For decades, the river’s key keepers have ignored massive water losses, allocating their share of the river to Arizona, California, Nevada, and Mexico without deducting what was evaporated.

But 10% can no longer be ignored, say hydrologists, state officials and other Western water experts.

Decades of drought in the west have caused unprecedented low water levels in key reservoirs along the river. Officials in Nevada and Arizona, along with California, have said they should explain how much water is actually flowing into the river.

The challenge is to find a way for California to agree as well.

“It’s very difficult to reach consensus,” said Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University.she thinks that is unlikely the states will reach an agreement Independently, without federal intervention.

Unlike Arizona, California, Nevada, and Mexico, the upper or Upper Basin states of Colorado, New Mexico, Utah, and Wyoming already account for evaporative losses.

Now a federal deadline is looming for the Colorado Valley states to say How to reduce your usage by at least 15% In Arizona, California, and Nevada, accounting for water lost through evaporation has become a new imperative.

One proposal is from Nevada. In states at the edge of the Colorado River, portions of the Colorado River are reduced based on the distance the Colorado River takes to reach the user. The further south the river goes, the more water it loses due to rising temperatures and the longer the water is exposed to the elements.

The Southern Nevada Water Authority estimates that Arizona, Nevada, and California lose approximately 1.5 million acre-feet of water each year to evaporation, transportation, and inefficiency. That’s 50% more than Utah uses in her entire year.

Nevada and Arizona may participate in the plan.

With Lake Mead, an artificial reservoir in Arizona, Nevada, California, and Mexico in its backyard, Nevada stands to lose the least under this plan.

Tom Buschatzke, director of the Arizona Department of Water Resources, called the Nevada Proposal Fair.

“Calculating losses as Nevada proposed is probably the fairest and most consistent with the real physical world,” said Buschatzke. “The farther you go, the greater the loss.”

But crucially, California disagrees. Officials there say the Nevada plan likely runs counter to western water laws.California has rights to the largest share of the Colorado River’s water. Equally important, during periods of water scarcity, water cuts are delayed later than other users based on the so-called river law, a series of overlapping agreements, court decisions, and contracts that determine how the river is shared. am. That higher water right means it has escaped cuts so far.

California water managers say evaporation and system losses should be accounted for based on this existing system. Christopher Harris, executive director of the California Colorado River Commission, wrote in a December letter to federal officials that other approaches “could face considerable legal and technical challenges. ‘ said.

For Arizona, that could mean a huge loss, with some experts saying it could cost the state the Central Arizona Project, a 336-mile (541-kilometer) water system that supplies water from the Colorado River. With supplies dwindling, Phoenix’s drinking water supply could be threatened, he said. To its metropolitan area and Tucson.

Under Nevada’s plan, California would pay an exorbitant price. In addition to using more water from rivers than any other state, its water travels the longest distances. The Imperial Irrigation District of California, the single largest user of Colorado River water, will lose about 19% of its share. Much of the country’s winter vegetables and alfalfa are grown in the area, and Imperial said it would never agree to water cuts in response to evaporative losses.

Tina Shields, water manager for the Imperial Irrigation District, said Arizona and Nevada’s water rights lag behind California’s, and her support for the Southern Nevada Water Authority’s plan is likely due to the loss. He said that sharing is profitable.

“When you have juniors, you know,” Shields said. “You try to share the problem with other users.”

Lower Basin states have long avoided acknowledging these losses, according to John Fleck, a researcher at the University of New Mexico’s Water Resources Program. Water was plentiful and in some states not all legally permitted water was available.

In many cases, the infrastructure (extensive canals, dams, and aqueducts) needed to deliver water did not exist.

“The problem goes back in time… no one ever had to worry about it,” Fleck said.

The complex politics involved also makes the issue somewhat intractable, Fleck said.

“Nobody was willing to take it,” Fleck said. “It’s the same thing in the end. Less water needs to be taken out of the system.”

This article corrects Tom Buschatzke’s title to Director instead of General Manager of the Arizona Department of Water Resources.

Follow Suman Naishadam on Twitter. @Suman Naishadham

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