PHOENIX – Arizona politicians are calling for more cooperation from California in negotiations over Colorado River water supply distribution.

California is in conflict with six other Western states, including Arizona, over a model to cut Colorado River Basin water use.

“Every state needs to come to the table and be part of a basin-wide solution,” Democratic Sen. Mark Kelly said in a press release Tuesday.

“It’s unacceptable for Arizona to do the heavy lifting without meaningful cooperation from California, the largest user of water from the Colorado River.”

Arizona, Nevada, New Mexico, Colorado, Utah and Wyoming sent a letter Monday to the U.S. Bureau of Reclamation that outlines a plan that builds on existing guidelines, deepens water cuts and factors in water that’s lost through evaporation and transportation.

California released a competing proposal the next day. It was based on the elevation of Lake Mead, a key reservoir, but didn’t take into account evaporation losses that would mean big cuts for the Golden State.

“The announcement of the proposed collaborative approach to reach a fair, workable and lasting solution to our water crisis represents a positive step in the right direction, and I’m grateful for Arizona’s leadership on the drought proposal,” Sen. Kyrsten Sinema, an independent, said in a statement.

“Now, it’s time for California to help solve the water crisis and be an equal partner.”

The competing plans came in response to the Bureau of Reclamation asking the states that rely on the Colorado River to detail how they would use between 15% and 30% less water.

All seven states missed a deadline last August.

California has the largest allocation of water among the states that tap the Colorado River. It is also among the last to face water cuts in times of shortage because of its senior water rights.

“While many of the states have worked together to reach an agreement that works for everyone, California refuses to do its part—and in some parts of the state is using more water, not less,” Democratic U.S. Rep. Greg Stanton said in a statement Monday.

“The Bureau of Reclamation must take action on this consensus-driven proposal. We cannot wait any longer.”

Tom Buschatzke, director of the Arizona Department of Water Resources, said Tuesday that water managers across the basin couldn’t reach agreement with California on cuts, even at the broader state level.

“The big issues are what does the priority system mean, what does the junior priority mean and how does that attach to that outcome of who takes what cut?” he said. “That was the issue over the summer, that was the issue over the fall, that’s still the issue.”

JB Hamby, chair of the Colorado River Board of California, said his state’s model is practical, based on voluntary action, and aligns with law governing the river and the hierarchy of water rights.

Failure to reach a consensus carries the risk of having the federal government alone determine how to eventually impose cuts.

The Associated Press contributed to this report.

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