees will employ for developing a Project WQMP for individual new development and significant redevelopment projects. A Project WQMP is a plan for minimizing the adverse effects of urbanization on site hydrology, runoff flow rates, and pollutant loads. Development of a Model WQMP and TGD to provide guidance for the preparation of a Project WQMP is required by the two National Pollutant Discharge Elimination System (NPDES) permits held jointly by the Permittees administered by two Regional Water Quality Control Boards. The permits also require the development of Conceptual or Preliminary WQMPs prior to submission of a Project WQMP.

Orange County is split into two Regional Water Quality Control Board jurisdictional areas. North and Central Orange County (any area north of El Toro Road) is part of the Santa Ana Regional Water Quality Control Board (SARWQCB). South Orange County (any area South of El Toro Road) is part of the San Diego Regional Water Quality Control Board (SDRWQCB). The County of Orange (Unincorporated area) and cities of Laguna Hills, Laguna Woods, and Lake Forest have land area in both Regions.

Not sure which Regional Water Quality Control Board has jurisdiction over where your project is located? Click here to find outexplore


Different versions of the Model WQMP and TGD exist for North Orange County and South Orange County. Links are provided below.

Santa Ana Regional Water Quality Control Board (SARWQCB) – North of El Toro Road

In response to permit requirements from the SARWQCB, the County of Orange has prepared the following documents:

A Project WQMP template has been prepared to help guide you through the process. Go to the city website in which your project is located and you will be able to access their WQMP template. If your project is located in the unincorporated county land, please visit the OC Development Services Water Quality website. explore

San Diego Regional Water Quality Control Board (SDRWQCB) – South of El Toro Road

In response to permit requirements from the SDRWQCB, the County of Orange has prepared the following documents:

These documents are collectively equivalent to the “BMP Design Manual” required by the San Diego Regional MS4 Permit.

Check with the city in which your project is located in order to comply with their local Project WQMP requirements. A Project WQMP template has been prepared to help guide you through the process. Go to the city website in which your project is located and you will be able to access their WQMP template.

If your project is located in unincorporated county land in the South Orange County region, visit OC Development Services' Water Quality page. explore

A hydrologic model called the south Orange County Hydrology Model (SOCHM) has been developed to assist project proponents in selecting and sizing hydromodification control where applicable.


Mapping Portal to Support WQMP Preparation

To assist with preparing a conceptual/preliminary or project WQMP, geodata is now available for viewing and download through the OC Environmental Resources Data Portal explore (select WIHMP Data Map).


Environmentally Sensitive Areas (ESAs)

Your project may be subject to additional requirements if it:

  • Replaces or adds 2,500 square feet or more of impervious surface, or increases impervious surface by 10% or more, and,
  • Is directly adjacent to (located within 200 feet) or is discharging directly into an ESA, defined as an area such as those coastal areas designated in the Ocean Plan as an Area of Special Biological Significance, preserves or their equivalent under the Natural Communities Conservation Program (NCCP) or a water body listed on the Clean Water Act Section 303(d) list of impaired waters.
  •  Please click here for a map of Environmentally Sensitive Areas (as defined in the MS4 Permits) in Orange County.


We’re here to help!

In order to provide land developers, project proponents, and associated consultants and organizations with an overview of the new land development requirements in Orange County, the following training resource has been developed to orient readers to the contents of both the updated Model WQMP and the Technical Guidance Document. 

The training modules provide an overview of the level of detail that must be included at each phase of the WQMP preparation process, site and watershed assessment methods, LID BMP selection and prioritization methods, LID BMP design standards and performance criteria, regional LID BMP options, watershed-based plans, and LID alternative compliance options.

If you have a specific question that is not addressed in the training modules,  please submit your questions by creating an "Information Only" service request through myOCeServices.ocgov.com. explore