States in the Colorado River Basin are trying their best to propose steep cuts in the water they will use from the river next year, in response to a call from the federal government for immediate, drastic efforts to prevent the major The river’s storage reservoirs reach critically low levels.
The request comes with the Southwest still in the throes of a severe two-decade drought that shows no signs of cessation. And it comes on top of previous, less desperate efforts to hold more water in the two reservoirs, Lake Mead and Lake Powell, including a first-ever deficit declaration last year that cut off water to farmers in Arizona.
The call to save another 4 million acre-feet of water, an amount equivalent to about a third of the Colorado’s current annual flow, is only for 2023. But the long-term outlook for the Colorado is bleak as climate changes change. continues to affect river flow and reduces the likelihood of a series of wet years that could end the drought.
The request for cuts has further exposed the fault lines between the upper basin states of Utah, Colorado, New Mexico and Wyoming and the lower basin states of California, Arizona and Nevada. The states in the upper basin note that they are not using all the water they have been allocated, and that the major cuts will have to come from the states in the lower basin, which consume more than their allotted share.
Aside from the immediate crisis involving the two reservoirs, experts on Western water issues writing Thursday in the journal Science say significant policy changes could stabilize the river in the long term, even if the drought continues. But concessions that “may be unthinkable at the moment” should be implemented quickly, they wrote.
State water managers, irrigation districts, indigenous tribes and others are discussing proposals for major cuts in 2023, to be submitted to the Bureau of Reclamation next month. The cuts are expected to hit the agricultural sector, which uses about three-quarters of Colorado’s water, and the lower watersheds most severely.
“The hard part is that we have taken these incremental steps to reduce water use on the river, a long runway for water users to adapt to the new normal,” said Sarah Porter, director of the Kyl Center for Water Use Policy in the state of Arizona. University. “And now we suddenly have this unprecedented demand to let more water into the system.”
Camille C. Touton, the commissioner of the Bureau of Reclamation, warned that if the negotiations fail, the government could act unilaterally. “We will protect the system,” she said.
“The challenges we see today are unlike anything we’ve seen in our history,” said Ms Touton.
The water level in both reservoirs is historically low, due to declining flows and increasing withdrawals from a river that supplies 40 million people with water and more than 5.5 million hectares of farmland. A major concern is that Lake Powell, behind the Glen Canyon Dam near the Arizona-Utah border, could drop so low next year that it could no longer generate hydroelectric power, or even water through the dam, downstream to the Grand Canyon and Lake Mead, could be affected.
Tina Shields, water manager for the Imperial Irrigation District in Southern California, which has rights to 3.1 million acre-feet of Colorado water, making it the largest user, said it was in talks “to determine options for participation.” to a voluntary program as well as the challenges needed to move forward.”
The need to submit proposals next month “doesn’t make it easy,” she said.
While few details of the talks have been made public across the region, some agricultural users are suggesting fallow fields in return for financial compensation. Depending on the acreage set aside and the amount of water saved, the compensation can run into the billions of dollars. It is not clear where the money would come from.
Chuck Cullom, executive director of the Upper Colorado River Commission, which distributes water among the states in the upper watershed, said there were fundamental differences between the two watersheds. Almost all users of the upper basin get their water directly from the river and its tributaries, so their supply depends on the hydrology or flow from year to year. Users in the lower basin get almost all of their supplies from water stored in Lake Mead. And most of Lake Mead’s water, in turn, comes from Lake Powell.
“Because they rely on storage, their water use patterns are out of sync with hydrology,” said Mr. Collum, referring to the users of the lower basins.
Mr Collum sent a letter to the reclamation office this week outlining the commission’s proposed measures to conserve an unspecified amount of additional water. But he noted that “our water users already have chronic shortages under current conditions” and that “additional efforts to protect critical reservoir elevations should include significant actions directed downstream from Lake Powell,” in the lower watershed.
Maintaining or increasing storage is the goal of the strategies proposed in the Science paper. The researchers said their management approach would consider storage at Mead and Powell together, rather than the current practice of using only the level at Lake Mead to create cuts in the lower basin.
Treating river storage as a whole “opens up a lot more possibilities for better planning,” said Kevin Wheeler, the study’s lead author and a senior research fellow at the Environmental Change Institute at the University of Oxford in Britain.
The researchers used simulations of river flow data from the past two dry decades to see how combinations of reductions in the lower basin and reduced water use growth in the higher basin would affect reservoirs.
By allowing very limited growth in the upper basin and reducing use in the lower basin by about 20 percent, storage levels would be maintained until mid-century, they found, as long as the measures were implemented quickly. .
Long-term reductions would be difficult to accept for users of the lower basin, the researchers noted, as would growth restrictions in the upper basin, where there are plans for projects that would use more water.
“While these concessions of both basins may be unthinkable at this time,” the researchers wrote, “they will be necessary if recent conditions continue.”
