• SF Water Board Seeks to Change Stormwater Permit Rules

  • BIA|Bay Area is preparing to respond to the San Francisco Regional Water Quality Control Board’s proposed changes to the municipal regional stormwater National Pollutant Discharge Elimination System (NPDES) permit. The association will participate in a public hearing set for Oct. 12, 2021, and water board staff will discuss the proposed permit changes during a BIA-members-only meeting on Oct. 20, 2021.

    To date, BIA members have raised two issues with the draft permit.

    The first involves a significant reduction in the type of project that qualifies as a “Special Project” under Category C. The current permit includes transit-oriented developments that meet specific density and floor area ratio levels. Such projects are eligible for stormwater treatment reduction credits that are critical in denser developments that lack the space needed for traditional bioretention facilities. The new permit limits Category C credits to affordable housing projects that meet certain deed restrictions and income criteria. This change could severely curtail transit-oriented developments at a time when the Bay Area seeks to increase housing densities within its existing communities as part of a state-mandated increase in home production.

    The second issue involves the definition of bioretention in the draft permit. Similar to existing rules, developers planning to install a bioretention stormwater treatment system must use a single 20-year-old prescribed sand/compost media design that covers 4 percent of the project’s impervious area. BIA members have identified new, technologically advanced systems that require less space but that provide similar or better water quality benefits. They are asking the water board to add language to the permit that allows for their use.

    Water board staff have said that the permit already has language that allows developers to seek permission for alternative bioretention systems but engineers say the loosely worded provision subjects applicants to excessive time delays, arbitrary decisions and uncertain outcomes. The new language that BIA members propose for addition to the end of Section C.3.c.i(2)(c)(ii) of the tentative order reads:

    “Innovative bioretention systems not meeting the BASMAA specifications above, or an approved revision to those specifications, must be vegetated, must achieve General Use Level Designation for Basic Treatment, Phosphorus Treatment and Enhanced Treatment from the Washington State Department of Ecology TAPE program, must be sized to treat the amount of runoff identified in Provision C.3.d without exceeding the TAPE approved hydraulic loading rate and must be designed to provide incidental infiltration where site conditions allow infiltration.”

    Lastly, the new permit proposes to eliminate grandfathering provisions included in previous permit updates. These exemptions allowed vested projects to proceed under the rules in effect at the time the developments were approved. BIA members with older projects that may have come under the grandfathering rules should be aware that these exemptions could end.

    In addition to participating in the public hearing and hosting a meeting with water board staff, BIA|Bay Area is preparing to submit a comment letter prior to the deadline of Nov. 9, 2021. Members with comments on these or other permit issues should contact Lisa Vorderbrueggen at lvorderbrueggen@biabayarea.org on or before the close of business on Nov. 1, 2021.


    1. San Francisco Regional Water Quality Control Board: https://www.waterboards.ca.gov/sanfranciscobay/
    2. SFRWQCB Oct. 12-13, 2021 meeting agenda: https://www.waterboards.ca.gov/sanfranciscobay/board_info/agendas/2021/October/10-12-13-2021.pdf
    3. SFRWQCB Stormwater Information Page:  https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/stormwater/
    4. Current NPDES permit:  https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/stormwater/MRP/R2_2015_0049_amended.pdf
    5. BIA|Bay Area Joint RPC Meeting Registration for Oct. 20, 2021: https://www.biabayarea.org/events/details/bia-bay-area-joint-east-south-bay-regional-policy-committee-oct-20-2021-1797
    6. Proposed NPDES permit: https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/stormwater/MRP/Compiled%20Order%20and%20All%20Attachments%20(RS-ACC).pdf