With the Colorado River’s giant reservoirs declining toward critically low levels, negotiators for California, Arizona and Nevada announced a new water-saving plan for the next two years.

Representatives of the three states said in a written statement Friday night that their plan aims to “stabilize the Colorado River through 2028.” It will require larger cuts in water use than they had pledged previously in talks with other states and the federal government.

“We have stepped up to establish a leadership position to protect the system for another two years,” said JB Hamby, the chairman of California’s Colorado River Board. “Without that, the system will continue to decline.”

The three states’ negotiators said their plan identifies more than 3.2 million acre-feet of water cutbacks through 2028, building on their previous proposal.

Representatives of the three states negotiated the short-term deal after they deadlocked in talks with four other states on a long-term plan for sharing the river’s diminishing water.

Lake Mead, the country’s largest reservoir near Las Vegas, is now 31% full.

And upstream on the Arizona-Utah border, Lake Powell is just 24% full. In the coming year, the reservoir could decline to a point where water can no longer pass through intakes to generate hydroelectric power.

The Colorado River provides water for about 35 million people and 5 million acres of farmland, from the Rocky Mountains to northern Mexico. The water was originally divided among the states in 1922 under an agreement called the Colorado River Compact.

The river flow has shrunk dramatically since 2000, and research has shown that global warming is intensifying the dry conditions.

This year, the snowpack in the upper portion of the river’s watershed in the Rocky Mountains measures just 22% of average, the smallest on record. That will translate into very little runoff reaching the river’s depleted reservoirs this year.

In a letter to Interior Department officials, the states’ top negotiators said they came up with the three-state plan because “quick and decisive action is urgently required.”

“We hope these actions can provide additional time to develop a longer-term approach involving actions to achieve reductions in use by all seven states,” they said.

The plan calls for reducing California’s use of Colorado River water by about 13% in 2027 and 2028. Arizona and Nevada agreed to larger cutbacks.

Managers of various water agencies still need to negotiate the specifics of how the water cuts will be divided between cities and farming areas.

Stepped-up conservation by growers will be key, as about three-fourths of the river’s water is used for agriculture, producing crops such as hay for cattle and vegetables like lettuce and broccoli.

Over the last three years, the states have turned to voluntary water cutbacks and federal payments to farmers who agree to leave fields dry part of the year.

State leaders have urged the Trump administration to provide money to support conservation efforts. California Gov. Gavin Newsom, along with governors of the other six states, stressed this in a joint letter to Interior Secretary Doug Burgum on Thursday, saying “solutions will require significant federal funding to match our state investments.”

The negotiators for California, Arizona and Nevada reiterated that, saying the water-saving plan is “contingent on the availability of federal and other funding.”

They said they plan to work out the specifics of the water cuts by August.

Over the last five years, cities across Southern California have received nearly one-fourth of their water from the Colorado River. In California’s Imperial Valley, farms depend entirely on the Colorado River.

Shivaji Deshmukh, general manager of the Metropolitan Water District of Southern California, said it’s unfortunate that all seven states have not been able to reach an agreement.

He said the three states’ plan “aims to address the historically dry conditions in the near term.” At the same time, he said there is still hope that “an agreement can be reached in the next year among the seven states for broad conservation programs.”

“We must recognize that the river is changing,” Deshmukh said, “and the only way we can ensure the communities, businesses and ecosystems across the Southwest have the water they need in the decades to come is by all seven states working together.”

The Metropolitan Water District, which delivers water to 19 million people, currently has ample water coming from Northern California and stored in reservoirs, so there are no immediate plans for extra water-saving measures in the region this summer.

The Las Vegas area has already saved so much water over the last two decades that it’s surpassed its latest water-saving pledge, said John Entsminger, general manager of the Southern Nevada Water Authority. The area has dramatically reduced water use by targeting the removal of water-guzzling lawns and adopting other water-saving rules.

“This isn’t a situation that’s snuck up on Las Vegas,” Entsminger said. “We spent 25 years driving down our water usage and being the most efficient urban area in the United States.”

Entsminger said he went into the negotiations two and a half years ago hopeful that the seven states could agree on a long-term plan for the next 30 years. Since that hasn’t yet been possible, he said, the short-term deal “buys us time.”

In their letter to the federal government, the negotiators for California, Arizona and Nevada said those representing the upstream states — Colorado, Utah, Wyoming and New Mexico — have so far refused to commit to mandatory reductions.

They said they hope the latest proposal can help the seven states eventually agree on a long-term approach.

“Everybody has to be more efficient and use less water,” Entsminger said.

By committing to conserve more, the three states are offering “a bit of an olive branch” to the other states, he said, to show how the region can reach a consensus on living within the river’s limits.

The Orion Nebula provides a master class in the study of stellar formation. Yet, many of its youngest stellar objects are still swaddled in their birth crèches, hidden by clouds of gas and dust. The Very Large Baseline Array (VLBA) radio telescopes have managed to punch through the dusty obscuring veil to study a pair of young binary systems called Brun 656 and HD 294300 born in the Nebula.

The result of the observations is a very accurate calculation of the masses of the stars in those systems. Lead researcher on the observations, Dr. Sergio Abraham Dzib Quijano, from the Max Planck Institute for Radio Astronomy pointed out how important this measurement is. “Stellar mass is the most fundamental property of a star,” he said, “yet it is notoriously difficult to measure for young, embedded systems.”

VLBA solved the difficulty by observing at radio wavelengths of 5 GHz using the full array of telesscopes. That 5 GHz is a region where dust is transparent, and radio wavelengths can get through. The high resolution capability of the array was able to resolve the tight binary pairs more easily than telescopes at other wavelengths can achieve.

*A montage of VLBA locations and their antenna installations. Credit: Image courtesy of NRAO/AUI and Earth image courtesy of the SeaWiFS Project NASA/GSFC and ORBIMAGE*

Probing the Orion Starbirth Region

The Orion nebula lies about 400 parsecs (~1300 light-years) away from us. Over millions of years, it has birthed a diverse population of stars, ranging from massive hot ones to the binaries being studied to brown dwarfs (objects too cool to be stars but too hot to be planets). In addition, it’s populated by hundreds of young stellar objects (YSOs) that are in all stages of early evolution.

An October 2010 image of the Orion Molecular Cloud region, the site of a number of young stars, brown dwarfs, and young stellar objects still in the process of formation. Courtesy Rogelio Bernal Andreo and Wikimedia Commons.

Stars are born in batches, and many end up in binary pairs, triplets, and smaller clusters. Determining their masses is an important step in figuring out their stage of evolution as well as the existence of any protoplanetary systems. Many of those remain hidden from the view of optical telescopes, but can be “seen” in infrared wavelengths and radio frequencies. Radio measurements can also detected evidence of magnetic fields and activity in some regions where stars are forming or are newborn. In particular, the team used VLBA to study the quadruple star system V* NU Orionis. They found that its C component as an intermediate-mass (~7 solar masses) star with nonthermal radio emission. It also offers rare evidence of magnetic activity in a star that’s close to being a high-mass star.

The VLBA observations are an important step in understanding the early epochs of stars’ lives. “These accurate mass measurements now turn Orion into a precision laboratory for testing how young stars form and evolve,” said Dr. Jazmin Ordonez-Toro, postdoctoral Orquídeas fellow at the Astronomical Observatory at the University of Nariño, who co-led the study of the binaries, “These measurements vastly expand our understanding of how stellar neighborhoods like our own are built.”

VLBA Monitors Dynamics and Positions

In its sampling of binary stars in the Orion nebula, the VLBA watched as the partners orbited each other. The characteristics of those orbits gave a very good measure of the masses of each of the stellar partners. The VLBA’s abilities allow it to detect even the smallest shifts in position of a celestial object. This means measuring tiny shifts in a star’s apparent position on the sky over months and years. The VLBA can repeat its observations of the same area of the sky and coordinate the observations between all of its member telescopes. They’re scattered across the world, from the U.S. to Hawai’i and out to the Virgin Islands. This gives astronomers a star’s position with millisecond accuracy. By comparing how that position changes from epoch to epoch, the subtle orbital motion caused by the gravity of a companion star becomes quite obvious. Astronomers then use that motion to infer the mass of each star in the system.

*M43 is part of the larger Orion Nebula. The central star is a young irregular variable designated NU Orionis or HD37061. It was part of a study of young stars in the Orion Nebula made by the VLBA. Courtesy N.A.Sharp/NOIRLab/NSF/AURA*

The VLBA measurements are the first such characterizations of multiple YSOs in the Orion birth complex. The data provided show that VLBA astrometry (the precise measurements of stellar distances, motions, and positions) demonstrates a powerful tool for measuring stellar masses and other characteristics in young multiple-star systems. That information can be fed into models of stellar formation and evolution, and enable further studies into the magnetic activity involved in these infant systems.

Why Care About Mass?

Astronomers characterize stars by their masses. A given star’s mass foretells its entire evolutionary history. It tells us what’s happening in its nuclear furnace as it forges new elements over time. Eventually, its mass will determine how it dies, as a planetary nebula (as our Sun will do in some 10 billion years) followed by billions of years as a white dwarf. Or, if it’s massive enough, it could explode as a supernova, leaving behind a neutron star or even a black hole. So, measuring the mass of a star, particularly those youngsters in the Orion Nebula is an important contribution to our understanding of stellar evolution. Not only that, but given the heavy elements all stars leave behind, stellar mass also plays a role in the formation of planets around stars, and influences the characteristics of those worlds.

Astronomers use mass measurements as part of developing a standard model of young-star formation. The VLBA observations were compared with those models with some mixed results. Some observations matched quite well, while at least one observed pair didn’t match at all. That could mean that the model needs some tweaking before it accurately reflects the reality of young-star formation. Interestingly, the VLBA observations found a few previously hidden close companions, as well as compelling evidence that strong magnetic activity can persist in relatively massive young stars.

For More Information

Unraveling the Mass Mystery of Orion’s Young Stars

Dynamical masses of young stellar objects with the VLBA: DYNAMO-VLBA