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Water Rights/Case Library

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National Audubon Society v. Superior Court, 33 Cal. 3d 419 (1983)

Why this matters: Los Angeles had a valid, vested water right and was draining a lake with it. California held that the public trustpublic trust doctrineThe state holds navigable waters and the land beneath them for everyone, and cannot sign that away. Wisconsin's version is written into the state constitution and is among the strongest in the country. never goes away, so the state can reopen an allocation it approved decades earlier. “Vested right” turns out to mean less than owners assume. That principle has teeth in Wisconsin too.

Doctrine: Public trustpublic trust doctrineThe state holds navigable waters and the land beneath them for everyone, and cannot sign that away. Wisconsin's version is written into the state constitution and is among the strongest in the country., prior appropriationprior appropriationThe western US rule. Whoever first took water and put it to use has the strongest claim, no matter where their land sits. The shorthand is "first in time, first in right.", reallocation

Case name and citation

National Audubon Society v. Superior Court, 33 Cal. 3d 419, 658 P.2d 709, 189 Cal. Rptr. 346 (1983), cert. denied, 464 U.S. 977 (1983). Known universally as the Mono Lake case.

Court and year

Supreme Court of California. Decided February 17, 1983.

One-line holding

The public trust doctrine and the appropriativeprior appropriationThe western US rule. Whoever first took water and put it to use has the strongest claim, no matter where their land sits. The shorthand is "first in time, first in right." water rights system form a single integrated body of California water law, the state retains continuing supervisory authority over navigablenavigable in factWisconsin's test for whether a waterway is public. Roughly: can a small recreational boat float on it on a regularly recurring basis. A lot of modest creeks qualify. waters, no party can acquire a vested right to appropriate water in a manner harmful to public trust interests, and the state must reconsider allocations made without considering the trust.

Facts

Mono Lake sits east of the Sierra Nevada, an ancient saline lake with no outlet. Its tufa towers, brine shrimp, and enormous migratory bird populations depend on a fragile salinity balance.

Starting in 1941, the Los Angeles Department of Water and Power diverted 4 of the 5 freshwater streams feeding the lake, sending the water 350 miles south through the Los Angeles Aqueduct.

The permits were valid. The State Water Board issued them under California’s appropriation system. At the time, the Board had no specific statutory authority to consider environmental values, and it did not consider them.

Over 40 years the lake dropped roughly 45 vertical feet. Its volume halved. Salinity doubled, threatening the brine shrimp that feed the birds. A land bridge emerged to Negit Island, exposing a major California gull nesting colony to coyotes.

The National Audubon Society sued in 1979, arguing the diversionsdiversionMoving water out of the Great Lakes basin. The Compact bans new ones except in a few narrow cases. violated the public trust.

The 2 sides staked out maximalist positions. Plaintiffs argued the public trust is antecedent to all appropriative rights, which would imply that most California water rights had been acquired and used unlawfully. The DWP argued the public trust had been absorbed into the appropriation system and quietly disappeared, so a Board license conveys a perpetual vested right to take water without regard to consequences.

Is the public trust doctrine subsumed within the appropriative water rights system, or does it operate as an independent limit that allows the state to reconsider water rights it has already granted?

Holding and reasoning

The court rejected both extremes and built a third position.

California water law “is an integration including both the public trust doctrine and the board-administered appropriative rights system.” Neither one occupies the field.

From that integration the court drew several rules.

The state as sovereign retains continuing supervisory control over navigablenavigable in factWisconsin's test for whether a waterway is public. Roughly: can a small recreational boat float on it on a regularly recurring basis. A lot of modest creeks qualify. waters and the lands beneath them. That principle “prevents any party from acquiring a vested right to appropriate water in a manner harmful to the interests protected by the public trust.”

The trust covers ecological and recreational values, not just navigation, commerce, and fishing.

The trust protects navigable waters from harm caused by diverting non-navigable tributaries. That was essential here, since the streams LADWP diverted are not themselves navigable. Mono Lake is.

Parties acquiring rights in trust property hold them subject to the trust. The state may revoke previously granted rights, and only rarely can anyone acquire a right free of trust restrictions.

The state has “an affirmative duty to take the public trust into account in the planning and allocation of water resources, and to protect public trust uses whenever feasible.”

Critically, the court declined to hold the diversionsdiversionMoving water out of the Great Lakes basin. The Compact bans new ones except in a few narrow cases. unlawful per se. It adopted a balancing approach. Los Angeles’s domestic water needs get weighed against Mono Lake’s ecological needs, and harm to the trust must be minimized where feasible.

Because the impact on trust uses had never been considered, the court held that “an objective study and reconsideration of the water rights in the Mono Basin is long overdue.” The Board and the courts have concurrent jurisdiction to conduct it.

Why it matters

The best story in American water law, and the most unsettling holding for anyone who thinks a permit is permanent.

Los Angeles did everything right procedurally. It applied, it received licenses, it built infrastructure, it relied for 40 years. And the California Supreme Court held that none of that bought immunity, because the state never had the power to give away the trust in the first place.

The remedy was real, not symbolic. In subsequent proceedings the State Water Board ordered LADWP to sharply reduce diversions until the lake rises to a target elevation, a recovery still underway more than 40 years later. Mono Lake’s level remains below the target as of 2026.

The doctrinal move worth understanding is the one about tributaries. Extending trust protection upstream to non-navigable feeder streams is what gives the doctrine practical reach, because diversions rarely happen on the navigable water body itself.

Compare Illinois Central (1892), where the trust blocked a conveyance of the lakebed itself. See 1892-illinois-central-railroad-v-illinois.md. Mono Lake extends the same logic to water use far from the trust resource.

The Wisconsin parallel is direct. When the Wisconsin Supreme Court held in Lake Beulah (2011) that the DNR has a public trust duty to consider whether a groundwater well may harm surface waters, it was making the same structural move: the trust reaches the activity that harms the resource, wherever that activity happens. See 2011-lake-beulah-v-dnr.md.

What it means for a landowner today

California law does not govern a Wisconsin parcel. The principle it illustrates does, in Wisconsin’s own version.

Practical translation:

  • A permit is a snapshot of a regulator’s judgment at one moment. In a strong public trust state, it is not a guarantee against future conditions.
  • Wisconsin’s trust is constitutional, grounded in article IX, section 1. The legislature cannot simply repeal it, which the Wisconsin Supreme Court effectively confirmed in Clean Wisconsin (2021). See 2021-clean-wisconsin-v-dnr.md.
  • If a parcel’s value depends on a large water withdrawal, price in the possibility that the withdrawal gets conditioned or reduced later.
  • The corollary is protective. The same doctrine that could constrain your use also constrains the large user upstream of you.

What to verify: whether any existing approval on the parcel carries conditions, monitoring requirements, or sunset provisions, and whether the water body is subject to any restoration order, total maximum daily load, or special designation. Who verifies: the Wisconsin DNR and a Wisconsin real estate attorney.

Subsequent history / is it still good law

Good law as of July 2026, foundational in California, and influential well beyond it. The U.S. Supreme Court denied certiorari in 1983.

The Mono Lake proceedings continued for years. State Water Board Decision 1631, issued in 1994, amended LADWP’s licenses to require the lake to reach and maintain an elevation of 6,392 feet above sea level, restricting diversions until it does. Recovery has been slower than projected, and the Board has revisited the framework since. [UNVERIFIED] as to the lake’s exact current elevation and the status of the most recent Board proceedings; confirm with the State Water Board before relying on specifics.

The doctrine has spread unevenly. Some states have adopted Mono Lake’s reasoning, others have declined. Attempts to extend the public trust to the atmosphere in climate litigation have largely failed in federal court.

Sources

Research demo, not legal advice. Facts current as of July 2026. Water law is state-specific and moves quickly, so confirm anything you plan to act on with a licensed attorney and the relevant state agency.