Water Quality Equivalency Guidance

The 2013 MS4 Permit allows Priority Development Projects to satisfy onsite structural BMP performance requirements through participation in an Offsite Alternative Compliance Program. Development and implementation of this program is optional and at the discretion of each jurisdiction. To serve as a foundation for jurisdictions interested in pursuing such a program, a number of supporting elements have been pursued at a regional level. One such effort was the establishment of a Water Quality Equivalency (WQE) guidance document which provides applicants a method to demonstrate that construction of an offsite Alternative Compliance Project results in a greater overall water quality benefit than simply satisfying onsite structural BMP performance requirements associated with the Priority Development Project.

On December 17, 2015, the San Diego Regional Water Quality Control Board (RWQCB) accepted the Water Quality Equivalency Guidance Document for Region 9. On March 15 2019, the San Diego RWQCB accepted an updated version dated 2018. Both are available for download below. This guidance document establishes a mechanism to correlate quantifiable Alternative Compliance Project water quality benefits with Priority Development Project water quality impacts and ultimately demonstrate that the ACP benefits outweigh the PDP impacts. Pursuant to the requirements set forth in Provision E.3.c.(3)(a) of the Permit, the methods presented within this guidance must be incorporated as part of any optional Offsite Alternative Compliance Program developed by a Copermittee. Interested project applicants should reach out to their applicable jurisdiction for more specific information about these optional program elements.

For further information and questions regarding the development of the Offsite Alternative Compliance Program, please contact Sheri McPherson, County of San Diego, at Sheri.McPherson@sdcounty.ca.gov

Water Quality Equivalency Guidance (2018)

Archived Reference Material:

2015 WQE Guidance Material