2026-06-28

A Listing Upheld:

The Steelhead, the Diversion, and the Cost of Fighting

A Water Policy Series — June 2026

Introduction

On June 12, 2026, a Los Angeles County Superior Court judge denied a petition that almost no one outside Ventura County was watching, and in doing so settled a fight that had run for the better part of five years. The United Water Conservation District — a public agency that captures the Santa Clara River behind a concrete diversion and spreads it across the aquifers beneath the Oxnard Plain — had asked the court to throw out California’s decision to list the Southern California steelhead as endangered. The court refused.¹ It was the district’s second defeat on the same question, and it leaves a fully listed fish, a constrained dam, and a water agency that now has to share the river on the fish’s legal terms.

The case is small in the way most consequential water cases are small: a single diversion, a single agency, a few hundred surviving fish. But underneath it sits the question every California water board will eventually face. When a species that depends on the water you divert is headed for an endangered listing, do you fight the listing — or do you get ahead of it? United Water chose to fight twice and lost twice. This article walks through what the court actually decided, why the district resisted so hard, what the listing means for water deliveries across eight counties, and why the legal ground beneath the listing is far firmer than the parallel turmoil around the federal Endangered Species Act might suggest. It closes where the more interesting story lives: with the water agencies that chose the opposite path and are demonstrably better off for it.

I. What the Court Actually Decided

The procedural history is a slow march toward a fish. California Trout petitioned the Fish and Game Commission to list the steelhead — Oncorhynchus mykiss, in its below-barrier form — back in June 2021. The Commission advanced it to candidate status; United Water challenged that candidacy decision and lost in October 2023. The Department of Fish and Wildlife then completed its peer-reviewed Status Review recommending the listing, and in April 2024 the Commission voted, unanimously, to list the fish as endangered, the strongest protection state law affords.¹ United Water sued again in May 2025. The June 2026 order disposes of that second suit.

The district made two arguments, and the court rejected both. The first was that the listing lacked “substantial evidence” — that the Commission had leaned on flawed data while ignoring better science, in particular the Cramer Life-Cycle Model, which the district held out as the best available estimate of long-term extinction risk. The court found the Commission had in fact considered the model and reasonably set it aside: Department staff flagged that it used out-of-area and decades-old parameters, displayed “unrealistic levels of resilience,” ran more deterministically than the problem warranted, and — decisively — that the district never supplied the model’s underlying mathematics or source code, so staff could not fully evaluate it.¹ On the dueling population data, the court accepted the agency’s choice of trapping data over noisier snorkel surveys, noted the agency had acknowledged the partial post-drought rebound the district pointed to, and held that data submitted after the administrative record closed was untimely.

What animates the whole ruling is a single principle: courts defer to agency expertise on technical questions. “We will not arbitrate between scientists,” the opinion quotes, and it repeats in several forms the rule that conflicting evidence is not enough — a listing stands unless no reasonable person could have reached it.¹ The district’s second argument, that the Commission had taken too long, fared no worse: the court held the relevant statutory deadlines are directory rather than mandatory, so missing them does not void the decision, and in any event the only remedy for delay — an order to act — was moot now that the Commission had acted. The petition was denied; the Commission was directed to prepare a judgment.^{1 2 3}

The narrow but important takeaway is how United Water lost. It lost on the facts and the science, under a deferential standard — not on any question of what the statute means. That distinction matters enormously for the legal section below.

II. Why a Water District Fights a Fish

To understand the resistance, look at what the listing touches. The Freeman Diversion is a 25-foot structure spanning the Santa Clara River, built in 1991, that pulls an average of roughly 60,000 acre-feet a year out of the river and onto spreading grounds to recharge the Oxnard Plain aquifers; in the wet year of 2023 it diverted a record 148,000 acre-feet.⁴ That recharge is not a luxury. United Water’s conservation operations add on the order of 63,000 acre-feet a year to the basins, the highest groundwater recharge rate in California, and that water both supplies farms and cities and holds back the seawater intrusion that threatens the coastal aquifers.⁵ Every acre-foot the listing requires the district to leave in the river for migrating fish is an acre-foot not spread, not stored, not delivered.

The diversion is also the steelhead’s problem. It and the district’s other structures block the fish from reaching upstream spawning habitat — which is precisely why this is not the district’s first encounter with the species. The steelhead was listed as federally endangered in 1997, and in 2018 a federal court ordered United Water to design and build a long-term fish-passage solution at the Freeman Diversion and release enough water downstream for migration; the Ninth Circuit affirmed in 2020.^{6 7} The passage facility that order contemplates has been projected to cost on the order of $60 million — a bill that ultimately reaches the district’s ratepayers.⁸ Seen against that backdrop, the litigation reads less as a quarrel about fish biology than as a defense of water deliveries and a hedge against the cost of retrofitting a dam — and the district’s repeated reliance on the Cramer Model’s more optimistic projections can be understood as an argument that the river could spare more water than the agencies believed. That is my read of the record, not a motive the district has stated; what the district says is that the agencies ignored its best science.

One clarification worth making, because the two are easily conflated: United Water carried this fight essentially alone. It was the sole petitioner in both suits; the intervenors on the other side were CalTrout, the Center for Biological Diversity, and the Wishtoyo Foundation.¹ The agricultural establishment was aligned but not in the courtroom. The Farm Bureau of Ventura County and the California Farm Bureau opposed the listing vocally during the Commission’s public process — the county bureau’s chief executive questioned whether the historic populations had ever been substantial, and a state bureau analyst warned the listing would “ratchet things up regulatorily for affected water users” and “be used to maximize flows in the rivers and minimize or restrict diversions and groundwater pumping” — and the Association of California Water Agencies questioned the underlying science.^{9 10} But advocacy is not litigation. The record shows alignment of interest, not a documented coalition directing the case. United Water sued because it, uniquely, operates the regulated infrastructure and holds the concrete injury and legal standing that a membership organization does not.

III. What the Listing Means Downstream

The protections reach well beyond Ventura County. The listing covers the steelhead below barriers across its range — from the Santa Maria River, at the Santa Barbara–San Luis Obispo county line, south to the Mexican border — and the agencies tracking it expect effects on water users in San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, Riverside, San Bernardino, and San Diego counties.⁹ For any operator whose diversions, dams, or pumping affect that habitat, the listing converts steelhead recovery from an aspiration into a legal constraint: a prohibition on “take,” consultation with the Department, the prospect of an incidental-take permit, and operating conditions — bypass flows, passage, screening — designed to let the fish migrate and spawn.

The crucial structural point for the region is that this is now a second regime layered on a first. The fish has been federally listed since 1997 and is the subject of a standing federal passage mandate; the new state listing under the California Endangered Species Act runs in parallel, administered by a different agency, on a different legal foundation, enforceable by a different set of plaintiffs. Compliance with one does not satisfy the other. California offers a bridge — a water agency holding a federal incidental-take authorization can ask the Department for a “consistency determination” so the federal terms also satisfy state law — but absent that, dual listing means dual compliance.¹¹ The practical effect on deliveries is therefore not that the water stops, but that the district loses flexibility at the margins, must time and size its diversions around migration windows, and faces a capital bill that flows into the rates its farms and cities pay.

How much new burden the state listing actually adds is a fair question, and the honest answer is: probably less than the alarm around it suggests. The federal regime already does most of the work. The National Marine Fisheries Service biological opinion governing the Freeman Diversion has, by the district’s own accounting in its federal takings suit, cost it at least 49,800 acre-feet of water it would otherwise have diverted, and the 2018 federal court order already compels both the passage facility and downstream migration flows.^{7 12} Because California’s “take” prohibition is narrower than the federal one and does not reach habitat modification as broadly, the state listing’s marginal bite — beyond what the federal biological opinion and court order already require — may be modest. Its larger significance is durability and enforcement: a second, independent legal hook, immune to the federal turmoil described below, and a new set of plaintiffs entitled to enforce it.

None of which is to dismiss the district’s predicament, because the countervailing public interest here is real. The aquifers United Water recharges are in long-term overdraft, and seawater has been pushing inland beneath the southern Oxnard Plain — intrusion that worsened markedly after 2013 and has already rendered some coastal groundwater unusable for farming or drinking.¹³ Every acre-foot the district spreads is partly a wall against that salt. So the dry-year conflict is not simply fish versus farms; it is fish versus a second environmental harm, the salinization of a critical aquifer, and a board can reasonably worry that flows left in the river in a drought are flows not available to hold the ocean back. That tension is genuine, and any durable resolution has to take the intrusion threat as seriously as the extinction threat.

IV. Why the Ground Under This Listing Is Firmer Than It Looks

It would be easy, reading the national news, to assume endangered-species protections are everywhere in retreat. The federal Endangered Species Act is genuinely under pressure — but almost none of that pressure reaches the state listing United Water just lost to, and the reason is the difference in their legal foundations.

The federal Act rests primarily on Congress’s Commerce Clause power, supplemented by the treaty power and authority over federal land.¹⁴ That Commerce Clause footing is the contested one, because many listed species are intrastate and non-commercial, and a more federalism-minded Supreme Court could someday narrow the Act’s reach over them. The more immediate threat is interpretive. The Court’s 2024 decision in Loper Bright Enterprises v. Raimondo ended the Chevron doctrine, under which courts deferred to any reasonable agency reading of an ambiguous statute; agencies must now defend the single best reading.¹⁵ The federal “harm” rule — the long-standing regulation that treats habitat modification as a prohibited take, and the most-used enforcement tool in the Act — was upheld by the Supreme Court in Babbitt v. Sweet Home (1995) partly on the strength of that deference, and in April 2025 the federal wildlife agencies proposed rescinding it, citing the post-Chevron landscape; the proposal drew roughly 357,500 comments.^{16 15} The courts have pushed back in both directions — in March 2026 a federal court struck down a set of Trump-era regulations that had narrowed the Act — and the contest is ongoing.¹⁷ The federal side keeps moving: a Federal Register notice proposes revising the steelhead’s federal critical-habitat designation.¹⁸

Here is the point that matters for California. The state Act does not stand on the Commerce Clause at all. It rests on the state’s police power — the general authority to protect public welfare and natural resources — which needs no commercial hook and is not vulnerable to the theories trimming the federal statute.¹⁹ Loper Bright is a doctrine about federal courts deferring to federal agencies; California never adopted Chevron in the first place, and its courts apply the more flexible Yamaha framework that the steelhead order expressly invoked.¹ And the state’s definition of “take” is narrower than the federal one, reaching the direct acts of hunting, catching, and killing rather than — with only narrow exceptions — habitat modification, so the very federal rule now being rescinded has no clean state analog to attack.¹⁹ The federal Act is a floor, not a ceiling; states may be more protective, and California is. Even if the federal Act were weakened, this listing would stand — which is precisely why state endangered-species law functions as the durable backstop against federal rollback.

The one doctrine that genuinely bridges the federal and state systems is regulatory takings. The Fifth Amendment binds California too, and a water district can argue that mandated bypass flows and water rerouted to a fish passage amount to an uncompensated taking of its water rights — a theory with real precedent in the Tulare and Casitas water cases, though Tulare is widely regarded as an outlier and has been heavily criticized.²⁰ This is not hypothetical for United Water: it has already pressed exactly such a claim — not against the state listing, but against the federal government, seeking compensation for the water the steelhead biological opinion costs it. That suit reached the Federal Circuit and is the subject of a petition for Supreme Court review.¹² No comparable claim has yet been raised against the state listing, but the district has plainly shown it will use the takings door, and that — not the Commerce Clause or Loper Bright — is the avenue through which CESA protections are most plausibly attacked. But California’s defenses are formidable: water rights here are usufructuary, held subject to the constitutional reasonable-use rule and the public-trust doctrine confirmed in the Mono Lake decision, under which the state retains continuing authority to protect the fish and ecology of its waterways.²¹ A diversion that contributes to a species’ extinction is a hard thing to defend as a reasonable use, and a usufructuary right was never a right to the water’s corpus in the first place. Whether the takings door actually opens, in other words, turns on California’s own water-rights doctrines far more than on anything happening at the Supreme Court.

V. The Reactive Trap, and the Agencies That Escaped It

United Water’s path is the expensive one. After two trials it has the constraint anyway, plus the legal bills, plus an adverse record, plus a court controlling the timeline for its $60 million retrofit. The instructive contrast is with the water agencies that treated endangered-species risk as a foreseeable cost and got in front of it.

The closest analog by spirit is the Lower Yuba River Accord. Facing a state order to leave more water in the river for spring-run Chinook and steelhead, the Yuba Water Agency did not litigate to exhaustion; it convened the agencies, fishery groups, and water users and co-developed an alternative. Implemented in 2008, the Accord set science-based, hydrology-flexible instream flows, funded a standing River Management Team with about $565,000 a year for fisheries science, and — by leaning on tools like substituting groundwater in dry years — has kept more water in the river for fish than the state had demanded while still providing roughly 100,000 acre-feet a year on average for fish, cities, and farms. It collected a stack of environmental awards and was extended for another 25 years in 2024–25, the market’s verdict that it works.²² The Yuba agency turned a regulatory threat into a durable agreement; United Water turned the same kind of threat into two lawsuits.

The instrument-level analog is the Santa Clara Valley Habitat Plan — and the name demands a caution, because this is the Santa Clara Valley in the Bay Area, a different watershed entirely from United Water’s Santa Clara River in Ventura County. What makes it the best structural fit is that one of its permittees is a water district. The Santa Clara Valley Water District — Valley Water — joined the County of Santa Clara, San José, Morgan Hill, Gilroy, and the regional transit authority in a combined Habitat Conservation Plan and Natural Community Conservation Plan, a single instrument satisfying both the federal and state Acts. Permits issued in 2013 with a 50-year term, covering 18 listed and at-risk species, and — critically for an operating utility — the plan folds Valley Water’s routine Stream Maintenance Program and its water-supply and flood-protection projects into the same umbrella authorization, so the district does not consult species-by-species every time it stabilizes a bank or clears a channel.²³ The conservation is funded by a tiered development-impact fee rather than loaded onto ratepayers in an emergency, and the results are real: through eleven years of implementation the program had given take coverage to more than 400 projects while conserving roughly 15,080 acres against a 46,920-acre reserve target, with conserved land far outrunning the roughly 2,030 acres of permanent impact it has authorized.²³ Where United Water has open-ended uncertainty, Valley Water bought five decades of operating certainty.

The model is not unique to California. The Edwards Aquifer Habitat Conservation Plan in central Texas, built collaboratively in 2013 by the regional aquifer authority alongside San Antonio and the spring cities, protects endangered species dependent on spring flow and is widely held up as a success — running, by its own permit accounting, at less than a third of its allowable take while maintaining a captive-refugia program for the covered species.²⁴ A major metropolitan water supply secured its own long-term certainty by committing to species protection, rather than by litigating against it.

The common thread is unmistakable. Each of these agencies moved early, negotiated rather than fought, secured flexible and science-based terms instead of court-imposed ones, and spread the cost across the parties that benefit. Each holds, as a result, the one thing United Water still lacks: a predictable future.

VI. What a Proactive United Water Would Have Looked Like

The tools that make the proactive path possible are not exotic; they are written into the same statutes United Water litigated under. Before a species is listed, an agency can enter a Candidate Conservation Agreement with Assurances, trading early conservation for a guarantee against new restrictions if the listing later comes. After listing, a Safe Harbor Agreement rewards habitat improvement, a combined Habitat Conservation Plan and Natural Community Conservation Plan delivers long-horizon certainty, and California’s instream-flow dedication mechanism lets an agency commit water to fish while protecting its underlying right. Every one of these instruments exists to reward acting early — to convert an open-ended liability into a known, fixed commitment.

A version of United Water that had read its own watershed honestly would have looked less like a defendant and more like the Yuba agency. The pieces are already on the ground. The district holds 82,000 acre-feet of surface storage behind Santa Felicia Dam at Lake Piru, an extensive recharge network, and the conveyance to move water where it is needed.^{4 5} The region’s most underused asset is the advanced water-purification facility on the Oxnard Plain, which already produces recycled water and runs at roughly a quarter of its designed capacity — built toward 25 million gallons a day, operating near 6.25.²⁵ Carrying it to full build-out could add on the order of twenty thousand acre-feet a year of drought-proof, river-independent supply, and it would do double duty as groundwater-sustainability compliance and a seawater-intrusion barrier.

None of that is free, and a candid version of this argument has to say so. The purification facility is a reported $75-to-$80-million project, its current 14.4-mgd expansion is financed in part by a $48 million federal WIFIA loan, and — crucially — it belongs to the City of Oxnard, not to United Water, so capturing its yield is a matter of inter-agency partnership and cost-sharing rather than a line item the district can simply approve.²⁶ Recycled water is also not perfectly fungible with river diversions: it differs in location, in cost per acre-foot, and in whether it recharges the basin or is delivered directly, so the “twenty thousand acre-feet” figure is an order-of-magnitude estimate of potential offset, not a guaranteed substitution. And United Water’s own revenue base is narrower than the comparators’: it runs on groundwater pumping charges and water-delivery rates, not the development-impact fees that bankroll the Santa Clara Valley reserve or the metropolitan ratepayer base behind the Edwards plan. The proactive path is cheaper than two lost lawsuits and a court-dictated retrofit — but it is an investment, not a windfall, and pretending otherwise would be its own kind of dishonesty.

It is also fair to ask whether that path was ever fully open. United Water has been entangled with this fish since the 1997 federal listing and under a federal passage order since 2018; by the time the state listing arrived, “get ahead of it” was, for the steelhead specifically, two decades too late. The transferable lesson is therefore less a reproach of United Water than a warning to every district still upstream of a candidate species: the cheap, high-certainty tools — a candidate conservation agreement, an early habitat plan — expire the moment the listing lands. Pair an expanded recycled-water program and additional aquifer storage with a functional-flows regime — water released at the specific moments the fish need it rather than as a blunt year-round minimum — and a negotiated permit that ends the litigation, and the district would have protected its deliveries and the steelhead at once.

That was always the choice. Overturning a listing was never likely — the deferential standard of review makes these cases hard to win once the agency’s science is in order — but the outcome was not preordained, and that is precisely the point: the district had little control over whether the listing stood, and a great deal of control over the terms, the timeline, and the cost of living with it. It spent five years and two trials on the part it could not change and deferred the part it could. The lesson for every other California water board sitting upstream of a declining species is not subtle: endangered-species risk is a financial and operational risk like any other, the law actively rewards the boards that move first, and — for a district whose own aquifer is also under siege from the sea — the worst outcome is to spend down both money and goodwill in a courtroom and arrive at the negotiating table later anyway, with less of each.

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