From The Arizona Republic (Ian James):
Arizona, Nevada and Mexico will start taking less water from the Colorado River in January as a hard-fought set of agreements kicks in to reduce the risk of reservoirs falling to critically low levels.
The two U.S. states agreed to leave a portion of their water allotments in Lake Mead under a deal with California called the Lower Basin Drought Contingency Plan, or DCP, which the states’ representatives signed at Hoover Dam in May.
California agreed to contribute water at a lower trigger point if reservoir levels continue to fall. And Mexico agreed under a separate accord to take steps to help prop up Lake Mead, the nation’s largest reservoir near Las Vegas, which now sits 40% full after a nearly 20-year run of mostly dry years.
The agreements, including another deal in the river’s Upper Basin, increase the odds of Western states making it through the next seven years without reservoir levels crashing. But researchers examining the latest climate projections have also warned of the possibility that declines in the river’s flow could force water curtailments in the coming years, and they’ve suggested looking at options to reduce risks.
For the first time since signing the drought contingency deals, representatives of seven states will meet this week at a conference in Las Vegas to talk over their next steps in managing the Colorado River…
Arizona will see a cut of 192,000 acre-feet in water deliveries next year, or 6.9% of its total allotment of 2.8 million acre-feet. Nevada’s share will be reduced by 8,000 acre-feet, while Mexico’s will take 41,000 acre-feet less.
That water will remain in Lake Mead, and will only be recovered in future years once the reservoir rises above an elevation of 1,100 feet. Its level now stands about 15 feet below that threshold.
The cuts under the deal represent 12% of the total water supply for the Central Arizona Project, which delivers water by canal to Phoenix, Tucson and other areas. The agency that manages the canal has said the cuts will reduce deliveries for agriculture by about 15% and eliminate water that would have been available for storing underground and replenishing groundwater at facilities along the CAP Canal…
According to Bureau of Reclamation figures, Arizona and California together conserved 316,000 acre-feet in 2018, and are on track to conserve an estimated 685,800 acre-feet in 2019. Burman said voluntary conservation efforts by the states have helped, and the drought contingency plan has incentivized more conservation…
Arizona’s plan for managing the water cutbacks involves deliveries of “mitigation” water to help lessen the blow for some farmers and other entities, as well as compensation payments for those that contribute water. The payments will be covered with more than $100 million from the state and the Central Arizona Water Conservation District.
Much of the money will go toward paying for water from the Colorado River Indian Tribes and the Gila River Indian Community…
In one study, climate scientists Brad Udall and Jonathan Overpeck used climate models to estimate a business-as-usual scenario of greenhouse gas emissions. They projected that without changes in precipitation, warming will likely cause the Colorado River’s flow to decrease by 35% or more by the end of the century…
In a new report, water researchers Anne Castle and John Fleck warn that the Colorado River’s water supply could decline so much in the next decade that the ability of the four Upper Basin states “to meet their legal obligations to downstream users in Nevada, Arizona, California, and Mexico would be in grave jeopardy.”
Castle and Fleck examined the latest science on projected flows and analyzed the legal framework governing the Colorado River…
Patti Aaron, a spokesperson for the Bureau of Reclamation, responded to the researchers’ findings.
“We applaud a continued focus on the Colorado River, particularly regarding the risks we all are facing going forward,” Aaron said in an email. “We have a solid history in this Basin of finding solutions to complex problems by working together in an open and collaborative way. Reports of this nature help us stay on that path.”
California signed on to the deal, but the state’s Imperial Irrigation District balked at participating.
Imperial holds the single largest share of Colorado River water, which flows to farms producing crops such as alfalfa, broccoli and Brussels sprouts. Imperial’s officials have called for the state and federal governments to urgently address a worsening environmental crisis at the Salton Sea, which is shrinking and exposing dry lake bed that sends dust blowing into surrounding communities.
The sea has been shrinking more rapidly under a 2003 deal that is transferring water from the Imperial Valley to growing urban areas in San Diego County and the Coachella Valley.
In October, the Imperial Irrigation District’s board members voted unanimously to declare an emergency at the Salton Sea, pressing for California officials to break through years of wrangling and red tape to get working on dust-control and habitat projects along the retreating shores.
Last month, the IID board adopted a resolution laying out parameters for IID’s involvement in future Colorado River negotiations. They said in the resolution that “the linkage between the Colorado River and the Salton Sea is inextricable.”
Burman, who is scheduled to speak, said the drought contingency plan has laid a foundation that will help the states and other parties work through their next steps.
“Our history on the Colorado River is making improvements and incremental progress as we go,” Burman said. “It’s important that we’re out there talking about the challenges. It’s important that we’re out there talking about possible solutions.”