Nevada's Colorado River lawsuit is right on the merits and beside the point

Lake Mead fell to its lowest level since the reservoir was first filled in the 1930s earlier this month, a marker that made the timing of Nevada's newest lawsuit against the federal government feel less like litigation strategy and more like arithmetic. On August 24, the state, joined by the Colorado River Commission of Nevada and the Southern Nevada Water Authority, sued the Department of the Interior in federal court, asking a judge to throw out the agency's newly finalized rules for sharing what is left of the Colorado River. The suit does not dispute that the river is shrinking. It disputes who has to shrink with it.

A record low, a lawsuit filed within days

On August 21, Interior Secretary Doug Burgum signed a Record of Decision and a set of 2027-2028 Operating Guidelines for the Colorado River, the product of a multi-year federal review triggered by the looming expiration of the rules that have governed Lake Mead and Lake Powell since 2007. The new guidelines establish a 10-year "Decision Framework" running through 2036 and require Arizona, California and Nevada — the river's Lower Basin states — to collectively cut their annual consumption by 1.25 million acre-feet in each of the next two years: 760,000 acre-feet from Arizona, 440,000 from California, and 50,000 from Nevada. Colorado, Utah, New Mexico and Wyoming, the Upper Basin states, face no mandatory reductions at all, only voluntary conservation targets.

Nevada filed suit three days later. Governor Joe Lombardo's announcement of the lawsuit did not mince language: "Under the proposed plan issued by the Department of the Interior, southern Nevada could lose more than 70 percent of its already meager Colorado River allocation while the Upper Basin states of Colorado, Utah, New Mexico, and Wyoming are not required to contribute a drop." The suit, filed in federal court in Nevada, asks the court to set aside the Record of Decision and block its implementation, arguing Interior violated the National Environmental Policy Act, the Administrative Procedure Act, and what water lawyers call the Law of the River — the accumulated body of compacts, court decrees and federal statutes governing the basin.

The math behind the complaint

Nevada's underlying grievance is proportional, not just absolute. The state's base annual allocation, 300,000 acre-feet, is already the smallest of any Colorado River state — a fraction of Arizona's 2.8 million or California's 4.4 million acre-feet. Yet under the scenarios the lawsuit cites, further reductions tied to the new framework could leave the Las Vegas metropolitan area with as little as 86,500 acre-feet a year by 2029, down from roughly 212,500 acre-feet used in 2024. John Entsminger, the Southern Nevada Water Authority's general manager, called that trajectory "entirely unrealistic" and pointed to a conservation record that the region argues should count for something: Southern Nevada has cut its Colorado River consumption by roughly 40 percent over the past 25 years even as the area added more than 800,000 residents, through measures like turf-removal rebates and recycling nearly all indoor water use.

"The Department of the Interior can't roll Nevada and solve the entire Colorado River shortage on the backs of the Lower Basin states — we are prepared to fight for as long as it takes." — Nevada Governor Joe Lombardo

Arizona has not yet joined the suit but has signaled it is unhappy; water officials there have called the plan a source of "significant additional level of uncertainty," and the state is weighing its own options. California, the largest single user on the river, has been more accommodating of the near-term cuts, though it has not committed to the longer-term reductions embedded in the 10-year framework.

A compact built for a river that no longer exists

The asymmetry Nevada is suing over did not originate with Secretary Burgum. It is baked into the 1922 Colorado River Compact, which split the river's flow evenly on paper — 7.5 million acre-feet a year to each basin — using measurements taken during an unusually wet stretch of the early 20th century. Negotiators assumed something like 17 to 20 million acre-feet flowed through the system annually. The actual long-term average is closer to 12 million acre-feet, and shrinking; this past winter produced the worst snowpack on record across the basin, and by early August, combined storage at Lakes Mead and Powell had fallen to its lowest point in roughly seven decades, with Mead itself dropping below its previous 2022 record low.

The Upper Basin states never fully built out the infrastructure to use their full allocation, which is one reason they can absorb a bad water year without a mandatory federal order forcing their hand; their obligation under the compact is to avoid depleting storage below certain thresholds over rolling periods, not to stay under a hard annual cap the way the heavily built-out Lower Basin does. That legal structure made sense when the difference between paper allocations and real water was smaller. It looks very different when the river running through the compact's original math has essentially stopped existing, and the burden of accommodating that fact falls almost entirely on the three states — Arizona, California and Nevada — whose farms, suburbs and casino floors were built assuming a Colorado River that the 1920s never actually had.

What a courtroom win would not fix

Nevada's procedural claims may well have merit. Interior spent more than three years and reviewed six operational alternatives before settling on the current framework, according to its own account of the process, precisely because the seven basin states could not reach the kind of unanimous consensus that shielded the 2007 guidelines and the 2019 drought contingency plan from serious legal challenge. A framework imposed without that consensus is more exposed to arguments that the agency skipped required environmental or economic review — arguments a federal judge in Nevada may credit.

But even a full vacatur of the Record of Decision sends the problem back to Interior, not away. The river will still be delivering roughly 12 million acre-feet where the compact imagines 15 million or more. The Upper Basin states will still lack a legal or political mechanism that forces mandatory cuts on four separate, less populous states in the way it is comparatively simple to impose them on three states whose water use is concentrated in a handful of urban and agricultural authorities. And the deeper argument the lawsuit sidesteps — that a 104-year-old compact built on data from one of the wettest periods in over a millennium of Colorado River history has no honest way to allocate a permanently smaller river — will still be sitting there, unresolved, waiting for the next Record of Decision and the next lawsuit.

• Interior's August 21 order requires Arizona, California and Nevada to cut a combined 1.25 million acre-feet annually in 2027-2028, while Colorado, Utah, New Mexico and Wyoming face no mandatory reductions.
• Nevada's suit, filed August 24, argues the state could lose more than 70 percent of its 300,000-acre-foot allocation and cites Administrative Procedure Act and NEPA violations.
• Combined storage at Lakes Mead and Powell reached its lowest level in roughly 70 years this summer, following the worst snowpack on record across the basin.

What Nevada is really asking a federal court to referee is not primarily an environmental-review technicality. It is a century-old bet about how much water the West actually has, made by negotiators who had every incentive to guess high and no way of knowing they were wrong. The lawsuit may well win Nevada a better outcome than the one Interior just handed down. It will not produce a Colorado River large enough to make the underlying argument go away.