In a recent opinion, the Ninth Circuit Court of Appeals resolved a longstanding disagreement about the balancing required under Section 5937 of the California Fish & Game Code (“Section 5937”). Section 5937 requires that dam owners allow sufficient water to pass to keep fish “in good condition.” The Ninth Circuit’s ruling in San Luis Obispo Coastkeeper v. County of San Luis Obispo (Dec. 3, 2025, No. 24-7807) makes clear that Section 5937 does not categorically prioritize the preservation of fisheries over other beneficial uses of water, such as water supply for residential, agricultural, and municipal purposes.

In San Luis Obispo, a group of non-governmental organizations sued the County of San Luis Obispo, alleging that its operation of the Lopez Dam and Reservoir (1) constituted an unlawful take of steelhead under the Endangered Species Act and (2) violated Section 5937 by failing to release sufficient water to maintain fish in “good condition.” On November 27, 2024, the trial court granted a mandatory preliminary injunction, which required the County to implement extensive measures in its management of the Lopez Reservoir and Dam, including to develop a flow release plan and base flow release schedule, develop a plan to install a fish screen across the Lopez Dam, and develop a plan for studying volitional steelhead passage past Lopez Dam.

The Ninth Circuit vacated the preliminary injunction on both claims. In the second part of its opinion, the Ninth Circuit determined that the trial court’s balancing of equities, including water supply for residential, agricultural, and municipal purposes, was inadequate. Because it never “explain[ed] which evidence it found more persuasive or how the equities and public interest ultimately came out … the district court’s [Section] 5937 analysis remains unfinished.”

In reaching this conclusion, the Ninth Circuit directly addressed a longstanding, unresolved issue: whether the Cal Trout cases (Cal. Trout, Inc. v. State Water Res. Control Bd (1989) 207 Cal. App. 3d 585 (“Cal. Trout I”); California Trout, Inc. v. Superior Court (1990) 218 Cal. App. 3d 187 (“Cal. Trout II”)), mandates prioritizing water use for fisheries under Section 5937. Its answer was a definitive no. Because the Cal Trout cases address California Fish & Game Code Section 5946, its statement that the Legislature already balanced and prioritized fishery preservation “was about CFGC section 5946, not section 5937 [and] section 5946 cannot be mapped onto section 5937 based on the California Trout cases.” “[T]he state court has not explicitly held that § 5937 mandates placing the preservation of fish above the irrigation purposes of a dam.”

This ruling, along with the Fifth Appellate District’s decision in Bring Back the Kern v. City of Bakersfield, should resolve any and all doubt that water use under Section 5937 may require traditional balancing of competing uses.

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¹ Fish and Game Code Section 5946 requires water right licenses in Mono and Inyo Counties to be conditioned upon full compliance with Section 5937.