#California, #Arizona and #Nevada in talks on new plan to save #ColoradoRiver water — The Los Angeles Times #COriver #aridification

Brad Udall: Here’s the latest version of my 4-Panel plot thru Water Year (Oct-Sep) of 2021 of the Colorado River big reservoirs, natural flows, precipitation, and temperature. Data (PRISM) goes back or 1906 (or 1935 for reservoirs.) This updates previous work with
@GreatLakesPeck.

From The Los Angeles Times (Ian James):

Two and a half years after signing a deal aimed at averting a damaging crisis along the Colorado River, water officials from California, Arizona and Nevada are discussing plans to take even less water from the shrinking river and leave it in Lake Mead in an effort to prevent the reservoir from falling to dangerously low levels.

Representatives of water agencies from the three states said they are firming up the details of a deal that would leave an additional 500,000 acre-feet of water in the reservoir next year, and the same amount again in 2023 — about double the quantity of water used annually by Las Vegas and the rest of southern Nevada.

For California, the deal would mean participating in water reductions prior to Lake Mead reaching levels that would otherwise trigger mandatory cuts.

The talks took on urgency this summer after federal projections showed growing risks of Lake Mead falling to critically low levels, despite plans for mandatory cutbacks throughout the Southwest that the states agreed to in 2019.

With the reservoir in a first-ever shortage and those cuts still insufficient, water management officials settled on a goal of together leaving half a million acre-feet of additional water in the reservoir instead of sending it flowing to farms, cities and tribal lands. The stored water would be roughly as much as 1.5 million average single-family households use in a year.

“We’ve got to stabilize the lake with this plan,” said Tom Buschatzke, director of the Arizona Department of Water Resources. He said representatives of California, Arizona and Nevada developed the framework of the deal within about two months after they saw projections showing growing risks of Lake Mead dropping to lows that would trigger much larger water reductions in all three states.

“I think coming together in that short a period of time is indicative of urgency we’re feeling to do more,” Buschatzke said. “If the lake keeps falling, cuts are going to be deeper and deeper and deeper. So I think it’s indicative of the risks.”

The deal would nearly double the reductions in planned water deliveries next year among the three states beyond those already planned under the 2019 agreement, called the Drought Contingency Plan. This new proposal, dubbed the 500+ Plan, would partially involve securing money to pay some water users to voluntarily relinquish water.

The water would come from various sources, including farmers who would be paid for leaving portions of their land dry, tribes that would contribute water supplies, and water agencies that would leave some water in Lake Mead instead of taking it out as planned.

Negotiations on the details are continuing, and officials from California and Arizona said they hope to have the overarching agreement ready to be signed next month at [the Colorado River Water Users Association] conference in Las Vegas.

Arizona has pledged $40 million toward the deal. Board members of the Southern Nevada Water Authority are scheduled to consider approving up to $20 million in contributions this week.

The board of the Metropolitan Water District of Southern California is scheduled to consider the proposed agreement next month…

If the details of the proposal come together as planned, 500,000 acre-feet of water over two years would translate into water levels about 16 feet higher in Lake Mead…

For now, the talks have focused on lining up funds and water for two years. But Buschatzke said it’s intended to be a five-year plan, lasting until the current agreement expires at the end of 2026, by which time the states will need to have negotiated new rules for dealing with shortages.

If the winter were to bring heavy snow to the Rocky Mountains, it could still help ease the shortages. But the region’s water managers said they’ve decided to plan for more of the dismal runoff they’ve seen in the watershed during the past two years of extreme heat and parched conditions.

Bill Hasencamp, MWD’s manager of Colorado River resources, said if such extreme dryness persists for another year or two, then Mead could end up at such low levels that cuts would become “unmanageable.”

[…]

When Buschatzke testified in a congressional hearing on the Colorado River last month, he noted that snowpack in the Colorado River Basin peaked at 89% of average this year, but runoff in the watershed was only 33% of average.

“This phenomenon is likely the result of the hotter and drier conditions caused by climate change,” Buschatzke said in his written testimony. “This trend is one that water managers must take into account as we plan for the future of the Colorado River.”

[…]

Since 2000, the Colorado River has been ravaged by a series of mostly dry years, which have been compounded by the heating of the planet with the burning of fossil fuels. In that time, the flow of the Colorado River has declined nearly 20% below the 20th century average.

Scientists have estimated that about half the decrease in runoff in the watershed since 2000 has been caused by unprecedented warming. And this heat-driven aridification is projected to significantly worsen as temperatures continue to climb.

Brad Udall, a water and climate scientist at Colorado State University, recently likened the planned water reductions under the existing deal to a parachute — one that is too small and being opened too close to the ground…

Given the alarming declines in the river’s reservoirs, the flaw with the parachute analogy is that the end of the story would put the parachutist safely on the ground, Udall said.

“We’re landing on the edge of a cliff, if you will. And there’s still further to fall. We need another parachute here,” Udall said.

Hopefully that next parachute will be ready well before 2027, he said, when the existing rules expire, and the Southwest needs to have long-term plans in place for adapting to a hotter, drier watershed and a river that yields less water.

Lake Mead behind Hoover Dam. Lake Mead last month [May 2021] fell to its lowest level since the Hoover Dam was built in 1936. The shoreline has dropped 45 meters since the reservoir was last full in 2000. Photo by Ken Neubecker via American Rivers

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