Bracing for an ever-growing gap between supply and demand of Colorado River water, three Southwestern states today unveiled an agreement that would cut California’s portion by about 10% in most years.
California, Nevada and Arizona submitted their plan to the federal government, which is weighing how to manage the drought-plagued river after 2026, when another historic deal expires. The decision will shape long-term management of a vital water source for 40 million people, including 30 tribal nations and 5.5 million acres of agriculture.
For more than a century, the river’s water has been allocated among seven states, tribes and Mexico through a collection of deals, acts, treaties and legal decisions known as the Law of the River. But a decades-long mega-drought, culminating in the driest 23-year period in more than a century, has shriveled the river’s already over-allocated flows.
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Despite recent improvements after storms, Lake Mead and Lake Powell, the basin’s major reservoirs, remain “historically low, and long-term conservation measures will still be necessary,” the U.S. Bureau of Reclamation reported Tuesday.
California takes the biggest share of Colorado River water, with a yearly allocation of 4.4 million acre-feet. And Imperial Valley growers are, by far, California’s biggest user — allocated 3.1 million acre-feet a year, or more than two-thirds of the state’s supply, to irrigate half a million acres of alfalfa, winter vegetables and other crops via the Imperial Irrigation District.
The Metropolitan Water District, which provides water for 19 million Southern Californians, is another large user, typically receiving about 1 million acre-feet every year, according to Bill Hasencamp, the district’s manager of Colorado River resources. (An acre-foot is enough to supply three Southern California households for a year.)
“It’s a big change that we will have to adapt to as a state,” Hasencamp said, adding “it’s 10%, so we should be able to tighten up our belt 10%.”
In the new proposal, the three states agreed to collectively cut their water use when levels dip below 69% capacity, ramping up to at least 1.5 million acre-feet a year below 58% of capacity. That’s about 17% of their total allocations, enough to supply 3.75 million Southern California households for a year. Over the past ten years, the reservoirs have largely stayed below that threshold. If the system dips lower than 38% of capacity, any additional cuts up to 3.9 million acre-feet would be shared equally between the Upper and Lower Basin states.
Arizona would shoulder much of the burden by cutting use about 27% in most years. Nevada would cut back by about 17%, and Mexico — if it agrees — by 250,000 acre-feet, or about 17% of the 1.5 million acre-feet it’s entitled to under an agreement with the U.S.
The three states also proposed a new way to trigger the cuts — based on seven reservoirs across the basin, not just Lake Mead, Hasencamp said.
John Entsminger, general manager of the Southern Nevada Water Authority, said at a briefing today that the aim is to avoid suspicions of states manipulating the system. Withdrawing water from Lake Mead or holding it in Upper Basin reservoirs could result in massive changes in water releases.
The current system “has led to a number of conflicts between the states since it was implemented in 2007 because literally one foot of elevation difference in Lake Mead or Lake Powell can result in more or less water being released,” Entsminger said. “There were constant suspicions about states gaming the system, being able to manipulate those elevations. And we believe what we are presenting today will remove the ability for this, any even suspicion.”






















