A crew harvests a field of baby green lettuce in the Gila Valley in Yuma, Ariz. The harvester cuts baby greens with a large bandsaw that’s continuously sanitized.

 Randy Hoeft, Yuma Sun

Yuma-area farmers are fighting a proposed set of Colorado River water use curbs, saying they favor urban users in Phoenix and Tucson even though the farmers have higher-priority rights to the water.

The disagreement means puts Arizona’s two biggest Colorado River water using sectors — big cities and farms — squarely at odds. And it’s happening at the same time Arizona and five other Colorado River Basin states are squaring off against California over how to shave millions of acre feet a year off total diversions of water from the overallocated, depleted river.

An attorney for the Yuma farmers, Wade Noble, wrote Arizona state water chief Tom Buschatzke recently that the farmers don’t agree with a number of key points in a proposal for river water cuts made by Arizona and all the other seven river basin states except California. Among them are how evaporation losses on the river will be counted against the farms’ legal access to river water, whether river water should be allocated to cities for “human health and safety” purposes and over cities’ ability to access river water they’ve temporarily stored in Lake Mead to prop up its water level.

In an interview, Noble said his biggest concern is that the six-state proposal appears to take hundreds of thousands of acre feet of river water Yuma irrigation districts have long held rights to and essentially turn it over to Central Arizona cities that legally have lower priorities for the water.

The large majority of crop acreage in Yuma has what’s called Priority 3 water rights to the river, whereas the Central Arizona Project has Priority 4 rights, the lowest available, he said.

The Yuma-area irrigation districts have rights to roughly 800,000 to 900,000 acre feet a year of river water. The CAP has historically had rights to at least 1.5 million acre feet a year of water. It’s cut its share to around 1 million acre feet annually in the past few years in response to earlier drought plans aimed at keeping Lake Mead from collapsing.

But taking too much water rights from river farmers could trigger a collapse of the agricultural industry there that grows winter vegetables sold across the U.S., Noble said. For one, about 95% of the country’s winter lettuce crop comes from Yuma, various experts have said.

“The industry can’t continue to function if you take out more than a certain percentage of the water,” he said. “I’m told you could take out 25% and keep the industry going. I don’t think people in Yuma County accept that. If you take it down, you take it down. The industry collapses.

“It’s not like you keep planting fewer veggies in the garden. It’s that the garden at some point dies.”

Buschatzke, director of the Arizona Department of Water Resources, declined last week to comment on Noble’s letter. It was written in late February on behalf of a coalition of Yuma-area irrigation districts.

But the farm-city split over water use curbs troubles Terry Goddard, president of the Central Arizona Project’s governing board. He sees a need for unity in the face of what could be a protracted struggle with California over who should bear the brunt of river water use cuts.

A proposal from the six basin states besides California relies heavily on accounting for evaporation losses in the river and reservoirs in the Lower Colorado River Basin to determine how big of a cut each state would take. Because California has easily the largest share of river water rights, it’s presumed to account for the largest share of total evaporation. So the large majority of this plan’s cuts would hit California.

The other proposal, from California, would divvy up cuts based on which users have the highest priority, under water rights allocations dating back a century or more. Since the Central Arizona Project — which delivers drinking water to Tucson and Phoenix — ranks last on the priority list for river water during shortages, the bulk of the California plan’s cuts would fall on Arizona.

In that context, Goddard said that even though he could argue with the points made in it, Noble’s letter is a good starting point for discussion.

“We have to have the discussion as part of a unified Arizona effort,” Goddard said. “We waited way too long for a statewide discussion on what is Arizona’s interest as a whole. If we get split up, we are not going to be significant factor (in the negotiations).”

“Arizona has certainly not the strongest position on the river,” he said. “We need to be unified. I think we have to resolve it among ourselves: This is what Arizona can do and what Arizona can’t do.”

Environmental impact statement pending

The U.S. Bureau of Reclamation is reviewing both sides’ proposals as it prepares a supplemental environmental impact statement onh how to carve up the river’s dwindling supplies.

It’s expected to release a draft statement this spring that will lay out its view on how cuts should be made. It has pushed for cuts of 2 million to 4 million acre feet annually in total river water use. The bureau has also said it would prefer for the states to settle on a negotiated solution but that it’s prepared to lay down its own plan if the states can’t agree.

Noble’s letter makes several points:

— The six-state proposal counts evaporation losses connected to farms based on what’s known as their “consumptive use.” That’s the net amount of water that a farm uses after accounting for the water that’s placed onto crops but rather than irrigating the crops stays above ground and flows back to the river.

But basing evaporation loss cuts on consumptive use takes a huge financial toll on farmers compared to what would happen if those cuts came strictly from a farmer’s legal water right “entitlement,” which is a much larger total amount of water, Noble said.

— Senior water rights holders in the Yuma area face water losses during shortages even as water users with junior water rights are able to remove water they left in Lake Mead years earlier under a program called Intentionally Created Surplus. This gives the junior water rights holders an ultimate “super priority” to that water compared to the junior rights holders, he said.

“As a result, water lawfully and contractually committed to senior priority users would not be delivered, and junior priority users, as a result of an unlawful super priority … would take water wrongfully denied to senior priority entitlement and water rights holders,” Noble said.

— The California plan, carried to its logical extension, could wipe out deliveries to the CAP due to its low priority. But some California-based water officials have said they would be open to insuring that CAP users including large cities such as Tucson would still gain access to enough river water to protect an undefined level of “human health and safety.”

In his letter, however, Noble said Yuma-area water rights holders “object and challenge” the use of human health and safety as a criteria to be used by either the bureau or the State of Arizona.

“’Human health and safety’ is not a legally recognized water right in Arizona and should not be given special consideration in the decision making process of the State of Arizona or the Bureau of Reclamation in determining how available Colorado River water should be allocated,” he wrote.

It should be treated with the same priority level a water user has under the user’s existing entitlement, he wrote.

Noble said the Yuma farmers also don’t support the California plan, which he says unfairly favors water users in that state compared to those in the Yuma area. He declined to speculate as to whether the farmers would sue to overturn whatever plan is approved if it wasn’t to their liking.

“We have no plan to litigate at this point. Is it possible? It’s certainly possible, if they wiped out all the priority 3 water in Yuma County agriculture, that would take away over 400,000 acre feet of 800 to 900,000 acre feet.”

He, like other Arizona water users, said he was encouraged by the recent announcement by Reclamation commissioner Camille Touton that the bureau will spend $250 million to pay Lower Basin water users to use less water, in an effort to save enough water to raise Lake Mead 10 feet this year.

Hopefully, when the bureau publishes its draft environmental review of the various water use proposals, “There will be some shaping of the plan that recognizes what the realities of water use in the basin, particularly in the Lower Basin,” Noble said.

When some people talk about opening up and possibly changing the Law of the River — a century-old collection of laws, regulations, court cases and other legal processes that govern the basin’s water use — “I think Reclamation will be very careful of doing that,” Noble said. “When you talk about wiping out part of the national food supply … that’s what I call reality.”

A blanket of crops covers the ground of the Imperial Valley in southern California, a patchwork of vibrant greens given life by the Colorado River in a landscape bleached by the desert sun. But as a decades-long drought desiccates the U.S. West and the once-mighty river dwindles, questions are being asked about why a handful of farmers are allowed to take as much water as all of Nevada and Arizona combined.

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Contact Tony Davis at 520-349-0350 or tdavis@tucson.com. Follow Davis on Twitter@tonydavis987.