On June 18, 2025, the Ninth Circuit granted in part a petition for review brought by environmental groups challenging the refusal by the Environmental Protection Agency (EPA) to revise its existing pollution standards for certain industries. The decision stems from the EPA’s Effluent Guidelines Program Plan 15, issued in 2023, which outlined the agency’s plan for updating or maintaining effluent limitation guidelines (ELGs) under the Clean Water Act (CWA). The court held that the plan constitutes a final agency action, making it subject to review under the Administrative Procedure Act.
The panel rejected arguments from industry intervenors that the EPA’s planning actions regarding the ELGs were not judicially reviewable. Instead, the court found that the agency’s decision to leave in place existing ELGs—without proposing updates—was equivalent to a formal agency approval of the continued use of those standards. By reviewing and declining to revise the ELGs in Program Plan 15, the court ruled, the EPA plainly approved them within the meaning of Section 509(b)(1)(E), making the action final and appropriate for judicial oversight under the CWA’s statutory review provisions.
EPA Failed to Provide a Reasoned Basis for Inaction
While the court acknowledged that the EPA has discretion in deciding whether to revise outdated ELGs, it emphasized that this discretion must be exercised reasonably. In this case, the court found that the agency’s refusal to revise ELGs for seven industrial categories was arbitrary and capricious. The opinion highlighted three primary deficiencies: the EPA’s insufficient consideration of contemporary pollution control technologies, the EPA’s failure to address pretreatment standards applicable to indirect dischargers, and the EPA’s disregard of information about pollutants not currently encompassed by the relevant standards.
The court also singled out the EPA’s explanation for declining to revise standards for the plastics molding and forming industry, finding that the agency offered insufficient justification for maintaining outdated limits. As a result, the court remanded the matter for the EPA to either reconsider its position or provide a fuller explanation supported by the record.
Seven Industrial Sectors Now Face Renewed EPA Review
The Ninth Circuit’s decision specifically affects seven sectors: petroleum refineries; organic chemicals, plastics, and synthetic fibers manufacturing; inorganic chemical manufacturing; fertilizer manufacturing; pesticide chemical manufacturing; plastics molding and forming; and nonferrous metals manufacturing. While the court did not invalidate the existing standards, the EPA must now revisit its rationale for keeping them in place.
While the current standards remain in effect for now, the EPA is under a renewed obligation to support its decisions with a reasoned and evidence-based analysis. If the agency concludes that revisions are needed, a new rulemaking process will be required—potentially leading to stricter discharge limits for these sectors.
Implications for Industry and Future EPA Planning
The court’s finding that the EPA’s planning decisions are final and reviewable could have broader implications for how the federal agency conducts its biennial ELG reviews going forward. The EPA may need to offer more detailed justifications when deciding not to update longstanding standards. For regulated industries, the decision increases the risks of litigation and regulatory changes tied to outdated ELGs.
Although the panel ruled that petitioners waived their challenge to the EPA’s refusal to update new source performance standards—another form of ELG—the court left open the possibility of future challenges in that area if properly preserved. As the EPA begins to implement the remand, facilities operating under old standards should assess whether their practices align with current best available technology benchmarks and prepare for the possibility of rulemaking.
If you have any questions, or would like additional information, please contact one of the attorneys on our Environment, Land Use & Natural Resources team.
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