Here’s the release from the Bureau of Reclamation (Marlon Duke/Patti Aaron):

The Department of the Interior, Bureau of Reclamation and representatives from all seven Colorado River Basin states gathered today and signed completed drought contingency plans for the Upper and Lower Colorado River basins. These completed plans are designed to reduce risks from ongoing drought and protect the single most important water resource in the western United States.

“This is an historic accomplishment for the Colorado River Basin. Adopting consensus-based drought contingency plans represents the best path toward safeguarding the single most important water resource in the western United States,” said Reclamation Commissioner Brenda Burman. “These agreements represent tremendous collaboration, coordination and compromise from each basin state, American Indian tribes, and even the nation of Mexico.”

In addition to the voluntary reductions and other measures to which the basin states agreed, Mexico has also agreed to participate in additional measures to protect the Colorado River Basin. Under a 2017 agreement, Minute 323 to the 1944 U.S. – Mexico Water Treaty, Mexico agreed to implement a Binational Water Scarcity Contingency Plan but only after the United States adopted the DCP.

The Colorado River, with its system of reservoirs and water conveyance infrastructure, supplies water for more than 40 million people and nearly 5.5 million acres of farmland across the western United States and Mexico. The reservoirs along the river have performed well—ensuring reliable and consistent water deliveries through even the driest years. But, after 20 years of drought, those reservoirs are showing increasing strain; Lake Powell and Lake Mead, the two largest reservoirs on the system and in the United States, are only 39% and 41% full respectively. And, while the basin experienced above-average snowpack in 2019, the total system storage across the basin began the water year at just 47% full.

“The urgency for action in the basin is real, and I applaud all of the parties across the seven states and Mexico for coming together and reaching agreement to protect the Colorado River,” said Burman. “I’m glad to finally say that ‘done’ is done.”

From The Arizona Republic (Ian James):

The Colorado River just got a boost that’s likely to prevent its depleted reservoirs from bottoming out, at least for the next several years.

Representatives of seven Western states and the federal government signed a landmark deal on Monday laying out potential cuts in water deliveries through 2026 to reduce the risks of the river’s reservoirs hitting critically low levels.

Yet even as they celebrated the deal’s completion on a terrace overlooking Hoover Dam and drought-stricken Lake Mead, state and federal water officials acknowledged that tougher negotiations lie ahead. Their task starting next year will be to work out new rules to re-balance the chronically overused river for years to come.

Figuring out how to do that will be complicated because the Colorado River, which supplies water for vast farmlands and more than 40 million people, is managed under a nearly century-old system of allocations that draws out more than what flows in from rain and snow in an average year.

The river’s reservoirs have fallen since 2000 during one of the driest periods in centuries, and global warming is cranking up the pressures by contributing to the declines in the river’s flow.

“Look at all we have accomplished by working together,” said federal Reclamation Commissioner Brenda Burman, who signed the agreements alongside the states’ representatives. “All the states should be commended for finding a path forward.”

She called the deal historic and said it adds an important new chapter to the rules that govern the river.

“But our work is not done,” Burman said. “We know we have even greater challenges ahead.”

Federal and state officials began talking about the need for a drought deal in 2013, and the negotiations got underway in 2015.

The set of agreements includes two separate but interrelated drought contingency plans: one for states in the river’s Upper Basin — Colorado, Wyoming, Utah and New Mexico — and the other for the Lower Basin states — Arizona, Nevada and California.

The drought plans are designed to prop up the levels of Lake Mead and Lake Powell, the nation’s largest reservoirs, between 2020 and 2026. Lake Powell is now 40% full, and Lake Mead sits 41% full.

During the talks on the agreement last year, Lake Mead had appeared headed for a first-ever declaration of a shortage by the federal government. But this winter left the Rocky Mountains blanketed with heavy snow, unleashing a bounty of runoff that’s expected to avert a shortage for another year.

“One good year is helpful,” Burman said. “But it doesn’t fix a 19-year drought and it doesn’t do anything to predict for us what’s going to happen next.”

The audience of water managers and government officials broke into applause after the signing and posed for photos with the Hoover Dam, its low water levels starkly outlined, in the background.

Missing from the celebration was the largest single user of the Colorado River, California’ Imperial Irrigation District, which is suing to challenge the deal.

A new reality driven by global warming

Water managers and supporters of the deal have praised the Lower Basin’s Drought Contingency Plan, or DCP, as “bridge solution” to get the region through the next several years until 2026 while reducing the risks of a crash. But they also stress that it’s merely a stopgap measure — a temporary fix on top of the existing 2007 guidelines for managing shortages — and that it will provide a short window of time to start to plan bigger steps.

“We’re in a moment where we’re going to take a pause and recognize the progress we’ve made. But I think it needs to be a short pause so that we get working on the renegotiation of the guidelines,” said Kevin Moran, who leads the Environmental Defense Fund’s Colorado River program. “I think it’s in everyone’s interest that we move those conversations as quickly as possible forward.”

[…]

When water officials finished negotiating the last set of rules for dealing with a potential shortage in 2007, they had expected those rules to work through 2026. But only halfway through that period, they realized the measures weren’t nearly strong enough. And that forced them to negotiate the new set of drought agreements to finish off the period…

Adapting that system to a hotter planet, Moran said, will require posing tougher questions and looking at ways of boosting conservation and managing demand for water across the Colorado River Basin.

“The modeling looking forward would say we probably ought to be planning for somewhere between 15 and 35% additional reduction in flows driven by climate change,” Moran said. He said climate models present an outlook that is “very dire” and demands action…

A shortage is unlikely next year

Cynthia Campbell, a water adviser for Phoenix, said the challenges that lie ahead for negotiators are sobering.

“They know that they have a daunting task ahead of them, beginning in 2020, to try to come up with new operating rules that are going to keep us sustainable further into the 21st century,” Campbell said. “When they come back, Arizona is certainly going to be on the business end of cuts.”

There’s no way around that, she said, because the state holds the junior-most position in the water priority system. Under the framework that emerges from the next round of negotiations, she said, the state will probably face bigger reductions during a shortage than under the newly signed drought plan.

The latest projections by the U.S. Bureau of Reclamation show that in 2020 it’s unlikely a shortage will be declared at Lake Mead. The reservoir’s level now stands at 1,088 feet above sea level, about 13 feet higher than the threshold that would trigger a shortage declaration…

Critics: Arizona plan is not sustainable

Arizona water officials have called the state’s internal plan a landmark consensus agreement that effectively “shares the pain” and will address the water shortfall for the next several years.

But Arizona’s plan has also drawn criticism.

Some experts and environmentalists are concerned about the plan’s promotion of more groundwater pumping in parts of the state. They say using state money to drill more wells in Pinal County will only lead to declining aquifers. They also argue the state missed an opportunity to do more to encourage conservation.

“It is positive that the Colorado River basin states are looking at cutting back on river water use, but it is unfortunate that our state has chosen to augment the river water with more groundwater pumping,” said Sandy Bahr, director of the Sierra Club’s Grand Canyon Chapter. “Sadly, the Arizona plan is not sustainable and is designed to keep Arizona doing more of the same — unsustainable and thirsty agriculture and more and more sprawl development.”

She said looking past 2026, all the states should consider the river’s long-term water deficit, the effects of climate change, and how to do more for conservation while considering the health of the river.

“It is way past time for a Colorado River sustainability plan that centers on a healthy river that flows all the way to the sea and that provides for people, plants, and animals along the way,” Bahr said. “There is not time for patting ourselves on the back. We need to do more, now.”

In the meantime, even as the drought has eased across the West with the wet winter, concerns remain that the 19-year run of mostly dry years could continue. Earlier this month, a group of experts in a state advisory group recommended to Gov. Doug Ducey that a declaration of drought in Arizona should remain in effect.

Tom Buschatzke, director of the Arizona Department of Water Resources, called the Drought Contingency Plan “a huge incremental step forward.”

“It sets us up to have good conversations about what we need to do to deal with the projections of our drier future, climate change forcing reductions in flow, etcetera,” Buschatzke said. Discussions on the next round of plans should start soon in Arizona, he said, because “keeping the momentum going is really important.”

Update: May 21, 2019

From Inkstain (John Fleck):

Now that we have a DCP, what does this mean in practice?

According to the most recent Bureau of Reclamation 24-month study, Lake Mead is projected to end 2019 at elevation ~1,085 feet above sea level. Prior to the DCP, Lower Basin water users (Mexico, Arizona, Nevada, California) got a full allocation of water as long as Lake Mead’s elevation was above 1,075. Under the DCP, a new shortage tier has been added between elevations 1,090 and 1,075. The result is that, for the first time in the history of Colorado River management, there will now be mandatory water use reductions on the Colorado River.

What does this mean in practice? I ran down a quick summary this morning of the relevant data, comparing recent use with the cuts mandated under the DCP. It shows that, at this first tier of shortage, permitted use is less than the voluntary cuts water users have been making since 2015:

In other words, all of the states are already using less water than contemplated in this first tier of DCP reductions.