Storm Water Mitigation Requirements

All development and redevelopment projects are obligated to comply with Federal, State, and Local storm water regulations during the planning, construction, and post-construction phases of development.  Storm water discharges to municipal storm drain systems, that are due to development are regulated by the San Diego Regional Water Quality Control Board (RWQCB).  Whereas, storm water discharges that occur as a result of construction activities are regulated by the State Water Resources Control Board (SWRCB).  The City of Oceanside is responsible for local administration of storm water mitigation requirements and has developed a Standard Urban Storm Water Mitigation Plan (SUSMP) as a resource document, which is designed to facilitate the implementation of the requirements of the RWQCB Municipal Permit.

Municipal Permit regulations make it necessary for projects to demonstrate compliance with storm water mitigation requirements prior to project approval or issuance of local permits.  Requirements that apply during the planning phase and prior to project entitlement include minimum standards for the implementation of Low Impact Development (LID) practices and the integration of flow control criteria designed to mitigate storm runoff peaks and durations from development sites. This unified LID approach combines site planning and design measures coupled with engineered, Integrated Management Practices (IMPs), such as bioretention facilities, flow-through planters, dry wells, infiltration basins, and cisterns.

Projects entering into the construction phase of development are regulated by the SWRCB and the City of Oceanside.  Construction projects are required to demonstrate both intended and ongoing compliance with City Grading and Erosion Control Ordinances, and applicable State Construction General Permit (CGP) requirements.  In addition, projects seeking approval of Grading or Improvement Plans are obligated, by RWQCB and City regulations, to demonstrate compliance with State requirements for long-term inspection, operation, and maintenance of permanent BMPs through the implementation of a Storm Water Operation and Maintenance Plan (O&M Plan).

The combined overall goal of the City and applicant is to produce a comprehensive storm water mitigation design that demonstrates compliance with the requirements of the Municipal Permit and is able to withstand an audit by the San Diego Regional Water Quality Control Board.

Project applicants are encouraged to coordinate with City Storm Water staff to enable the development a plausible storm water mitigation concept, prior to development and plan submittal.  Projects may elect to use the appropriate City Storm Water Mitigation Plan (SWMP) template as an aid to plan preparation.  In addition, it is suggested the project applicant consult with City Storm Water staff for assistance during each phase of development.   By implementing the unified LID design procedure, projects may develop a single integrated design that demonstrates compliance with Federal, State, and Local storm water regulations.

Avoid the Three Most Common Mistakes                

The most common and potentially costly errors made by the applicant during the entitlement (planning) phase of a project, with respect to storm water quality compliance are:

  • Not planning for compliance early in the design process. The applicant should devote serious consideration in the development of a strategy for storm water quality compliance before completing a conceptual site design or sketching a layout of subdivision lots.
  • Assuming proprietary storm water treatment facilities will be adequate for compliance; most are not. Lack of space, in itself, is not a suitable justification for using a proprietary treatment control Best Management Practice (BMP) on a development site, because the uses of the site and the site design can be altered as needed to accommodate bioretention facilities or other Integrated Management Practices (IMPs). In most cases, IMPs can be placed into required landscaping setbacks, easements, or other unbuildable areas.
  • Not planning for periodic inspections and maintenance of treatment and flow-control facilities. Consider who will own and who will maintain and operate the facilities in perpetuity and how they will obtain maintenance access. Select a long-term BMP maintenance mechanism that is acceptable to the City Engineer. The City Engineer will not accept a Treatment Control BMP as meeting the Maximum Extent Practicable (MEP) standard without providing assurance for long-term maintenance.

Requirements for All Development Projects                                                                

All development projects are required to implement permanent control measures to reduce the discharge of storm water pollutants to the Maximum Extent Practicable (MEP). All projects are required to include:

  • Implementation of Source Control BMPs
  • Inclusion of Low Impact Development practices that
    • Conserve natural features
    • Set back development from natural water bodies
    • Minimize site imperviousness
    • Maximize infiltration
    • Retain and slow runoff
  • Compliance with construction phase controls on sediment and other pollutants consistent with NPDES requirements.

All projects are also required to design the site drainage so that runoff from impervious areas such as rooftops, driveways, and parking lots; drains through vegetated or pervious areas prior to draining to a street or storm drain system.