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State And Regional Board MS4 Permits, Which Require Numeric Water Quality Based Effluent Limits, Must Take Into Account Economic Considerations

Client Alert


On April 18, 2019, the Orange County Superior Court issued a ruling in City of Duarte v. State Water Resources Control Board - Case No. 30-2016-00833614-CU-WM-CJC and City of Gardena v. Regional Water Quality Control Board, Los Angeles – Case No. 30-2016-00833722. 

The Cities of Gardena and Duarte (“Cities”) challenged the municipal separate storm sewer system (“MS4”) permit requirements with respect to the Water Quality-Based Effluent Limitations (“WQBEL”) imposed by the Los Angeles Regional Water Quality Control Board (“Regional Board”) and the SWRCB (collectively “Respondents”).

The Court’s ruling was in favor of the Cities, finding that the numeric WQBEL compliance requirements in the Regional Board’s 2012 MS4 permit, as amended by the SWRCB in 2015, (“2012 Permit”) were “more stringent” than the Clean Water Act (“CWA”), that Respondents were therefore required to consider the factors listed in the California Water Code (“CWC”) § 13241 prior to adoption, and that Respondents failed to comply with the CWC in adopting the numeric effluent limitations requirements for the 2012 Permit by failing to consider those factors.


The SWRCB and the nine California Regional Water Quality Control Boards implement the CWA and the CWC.  The CWA establishes a basic structure for regulating pollutant discharges into United States waters. Pollutants may be discharged with a National Pollution Discharge Elimination System (“NPDES”) permit, which limits what can be discharged and sets monitoring and reporting requirements. An MS4 is a system owned by a public entity (or entities) which collects and/or conveys storm water.  Storm water discharge from an MS4 constitutes a “point source” and requires an NPDES permit, commonly known as an MS4 permit.  The Regional Board’s 2012 Permit required compliance with numeric WQBELs to implement applicable waste load allocations.

Numeric WQBEL compliance is “more stringent” than the applicable CWA requirements

While the CWA requires industrial discharges to meet the numeric effluent limitations in 33 U.S.C. § 1311, the CWA does not require municipal discharges to comply with such numeric effluent limitations (33 U.S.C. § 1342(p)(3).) Instead, municipal discharges “shall require controls to reduce the discharge of pollutants to the maximum extent practicable, including management practices, control techniques and system design and engineering methods, and such other provisions as the Administrator or the State determines appropriate for the control of such pollutants.” (Id. [Emphasis added].)  Because the 2012 Permit requires numeric effluent limitations for municipal discharges, while the CWA does not require numeric effluent limitations for municipal discharges, the Court found that the numeric WQBELs are a “more stringent” requirement than what is found in the CWA.

Because the numeric WQBELs in the 2012 Permit were “more stringent” than CWA requirements, the Court found that the Regional Board and SWRCB were required to consider the factors found in CWC § 13241 (citing City of Burbank v. State Water Resources Control Board (2005) 35 Cal.4th 613, 618; and City of Rancho Cucamonga v. Regional Water Quality Control Board-Santa Ana Region (2006) 135 Cal.App.4th 1377).  The CWC § 13241 factors include consideration of the following:

  • Past, present, and probable future beneficial uses of water.
  • Environmental characteristics of the hydrographic unit under consideration, including the quality of water available thereto.
  • Water quality conditions that could reasonably be achieved through the coordinated control of all factors which affect water quality in the area.
  • Economic considerations.
  • The need for developing housing within the region.
  • The need to develop and use recycled water. [Emphasis added]

The SWRCB And Regional Board failed to comply with the CWC in adopting the numeric effluent limitations requirements

The Court found that “[e]conomic considerations must begin with some kind of estimate of cost,” and that because Respondents did not proffer any kind of estimate of or projection of possible costs associated with the 2012 Permit, Respondents had therefore not complied with the requirement to factor economic considerations into the imposition of the conditions of the 2012 Permit.  While the 2012 Permit includes a finding that Respondents were not required to comply with CWC § 13241, the Court found that “Respondents’ conclusory findings do not reveal the route from evidence to action and are inadequate to support compliance with § 13241 … [i.e.] Respondents’ decision in approving the 2012 Permit is not supported by facts essential to sustain its decision.”  Thus, the Court did not uphold the numeric WQBELs in the 2012 Permit as they currently stand.

Importance and Implication of the Court’s Ruling

The 2012 Permit, and the numeric WQBELs therein, impacts 84 incorporated cities in Los Angeles County, as well as Los Angeles County itself and the Los Angeles County Flood Control District.

The Court’s ruling states the Regional and State Boards “are ordered to set aside the National Pollutant Discharge Elimination System Permit for Municipal Separate Storm Sewer System within the Coast Watersheds of Los Angeles County, except for discharges originating from the City of Long Beach MS4, Order No. R4-2012-0175, NPDES No. CAS 004001, as amended on June 16, 2015 by State Board Order WQ 2015-0075.”[1] The Court instructed the Petitioners to submit a proposed judgment based on the ruling.  On April 22, 2019, the State and Regional Boards asked the Court to set a hearing to allow the Boards to object to the ruling prior to the Cities’ submission of a proposed judgment.

If the State and Regional Boards appeal, any writ issued would likely be stayed pending the outcome of the appeal.


For further information, please contact Christine M. Carson from Aleshire & Wynder, LLP’s Water Practice Group at (949)223-1170.

Disclaimer:  Aleshire & Wynder, LLP legal alerts are not intended as legal advice.  Additional facts or future developments may affect subjects contained herein.  Please seek legal advice before acting or relying upon any information in this communication.

[1] Long Beach has a separate permit, which was not challenged and is not affected by this case.