Drought in New Mexico was expected to only worsen in the next half century, as temperatures rise and water resources are stressed.
State researchers pointed to climate change as having a long-term devastating impact on the state’s water resources from the snow packs of the Sangre de Cristo Mountains to the north, south to the streams of the Lower Pecos River.
The Interstate Stream Commission, as part of its 50-year water plan, studied the impacts of climate change on New Mexico’s waters in hopes of devising guidance on how to manage water for the future.
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The state’s initial findings were presented Wednesday during a public meeting and policy recommendations and deeper research were forthcoming, said Rolph Schmidt-Petersen, director of the New Mexico Interstate Stream Commission.
The 50-year plan was being developed in four phases, with the final report and plan expected to be complete between February and April 2022.
In the meantime, scientists know one thing: the state will continue warming throughout the next half century and water availability will continue to decline as a result.
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Schmidt-Petersen said New Mexico was already under a severe drought for the past 20 years, and the impacts were also felt throughout the Western U.S., despite recent heavy rainfall in parts of the state.
“This year except up until recently it has been described as the deepest drought in the last 20 years. That can be a difficult place to be in,” he said. “There’s a lot that’s been done in New Mexico to plan, but we also need to look forward. We don’t know what then next 20 years will bring or what the next 20 years after that will bring.”
The State first developed a water plan in 2018, and multiple municipalities and local organizations around New Mexico already spent up to $1 billion on water plans and management efforts to contend with drought.
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But the State of New Mexico under orders from Gov. Michelle Lujan Grisham opted to look further into the future, creating a body of research that could inform water management statewide for the next five decades.
Nelia Dunbar, director of the Bureau of Geology and Mineral Resources at New Mexico Tech and the state geologist, said average temperatures by decade were on the rise since 1930 in New Mexico and she expected that trend to continue.
Rainfall and precipitation, Dunbar said, was likely to stay the same.
She said she expected New Mexico’s average temperature to climb by 5 to 7 degrees Fahrenheit by 2070.
“The bottom line is the temperature in New Mexico will continue to climb,” Dunbar said. “The question is how much. The precipitation is likely to not change a lot.”
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Warming’s effects on New Mexico’s waters
Warming would cause myriad impacts to New Mexico’s water and environment, Dunbar said, including lower stream flow and longer and hotter droughts.
The state would also see decreased snow packs and runoff, more forest fires leading to flooding and degradation of surface water quality.
Dunbar pointed to the state’s water budget which takes into account the amount of rainfall and runoff along with water lost into the atmosphere.
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She said the state gets about 95 million acre feet (AF) in precipitation annually, but looses about 75 million AF to transpiration, when the water is given off by vegetation and returns to the atmosphere.
Another 17 million AF is lost to soil evaporation, leaving just 1.7 million AF for recharging aquifers and about 1.5 million AF in runoff.
An acre foot is the amount of water needed to cover a single acre one foot deep.
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“One of the main things that happens to rainfall in New Mexico, is plants take up a lot of that precipitation into their roots. Then a lot of that precipitation transpires from the plants into the atmosphere,” Dunbar said.
“Even with constant precipitation, because of rising temperatures, New Mexico will become more arid. Warm air can hold more moisture than cold air.”
She also warned this could lead to smaller snow packs, when snow falls and builds up on the mountains before melting and feeding streams and rivers.
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“The expectation is that snow pack and spring stream flow will decline,” Dunbar said. “Snow pack will decline over the next 50 years. Stream flow will also decline, but there’s a little more variation in our models.”
The temperature increases and impacts on precipitation would not be uniform throughout the state, Dunbar said.
Researchers broke New Mexico up into four areas that would have similar rainfall at similar times of year.
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The northern mountains of New Mexico were expected to get more rain in the winter, while the bootheel to southwest would get less during that season, she said, while rains would decline in the eastern plains.
Summers would see less rain in the northwest and more in the bootheel, with potential increases to the east.
Dunbar said it would be hard to predict, but that researchers expected the high mountains to the north, northwest high desert, Rio Grande Valley in the southwest and the eastern plains region to each have similar impacts.
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These areas can vary widely even during an extreme rainfall event, she said, as the northwest San Juan Basin region could see up to 4 inches of rain during a heavy downpour while in the opposite corner of the state in the Carlsbad area, up to 24 inches could fall from a similar storm.
“New Mexico already is a state that has very extreme differences in precipitation in different parts of the states. It’s really hard [to predict] based on our past data that there will be more extreme precipitation moving forward,” Dunbar said. “In other states, it’s been demonstrated that extreme precipitation increases with global warming.”
Climate change effects ‘overwhelmingly negative’
Regardless of the water dynamics between different regions of New Mexico, Dunbar said one thing was clear: there would be hotter temperatures and less water.
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That means drastic changes to the landscape were inevitable, she said, brought on by stressed vegetation which could result in more incidents of wildfire.
Fires can lead to more flooding, erosion and soil damage, she said, while rising water temperatures and turbidity will be major impacts on water quality and effects on wildlife.
“In New Mexico, there has been some pretty catastrophic landscape changes brought on by wildfires. In a climate change scenario, the expectation is there will be big landscape changes moving forward,” Dunbar said.
“The impact of climate change on New Mexico’s water resources is unfortunately overwhelmingly negative.”
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Robert Boatman, manager of the Carlsbad Irrigation District (CID) – a local water co-op that serves farmers, ranchers and rural water users along the Pecos River in southern Eddy County – said the District depends on rainfall and runoff to feed its four reservoirs at Santa Rosa, Sumner Lake, Brantley Lake and Lake Avalon.
The forecast impacts to water supplies, he said, were troubling and mean the State and local agencies must work together to plan.
“Based on the forecast, it’s going to be a struggle for the Pecos River system,” Boatman said. “The CID depends on runoff and rain events. If those don’t happen, it will be a struggle for our users. That’s the only opportunity for our reservoirs to catch water.”
Boatman said he was hopeful the state’s planning efforts would be helpful in the decades to come.
The CID was already struggling for water amid the ongoing drought, with a priority call presently in place that could limit use by junior water rights holders on the river in favor of the more senior CID rights.
The state and CID were amid negotiations on the priority call, Boatman said.
“What they’re working in a positive thing. It demonstrates they’re paying attention to the environment,” Boatman said of the 50-year plan. “It gives us a sense of hope. We appreciate working with the state engineer on priorities on the Pecos. We appreciate their involvement in working on solutions.
“With the weather, you can’t ever predict, but the trends are going to be very difficult.”
Adrian Hedden can be reached at 575-618-7631, firstname.lastname@example.org or @AdrianHedden on Twitter.