By Scott Manning

How will increasing temperatures and  a warming climate affect future water supplies in Corrales and  other parts of New Mexico? Officials at the Middle Rio Grande Conservancy District (MRGCD), the New Mexico Interstate Stream Commission (ISC) and the Albuquerque-Bernalillo County Water Utility Authority (ABCWUA) are taking steps to conserve water and to conduct studies about the impact of climate change on the future water supply.

The director of the Interstate Stream Commission, Rolf Schmidt-Petersen,  explained this summer that New Mexico is going through a second year of water shortage caused by severe drought. In 2020, poor snowpack and reduced runoff water created severe drought conditions. That was compounded by a poor monsoon season this year. These water shortages have created problems for New Mexico with its water-sharing agreements with neighboring states.

One such agreement, the Rio Grande Compact, was signed by New Mexico, Texas, and Colorado in 1938 and details the water sharing promises between the three states. The agreement operates through water delivery debits and credits, in which states are held responsible for delivering the correct amount of water “payments” to other states.

Colorado is expected to deliver water to New Mexico, and New Mexico is expected to discharge water to Elephant Butte and deliver water to southern New Mexico and Texas. Currently, New Mexico is in compliance with its delivery requirements up to an “accrued debit” of 200,000 acre-feet of water.

The 2020 drought was severe enough to warrant the release of stored Rio Grande Compact Debit Water from the El Vado Reservoir to supplement Rio Grande flows. New Mexico is required to retain water in storage to the extent of its accrued debit in deliveries to Elephant Butte Reservoir, and may not store any Rio Grande water when Elephant Butte storage is low. Schmidt-Petersen explained that the water shortages in summer 2020 developed rapidly and that, without releasing the debit water,  the Rio Grande would have dried up through Albuquerque.

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Water officials hoped that the depleted water stores and severe drought situation last summer would be resolved  this year with modifications in MRGCD operations, a strong fall rainy period, and better snowpack in 2021.

Although the MRGCD made the intended modifications to its operations, the rest of 2020 and the beginning of 2021 continued to be dry, leading to further water supply concerns this summer. To make matters worse, the San Juan-Chama Rivers’ water supply has decreased in recent years.

New Mexico began 2020 with a water debit of 40,000 acre-feet, meaning the state was meeting its water sharing obligations, but that 40,000 acre-feet of Rio Grande water would need to be stored upstream before any water could be stored for later release to the middle valley.

But the severe drought last summer and subsequent debit water release yielded an increased water debit for 2021 of 96,000 acre-feet.

No snowmelt runoff was stored in New Mexico during the 2020-2021 winter because Elephant Butte remained low, New Mexico had a 96,000 acre-foot accrued debit, and the 2021 snowmelt runoff was poor.

So New Mexico began summer 2021 in a drought with little water storage. Schmidt-Peterson says that New Mexico has not experienced this kind of water scarcity since the early 1980s which makes the recent drought unprecedented in modern times.

Despite the recent droughts, there has been little discussion of revising the water sharing provisions in the Rio Grande Compact.

In general, water shortages lead to litigation over the terms of preexisting interstate compacts, not the adoption of new water agreements. Schmidt-Petersen suggests that such litigation is the more common negotiation strategy because renegotiation is difficult: the current Rio Grande Compact was adopted into state law by New Mexico, Colorado and Texas before also becoming federal law.

This long legislative process makes it unlikely that water agreements can be completely reworked and replaced in times of water shortages because different parties will disagree about the terms of the renegotiation.

The Rio Grande Compact has come under litigation in three cases during its history. First in the 1950s, Texas pursued legal action against New Mexico over the operations of El Vado Reservoir. Then in 1966, New Mexico and Texas took legal action against Colorado because that state had not adhered to its water-sharing agreements.

The third case began in 2014 when Texas filed a lawsuit against New Mexico, claiming that New Mexico had misused the water released from Elephant Butte that was supposed to be delivered to Texas.

The ISC plans to continue to navigate the Rio Grande Compact for the foreseeable future.

Instead of revising the Rio Grande Compact, agencies like the ISC, MRGCD and ABCWUA try to implement strategies to protect farmers from droughts, reduce water usage among New Mexico residents and within the river system, improve water deliveries to Elephant Butte, and protect endangered species and the environment that depend on available river water.

Last fall, the MRGCD and ISC notified farmers of the ongoing drought crisis, and advised that farmers in the Middle Rio Grande District refrain from farming. These early notifications provided farmers with time to plan their 2021 growing season accordingly.

According to MRGCD Chief Engineer Mike Hamman, a Corrales resident, the agency has implemented an annual fallowing program in which farmers can choose to fallow their land for a payment instead of planting during drought years; through this program 1,000 acres of farmland have been left fallow.

More generally, it was announced earlier this fall that the MRGCD has been awarded $2.9 million by the U.S. Department of Agriculture to fund improvement to water infrastructure throughout the district to improve water efficiency. The money will be spent on  improvements to the district’s primary canals and laterals as well as for farms, including conservation easements.

Other efforts to confront climate change are also underway. The MRGCD has helped fund the Upper Rio Grande Basin Study that aims to address the impacts of climate change on water resources.

Carlos Bustos, the program manager of water conservation at the ABCWUA, said the authority is doing its part to mitigate the risks of water shortages in the Albuquerque area.

Given the ongoing drought, Albuquerque residents are no longer using surface water to meet the water needs. Instead, the City of Albuquerque is drawing on water in the aquifer.

Bustos explained that water usage per capita in the region is below the water target set by ABCWUA, meaning that Albuquerque residents are using the groundwater resources responsibly.

As a result, ABCWUA has not observed reductions to the aquifer greater than their models predicted.

Even so, water conservation efforts can be further improved. According to Bustos, the ABCWUA has adopted strategies to further reduce water consumption in Bernalillo County. The ABCWUA focuses its efforts on community outreach and education about water usage in the community.

First, the Authority does frequent outreach to the top 5-10 percent of residential water users in the city and encourages these residents to cut back their usage.

Second, the authority provides free consultations and 40-50 audits each week to help residents become more water efficient. Third, the authority provides an online educational training course that informs residents about ways to cut back on their water usage. The course includes lessons on how residents can repair and re-landscape their yards to be more efficient. The class has had more than 600 participants by this summer, and the ABCWUA records that the residents who have attended the class have cut down their water usage.

When these outreach efforts fail to reduce water usage by some residents, the ABCWUA may issue warnings and fines. Bustos explained that the authority tries to avoid these punitive actions and restrictive measures by promoting outreach and education as much as possible.

The authority has also previously entered water-sharing agreements with the MRGCD before in which stored water is released in the Albuquerque region to extend the irrigation season for farmers. Bustos says that more of these agreements may be implemented in the future to supplement the region’s water vulnerabilities.

In the short term, Bustos is hopeful that the rest of the year won’t see further restrictions. But water officials fear that New Mexico will experience ongoing water concerns in the long term due to climate change.

To better understand the challenges posed by climate change to water resources in New Mexico, the ISC is conducting a 50-year plan that assesses the impacts of climate change, determines the resiliency of New Mexico communities to these changes, and proposes adoption strategies, where needed.

There are four phases of the 50-Year Water Plan.

Phase 1 began in January 2021 and ended by March 1. This phase involved assessing the process with the New Mexico Water Dialogue, coordinating experts with the New Mexico Bureau of Geology and Mineral Resources (NMBGMR), and building approaches to the plan.

Phase 2 of the plan, the “Leap Ahead Analysis,” began on March 1 and ended June 30. The purpose of the analysis was for experts led by the NMBGMR to compile scientific information about the impact of climate change on New Mexico communities and water supplies over the next 50 years.

The planning effort is now in Phase 3, the outreach and assessment phase, where the ISC intends to host meetings with citizens of New Mexico to explain the findings of the “Leap Ahead Analysis” and to interview citizens to determine the degree of resilience New Mexico communities have to the challenges posed by climate change.

The ISC’s other partners in the effort, the U.S. Army Corps of Engineers, the New Mexico Water Resources Research Institute, and the N.M. Indian Affairs Department, will play a role. This phase will continue through January 2022.

During Phase 4 of the plan, scheduled for spring 2022, the ISC and collaborating authorities will produce, review and finalize a 50-Year Water Plan that will contain guidelines for preparing for climate change, adopting efficient water usage strategies, and improving water resiliency throughout the state.

The water shortages in New Mexico are driven by both a multi-decade climate cycle and a warming climate. In the coming half-century, the NMBGMR reported the average temperature in New Mexico is expected to increase by five to seven degrees Fahrenheit, while average precipitation is expected to stay relatively constant.

The warmer climate will accelerate processes such as evaporation and transpiration that remove water from the ecosystem and environment. Therefore, a hotter climate, even with constant levels of precipitation, will further strain New Mexico’s water supplies.

But the hotter climate will impact the environment in further ways as well. A warmer climate will strain vegetation and allow fires to proliferate, thereby harming plant cover in New Mexico biomes. This biome damage makes the environment less resilient to erosion and flooding, meaning that storms will cause greater environmental damage.

That damage could disrupt normal drainage systems and damage water infrastructure, further straining water resources. Water quality will decrease as well with the increase of water temperature and potential growth of bacteria in water supplies.

The analysis demonstrates the need for the state to continue to assess its vulnerabilities to climate change. The ongoing drought in the state causes short term water shortages that strain farmers and New Mexico residents alike.

Water concerns are unlikely to go away as New Mexico becomes hotter and drier in the coming decades.

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