In November 2023, ProPublica and The Desert Sun published an investigation that should change how anyone in Arizona talks about water. Reporters used NASA satellite data and county land records to estimate, field by field, who actually drinks the Colorado River. The answer: in California's Imperial Valley, a majority of the water consumed by farms goes to members of just 20 extended families. In 2022 they used about 387 billion gallons, roughly 1 in every 7 drops that flowed through the entire Lower Basin.

That is the context that's missing every time water gets used as a club against data centers. Not because farming is the villain, but because the orders of magnitude in this debate are wildly out of proportion to where the attention goes.

The Numbers That Reset the Scale

The Imperial Irrigation District holds the single largest entitlement on the Colorado River, 3.1 million acre-feet a year, with 2.6 million acre-feet of senior rights carrying a 1901 priority date that Congress and the U.S. Supreme Court have repeatedly upheld. One irrigation district, established in 1911, has a bigger and older claim to the river than the states of Nevada and Arizona.

Inside that district, one family stands out. Five members of the Abatti family used an estimated 260,000 acre-feet in 2022, about 3 percent of the Colorado River's entire Lower Basin flow. Southern Nevada, which serves over 2 million people in metro Las Vegas, used about 220,000 acre-feet that same year. One extended farming family out-drank the entire Las Vegas valley.

Now put a data center next to that. A 100-megawatt hyperscale facility uses somewhere around 375 acre-feet of water a year, about what a mid-size Phoenix golf course uses, and that figure assumes evaporative cooling, the thirstiest design and the one the Valley effectively stopped approving years ago. The closed-loop and air-cooled systems that actually get built in metro Phoenix today use a fraction of that or none at all, so the comparison below is the worst case for the data center, not the typical one. The Abatti family alone used roughly 690 times that. The whole Imperial Valley delivered about 2.37 million acre-feet to its fields in 2022, the equivalent water footprint of more than 6,000 hundred-megawatt data centers. Arizona does not have, and is not remotely close to having, 6,000 hyperscale data centers.

What the Water Grows

The reflex defense of Imperial Valley farming is that it keeps lettuce, broccoli, and onions on American tables in winter, and some of it does. But ProPublica found that most of the top families use the bulk of their water not on food people eat, but on hay. Sixteen of the top 20 families mostly grow hay, which accounts for an estimated 685,000 acre-feet a year. That is more than four times what San Diego's entire 1.4 million-person water district uses.

A lot of that hay leaves the country. In 2022, about 2 million tons of hay were exported from Southern California ports, half of it to China, with Saudi Arabia taking roughly 200,000 tons of alfalfa. The district gets the river water for free from the Bureau of Reclamation and charges growers about $20 an acre-foot. Cheap, senior, federally subsidized water grows a crop that gets shipped overseas to feed other nations' livestock. As one farm-subsidy researcher put it in the piece, the agencies are "not valuing the water for what it's worth."

This is the part worth sitting with. Critics of data centers talk about evaporative cooling as if it were the frontier of waste in the desert Southwest. The actual frontier is 685,000 acre-feet of forage crop, much of it exported, watered at $20 an acre-foot, by a couple dozen families, under rights no regulator can touch.

Why They Own the River, and Why It Won't Change

The obvious question is why anyone is allowed to flood-irrigate export hay in a drought while cities ration their tap water. The answer is a body of law built to settle the arid West a century ago, and it is working exactly as written.

Western water runs on prior appropriation: first in time, first in right. Whoever put the water to beneficial use first holds the senior claim, and in a shortage senior rights are filled completely before junior users get a single drop. The Imperial Irrigation District's claim traces to diversions that began around 1901, which makes it about as senior as any user on the Lower Colorado. That seniority got frozen into what's called the Law of the River, the stack of compacts, federal acts, contracts, and court decrees that govern the system: the 1922 Compact, the 1928 Boulder Canyon Project Act, California's 1931 Seven Party Agreement that ranked the farm districts ahead of the cities, and the Supreme Court's 1963 decree in Arizona v. California. IID's core entitlement is a "present perfected right," a vested property right that predates and outranks almost everything else on the river.

Two features make this close to impossible to reform. First, these are property rights, not permits. Government cannot simply revoke them. It has to buy them out or condemn them, and condemning water rights triggers Fifth Amendment takings fights nobody wants. That is why the only lever that actually moves water is cash, the $840 per acre-foot conservation payments the district wants federal taxpayers to cover, against alfalfa water worth about $300 an acre-foot.

Second, the doctrine punishes conservation. Under "use it or lose it," a rights holder who doesn't put the full allocation to beneficial use can forfeit the unused portion to the next user in line. So the law actively rewards spreading as much water as possible across the thirstiest reliable crop, which is exactly what alfalfa is. The behavior that looks wasteful from the outside is the rational response to the incentives the rules create. Changing it means rewriting a system locked behind seven states, Mexico, thirty tribes, and Congress, with the most senior holder, California, having the least reason to give anything up. "It is what it is," Gov. Gavin Newsom told The Desert Sun when asked if the arrangement was fair. "It's called senior water rights, and they are well established in law. And they matter."

Why This Matters for Arizona

The point is not that California farmers are bad people. The piece is careful, and so should we be. They farm under rights that are a century old and legally ironclad, and they grow what the market and the law make rational to grow. That is the system working as designed, not anyone cheating.

Arizona, though, sits on the wrong end of that priority stack. To get the Central Arizona Project authorized in 1968, the state agreed that CAP water would be junior to California's senior rights. The bill comes due in a shortage. When the federal government declared Colorado River shortages in 2022 and 2023, Arizona's CAP absorbed the deepest mandatory cuts in the basin while the Imperial Valley, holding senior rights, surrendered nothing it didn't choose to sell. Arizona farms and cities get cut before a single bale of export hay loses its water. That is the backdrop for every Arizona water argument, and it is why aiming the scarcity fight at a data center, the most regulated and least thirsty major new user in the state, gets the problem backward.

The point is proportion. When a data center proposal comes before an Arizona town and the first objection is water, the conversation almost never includes the fact that the single biggest straw in the Colorado River is desert hay, or that one family's alfalfa operation dwarfs the water footprint of every server farm in the state. A 100-megawatt campus that pays industrial tax rates, employs a four-figure operations team, runs increasingly on reclaimed water and closed-loop cooling, and is subject to Arizona's 100-year assured water supply rules gets fought field by field. A 260,000 acre-foot hay operation in a neighboring state does not even enter the discussion.

Arizona also has a structural advantage the Imperial Valley does not. The 1980 Groundwater Management Act and the Active Management Area framework subject every large industrial user, data centers included, to rules that simply do not exist for Imperial's grandfathered farmers. The thing critics fear about data centers, unaccountable water use, is far closer to reality on the agricultural side of the line, and far better governed on the data center side, than the public debate assumes.

The Honest Frame

The river is genuinely overallocated. For a century, allocations assumed about 17.5 million acre-feet would flow each year. The real number, especially since 2000, has been far less, closer to 12.4 million acre-feet. There is not enough water, and hard choices are coming for everyone who draws from the river, including industry.

But honest scarcity math starts with where the water actually goes. ProPublica's methodology was rigorous: satellite evapotranspiration data cross-checked against the district's own crop and soil records, reviewed by independent experts, and matched the district's reported total deliveries to within 0.1 percent. The Imperial Irrigation District declined to release the underlying customer data and then did not dispute the findings. This is about as solid as water-use estimation gets without direct meter access.

So the next time water is the reason a data center can't be discussed on the merits, it's worth asking a simple question: compared to what? Compared to 20 families and a sea of exported hay, a hyperscale campus is a rounding error that happens to come with a tax base, a payroll, and a regulator. The water conversation is worth having. It just has to start with the numbers that actually move the river.

Fact Check

We validated the central claims in the ProPublica/Desert Sun investigation against independent sources before publishing this. The Imperial Irrigation District's 3.1 million acre-foot entitlement and 1901 senior priority date are confirmed by IID's own filings. The Abatti family's 260,000 acre-feet versus Southern Nevada's roughly 220,000 acre-feet was independently reported by the Las Vegas Review-Journal and Las Vegas television coverage. The 2022 hay export figures (2 million tons from Southern California ports, half to China, about 200,000 tons to Saudi Arabia) and the $20 per acre-foot water rate are corroborated across multiple outlets. The Colorado River overallocation (allocations built on roughly 16.5 to 17.5 million acre-feet against actual flows closer to 12.4 million since 2000) is well documented by the Water Education Foundation and federal sources. The legal framework is also well established: prior appropriation, the present perfected rights confirmed in Arizona v. California (1963), and the "use it or lose it" forfeiture rule are basic Western water law, and Arizona's CAP supply was made junior to California's under the 1968 Colorado River Basin Project Act, which is why CAP took the basin's deepest cuts in the 2022 and 2023 shortage declarations. ProPublica issued one correction after publication, on the affiliation of a quoted researcher, not on any of the water-use findings. The investigation holds up.

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