The Colorado River’s reservoirs are dangerously declining. States must offer discounts.

States in the Colorado River Basin are scrambling to propose sharp cuts to the water they will use from the river next year, responding to a call from the federal government for immediate drastic efforts to prevent the river’s major storage reservoirs from reaching too low a level. levels.

The demand comes as the southwest remains in the grip of a severe two-decade drought and shows no signs of abating. It comes on top of earlier, less desperate efforts, to conserve more water in the two reservoirs, Lake Mead and Lake Powell, including The first ever shortage announcement Last year it cut water to farmers in Arizona.

The call to conserve up to an additional 4 million acres of water, an amount equal to about a third of Colorado’s current annual flow, is only for 2023. But the long-term outlook for Colorado is bleak, as climate change continues to affect river runoff and reduces the likelihood of runoff in the river. The occurrence of a series of wet years that can end the drought.

The request for cuts has further exposed fault lines between the upper basin states of Utah, Colorado, New Mexico and Wyoming and the lower basin states of California, Arizona and Nevada. Upper-basin states indicate that they are not using all of their allocated water, and that the most significant reductions should come from lower-basin states, which use more than their allotted quota.

Regardless of the current crisis related to the two reservoirs, experts in western water issues He writes Thursday in the science magazine He says major policy changes could stabilize the river in the long run, even if the drought continues. But they wrote that concessions that “might be out of the question for the time being” must be implemented soon.

Water managers from states, irrigation districts, indigenous tribes and others are discussing proposals for steep cuts in 2023, which should be submitted to the Bureau of Reclamation next month. The cuts are expected to fall dramatically on agriculture, which uses about three-quarters of Colorado’s water, and in lower basin states.

“The challenging thing is that we have taken these additional steps toward reducing water use on the river, which is 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 Arizona. University. “And now we suddenly have this unprecedented demand to leave more water in the system.”

Calling for the cuts at a Senate hearing last month, Camille C. Totton, commissioner of the Office of Reclamation, warned that if negotiations failed, the government could act unilaterally. “We will protect the system,” she said.

“The challenges we see today are unlike anything we have seen in our history,” Ms Totton said.

Levels in the two reservoirs were at historic lows, as a result of reduced flows and increased withdrawals from a river that provides water to 40 million people and more than 5.5 million acres of farmland. The main concern is that Lake Powell, behind the Glen Canyon Dam near the Arizona-Utah border, could decline next year to the point that it can no longer generate hydroelectric power, and even water through the dam, downstream to the Grand Canyon and Lake Mead, can be affected.

Tina Shields, Water Director at Imperial irrigation district In Southern California, which holds rights to 3.1 million acres of Colorado water, making it the largest user, it said it was in talks to “identify opportunities to participate in a volunteer program as well as challenges needed moving forward.”

The need to submit proposals by next month “doesn’t make it easy,” she said.

While few details of the talks have been announced across the region, some agricultural users are suggesting resting the fields, in exchange for monetary compensation. Depending on the irrigated area and the amount of water conserved, compensation can run into billions of dollars. It is not clear where the money will come from.

There are key differences between the two basins, said Chuck Cullum, executive director of the Upper Colorado River Commission, which allocates water between the states of the upper basin. Almost all upper basin users get their water directly from the river and its tributaries, so their supply is subject to hydrologic flow or flow from year to year. Users of low-lying basins get nearly all of their supply from the water stored in Lake Mead. 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 users of the lower basin.

Mr Collum sent a letter to the Office of Reclamation this week outlining the commission’s proposed actions to conserve an unspecified amount of additional water. But he noted that “our water users are already chronically short under current conditions” and that “additional efforts to protect critical reservoir elevations should include important actions focused on the Lake Powell Riverbed” in the lower basin.

Maintaining or increasing storage is the goal of the strategies suggested in the science paper. The researchers said their management approach would consider storage in Mead and Powell together, rather than the current practice, where the level in Lake Mead is used only to make reductions in the lower basin.

Addressing river storage as a whole “opens up a lot of possibilities for better planning,” said Kevin Wheeler, lead author of the study and senior research fellow at the Institute for Environmental Change at Oxford University in Britain.

The researchers used simulations incorporating river flow data over the past two dry decades to see how combinations of reductions in the lower basin and decreased growth in water use in the upper basin could affect the reservoirs.

They found that allowing very limited growth in the upper basin and reducing use by about 20 percent in the lower basin would maintain stock levels until mid-century, as long as measures are implemented soon.

The researchers note that long-term reductions will be difficult for users of lower basins to accept, as well as growth limitations in the upper basin, where there are plans for projects that will use more water.

“Although these concessions from both basins may currently be unimaginable, they would be necessary if the latter conditions persist,” the researchers wrote.

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