In a lengthy and highly technical published opinion filed August 5, 2025, the Fifth District Court of Appeal partly reversed and partly affirmed a judgment that had upheld the State Water Resources Control Board’s (“State Water Board” or “SWRCB”) adoption of the “State Policy for Water Quality Control: Toxicity Provisions” (the “Toxicity Provisions”), which policy in relevant part required use of a new “Test of Significant Toxicity” (“TST”) in analyzing a type of pollution known as “whole effluent toxicity.” Camarillo Sanitary District et al. v. State Water Resources Control Board (2025) ___ Cal.App.5th ___.
Background and Court’s Primary CWA Holding
Whole effluent toxicity does not refer to a specific chemical pollutant but defines when the combined effects of all pollutants in the water is deemed toxic. Whole effluent toxicity testing is required in various contexts within the complex web of federal and state statutes and regulations addressing water pollution and quality control, including in connection with wastewater discharge permits issued pursuant to the National Pollutant Discharge Elimination System (NPDES) governed by the Federal Clean Water Act (“CWA”; 33 U.S.C. § 1251 et seq).
Key legal points and principles driving the Court’s CWA-based decision in this case were that (1) the challenged Toxicity Provisions were expressly intended to broadly apply and require use of the TST with respect to all inland surface waters, enclosed bays, and estuaries and coastal lagoons – including both waters of the United States (WOTUS) and surface waters of the State – within the State of California, and (2) relevant federal regulations also address in detail whole effluent toxicity testing methods, and as a general matter the CWA allows California and other states to impose higher, but not less stringent, pollutant standards than the federal regulations. In addressing plaintiffs’ challenges to the SWRCB’s Toxicity Provisions made under the CWA, state water laws (i.e., the Porter Cologne Act), the state Administrative Procedure Act (“APA”), and CEQA, the Court ultimately held that the Toxicity Provisions violated the CWA to the extent that the TST could not be used to measure whole effluent toxicity in NPDES proceedings, but otherwise rejected the state law challenges, including those made under CEQA.
As further basic background, whole effluent toxicity testing is unique in that it is a “method-defined analyte,” meaning that it both measures and defines toxicity. Unlike tests that use instrumentation to conduct chemical-specific numerical measurements of a water sample, whole effluent testing is biological in nature in that it measures the aggregate effect of a discharge on aquatic organisms (e.g., minnows, water fleas, green alga) by exposing a test population and counting how many die or become immobilized. CWA regulations expressly prohibit modification of an approved CWA analytical method for a method-defined analyte. (Citing 40 C.F.R. § 136.6(b)(3).) After lengthy analysis of the relevant federal regulations and guidelines governing whole effluent toxicity testing, the Court of Appeal concluded that they authorized only two approved “statistical endpoints” – the no observed effect concentration (NOEC) and the 25 percent inhibition concentration (IC25) – and four analytical methods. The Court deemed all of these to be inconsistent with the TST required by the SWRCB’s Toxicity Provisions, which would generally define an ambient water sample as toxic if the survival, reproduction, or growth response of the test organisms was less than or equal to 75 percent of the test organisms’ response in the control sample.
Important to its rather involved and technical analysis (which cannot be done justice here), the Court found that the TST would impermissibly change the very definition of toxicity under the federal regulations by changing the identified statistical endpoints by which toxicity was measured and defined, which would, in turn, also result in significant discrepancies in test results, such that many samples found toxic under the federally-approved regulatory criteria would not be found toxic under the TST. Hence, the Court held that – although it might permissibly be employed in other contexts – the TST could not be used in NPDES permitting because its “regulatory definition of toxicity [was not] equal to or more stringent than the [federally] approved NOEC [or IC25] for hypothesis testing.”
The State Water Board’s Certified Regulatory Program and CEQA Analysis
Moving on from its overarching holding, which was driven by federal law supremacy and the CWA’s fundamental function as a regulatory “floor” in the context of water pollution regulation, the Court rejected all the state law challenges to the Toxicity Provisions, pointing out, inter alia, that the TST could have application extending beyond the scope of federally regulated WOTUS. (Given this blog’s subject matter, I won’t discuss the Court’s analysis and holdings rejecting appellants’ state water law and APA challenges, but will discuss in detail its CEQA analysis and holdings, which comprised about 12 pages of its 59-page published slip opinion.)
The State Water Board’s (and regional boards’) basin planning process, including adoption of related rules, regulations and policies – i.e., per the Court, the “entire planning process related to water quality control” – is a Natural Resources Agency-certified regulatory program. (CEQA Guidelines, § 15251(g); see also 23 Cal.Code Regs. §§ 3775-3782 [implementing regulations].) As such, the Court held the State Water Board may substitute a plan or other written documentation containing environmental information required by its program for the EIR generally required by CEQA. Accordingly, the Court rejected appellants’ arguments that the Board was not authorized to use a substitute environmental document for CEQA review of its adoption of the Toxicity Provisions, as based on a too-narrow construction of the scope of the Board’s exempt regulatory program. Per the Court: “We… conclude that the State [Water] Board may utilize the exempt regulatory program identified as the “Water Quality Control (Basin)/208 Planning Program of the State… Board and the Regional Water Quality Control Boards” when formulating and adopting state water quality control policies under Water Code section 13140.”
Having determined the State Water Board could properly proceed without a formal EIR under CEQA, the Court next considered – and ultimately rejected – appellants’ substantive challenges to the adequacy of the Board’s consideration of the potentially significant environmental effects of its adoption of the Toxicity Provisions as state water policy. Central to this analysis was the regulatory requirement that a substitute environmental document include, inter alia, analysis of “reasonably foreseeable methods of compliance” by regulated entities and of “any reasonably foreseeable significant adverse environmental impacts associated with those methods of compliance[.]” (Citing 23 Cal.Code Regs., § 3777(b)(4)(A), (B).) The Court found these requirements consistent with CEQA’s requirement to analyze foreseeable impacts of an initial project and its prohibition of “piecemealing’ to avoid environmental scrutiny. (Citing Laurel Heights Improvement Assn. v. Regents of University of California (1988) 47 Cal.3d 376, 396.)
Guiding the Court’s perusal of the State Water Board’s analysis was Ebbetts Pass Forest Watch v. California Department of Forestry & Fire Protection (2008) 43 Cal.4th 936, 954-955, a case involving foreseeability issues regarding future pesticide use in the context of a substitute environmental document. The Court found relevant that case’s stated principles “[r]egarding speculativeness and its opposite, foreseeability[.]” In brief, future actions that are “reasonably foreseeable in general terms” warrant “a general discussion of the act and its possible environmental effects, but [the substitute environmental document] need not include a detailed analysis of specific acts that cannot reasonably be foreseen at the time… [it] is prepared.” A detailed analysis of every action that may conceivably occur is not necessary: “Where the exact parameters of general foreseeable future actions cannot confidently be predicted, [CEQA’s] full-disclosure goals… may nonetheless be met with an analysis that ‘acknowledges the degree of uncertainty involved, discusses the reasonably foreseeable alternatives… and discloses the significant foreseeable environmental effects of each alternative, as well as mitigation measures to minimize each adverse impact.” (Quoting from Ebbetts Pass.)
Here, the State Water Board’s primary environmental analysis declined to “engage in speculation or conjecture” and noted that since its regulations did not specify actual methods of compliance it would provide analysis at “a general, programmatic nature” level of specificity. The Board explained project-level impacts would vary with the specific project; the size, location, and type of discharger; and the affected environmental resources around the project site. It found that while it would be speculative to estimate such details as to any particular possible toxicity controls, the “major category of reasonably foreseeable [compliance] methods… for all non-stormwater NPDES dischargers” would be “an increase in monitoring, testing, and laboratory analysis.” Notwithstanding its findings that the choice of future toxicity controls was speculative and not a reasonably foreseeable compliance method, the State Water Board’s report discussed possible controls that may have potentially significant impacts in 13 resource areas, including air quality, agricultural and forest resources, GHGs, hydrology and water quality, and transportation. It did not stop there, however, and included further discussion of what it determined was the reasonably foreseeable method of compliance (additional monitoring) and the potential for additional toxicity control projects (which would depend on myriad factors that would differ depending on the particular discharger, such as location, facility size and type, existing regulatory controls, existing effluent nature and quality, etc.), and generally explained it was likely dischargers would select projects that cost less and have lower environmental impact. “In light of these unknowns, the State [Water] Board reviewed five prior ‘discharger upgrade projects that broadly capture the size, types, and locations of [potential] upgrades… to aid the qualitative assessment of potential impacts’” and concluded from those projects’ environmental documents that nearly all their identified potentially significant impacts were found less than significant with mitigation; further, any significant and unavoidable impacts were unrelated to treatment upgrades or concerns about speculative methods of compliance.
Following this analysis, the State Water Board’s report provided a 100-plus-page environmental checklist discussion that generally divided environmental considerations between those related to reasonably foreseeable monitoring and those related to speculative toxicity controls. It discussed and concluded, inter alia, that compliance with the Toxicity Provisions is anticipated to have a potentially significant loss or conversion impact on agricultural or forestry resources, but not on creating conflicts with agricultural or timberland zoning. It also detailed expected impacts and related mitigation, while explaining that potential impacts from construction, operation and maintenance of new or upgraded toxicity controls were not considered reasonably foreseeable compliance methods, but were discussed “for purposes of informing decision makers and the public of any possible [resulting] effects…, however unlikely.”
The State Water Board’s report discussed and ultimately concluded (1) monitoring would have no effect on agricultural/forest resources (requiring no mitigation); (2) structural control construction had a low probability of substantial impacts (since it was expected to occur by non-storm water NPDES dischargers mostly within existing facilities or disturbed areas, rather than new lands, and other dischargers would not require new construction); and (3) operation and maintenance of any toxicity controls would take place within facility footprints (and thus not impact surrounding resources), and for nonpoint sources would be de minimis and have no impact. In summary, though, the State Water Board conservatively stated compliance was anticipated to have a potentially significant impact.
The Court of Appeal’s CEQA Holdings
The Court held the State Water Board’s impact analysis satisfied the principles set forth in Ebbetts Pass. The analysis “determined that reasonably foreseeable methods of compliance with the Toxicity Provisions do not include any future construction projects that were required to cure any future toxicity determinations because those projects were too speculative” but nonetheless “provided an analysis that discussed the degree of uncertainty involved, the reasonably foreseeable alternatives available to those needing toxicity controls, the significant foreseeable environmental effects of each alternative as shown through prior projects, and the effects of mitigation efforts from those projects.”
Per Ebbetts Pass, “a full disclosure of all impacts and mitigation efforts is not required when the exact parameters of generally foreseeable future actions cannot confidently be predicted.” Here, the State Water Board’s analysis “provided a wealth of relevant information covering those activities it deemed too speculative to be reasonably foreseeable means of compliance” with the Toxicity Provisions, and its discussion constituted substantial evidence in support of that “too speculative” conclusion. The Court further held that, even it if found that conclusion improper, it would still find no error in the Board’s impact and mitigation analysis which, as set forth in its environmental checklist discussion, “readily meets [CEQA’s] disclosure requirements for generally foreseeable impacts that cannot be accurately predicted.”
Finally, the Court rejected appellants’ remaining arguments alleging “a laundry list of alleged CEQA violations” as waived for their failure to “provide[] any independent analysis or discussion of those assertions.” (Citing Estrada v. Public Employees’ Retirement System (2023) 95 Cal.App.5th 870, 889.)
Conclusion and Implications
This case generally illustrates the scientific and legal complexity of water pollution and quality regulation in California under “the unique cooperative federalism model embodied in the nationally governing [CWA] and the many ways to challenge modifications to the rules[,]” including under the federal CWA, the state law APA, the state Porter Cologne Act, and, of course, CEQA. As to the CEQA aspects of the Court’s opinion, it provides valuable CEQA-compliance guidance to agencies with certified regulatory programs adopting new regulations that will trigger generally foreseeable future compliance actions the parameters of which are speculative. The robust analysis of the State Water Board’s substitute document in this case provides a good template for compliance with CEQA’s disclosure requirements in this somewhat murky area of the “foreseeable/ speculative” spectrum.
