In a significant ruling interpreting the federal Endangered Species Act (ESA) and California Fish and Game Code (FGC) section 5937, a unanimous panel of the Ninth Circuit Court of Appeals (Ninth Circuit) on December 3, 2025 issued a decision vacating a preliminary injunction previously issued by the District Court for the Central District of California and remanded the case to the District Court for proceedings consistent with the Ninth Circuit’s opinion. The opinion is attached. ACWA, CSDA and CSAC authored and submitted an amicus brief (hereafter the “Association Brief”) in support of San Luis Obispo County (County), urging disapproval of the preliminary injunction. The Association Brief filed in support of SLO County is attached along with the Ninth Circuit’s opinion. Additional details about the Ninth Circuit’s ruling can be found below.
Factual/Procedural Background:
In August 2024, San Luis Obispo Coastkeeper and other environmental advocacy groups (hereinafter NGOs) filed an action in the District Court against the County alleging that the County’s operation of the Lopez Project (Project), and other public works in the Arroyo Grande Creek watershed, violated the ESA, FGC 5937, and various state law requirements related to protection of natural resources. The Project provides a local water supply to approximately 50,000 County residents and water for a number of other domestic and agricultural beneficial uses—many of which would be severely frustrated by the relief sought by the NGOs.
The NGOs moved for a mandatory preliminary injunction to require the County to change how it operates the Project by increasing water releases for instream flow, and taking numerous other conservation steps intended to benefit Steelhead in Arroyo Grande Creek. The District Court issued a broad preliminary injunction in December 2024 based upon its interpretation of the ESA and FGC section 5937. The County promptly appealed the issuance of the injunction to the Ninth Circuit.
The key components of the Ninth Circuit’s decision vacating the injunction issued by the District Court can be summarized as follows:
1. Preliminary Injunctions Are Generally Appropriate in ESA Cases If Take of Species Will Occur/Has Occurred:
The Ninth Circuit first summarized existing law in the Ninth Circuit, observing that preliminary injunctions, particularly prohibitory preliminary injunctions, are appropriate to prevent take of endangered species per the U.S. Supreme Court’s decision in TVA v. Hill, and that the normal balancing tests for injunctive relief must give way to Congressional intent to protect threatened and endangered (T/E) species. Of note, the Ninth Circuit appeared to assume, without expressly stating, that take of Steelhead Trout had occurred, or would occur, at Lopez Dam—despite a paucity of evidence on this point. The Ninth Circuit did not address the issue, discussed extensively in the Association Brief, of whether violating a non-regulatory recovery plan, by itself, is an appropriate proxy for “take” of T/E species, which the District Court appeared to believe, so that issue remains a live issue for future ESA litigation.
2. Presumption for Injunctive Relief Must Yield Where Relief Would Potentially Harm Other T/E Species:
The normal presumption in favor of injunctive relief, particularly where the relief sought is a mandatory preliminary injunction (e.g., an order specifying affirmative conservation actions that must be taken, rather than an order prohibiting take of T/E species) does not apply where the injunction has the potential to impact multiple endangered species. The Ninth Circuit held that a court must consider, based upon credible evidence, whether injunctive relief will potentially result in take or other adverse impact to all other T/E species potentially impacted by injunctive relief—which the District Court in this case failed to do. The District Court erred by focusing relief only on Steelhead and not considering and balancing the potential adverse effect of the injunction on the endangered Red Legged Frog and Tidewater Goby. This is an important holding, particularly with regard to Steelhead, since requiring additional flows to protect Steelhead can be detrimental to terrestrial T/E species that can be harmed by loss of dry land in riparian areas during breeding periods or when pulse flows wash away individual species or their eggs/young.
3. Traditional Balancing of Harms Is Required with Regard to Fish and Game Code 5937:
The Ninth Circuit agreed with the County of SLO, and the arguments in the Association Brief, that the district court did not properly base the preliminary injunction upon FGC 5937, determining that the District Court failed to properly analyze the balance of the equities and public interest factors required when considering whether to issue a preliminary injunction associated with alleged environmental harms. In coming to this conclusion, the Ninth Circuit rejected the NGOs’ argument and determined that caselaw pertaining to FGC 5946, which only applies in a narrow geographic portion of the state, does not apply generally to FGC 5937’s requirement to keep fish in good condition below dams. Perhaps more significantly, the Ninth Circuit rejected the NGOs’ argument that FGC 5937’s requirement to keep “fish in good condition” below dams creates a super-priority statewide in favor of fish preservation at the expense of all other beneficial uses of water, to include water supply for residential, agricultural, and municipal purposes. The Ninth Circuit remanded the case for a full balancing of harms per the U.S. Supreme Court’s decision in Winter v. Natural Resources Defense Council, Inc., 555 U.S. 7 (2008), in order to determine whether there was a violation of FGC 5937 and the appropriate remedy in the event of such a violation.
