Refining the answer to ‘how much?’
How much water does New Mexico have? The answer depends on a variety of factors that remain little understood, high variable, and in need of better definition. At least that was the answer of a panel of experts at the 57th Annual NM WRRI Conference held Aug. 28 in Las Cruces. Although there are general answers to the question, research is needed to refine the numbers, they say.
Sam Fernald, director of NM WRRI and an NMSU faculty member, said understanding how much water is available to the state depends on “bringing a number of different perspectives” together to deal with water management issues. “We need more research,” Fernald said, adding that a better understanding of the quality and extent of groundwater, groundwater-surface water interactions, and the kinds of supply variability that the state will be facing in coming years are all needed to better piece the puzzle together.
Current figures suggest New Mexico’s average yearly “water budget” is about 1.2 million acre-feet of usable water, Fernald said.Yet there are two million acre-feet of surface water withdrawals and four million acre-feet of total withdrawals in the whole state. Part of the reason this is possible is that water for agriculture is reused as it flows downstream, he said. The balance of the withdrawals are made by tapping groundwater. Fernald referred to the state’s groundwater as “our trust fund. We are not saving it for a rainy day.”
Dagmar Llewellyn, hydrologist with the Bureau of Reclamation, said an assessment of climate change must also be factored into water estimates. She said most water users agree that usable and manageable water “is going to be or already is in decline.” At the same time, demand is increasing, causing a gap between supply and demand. “We try to avoid talking about climate change, but it’s incumbent upon us to tackle the problems of future supply,” she said.
Llewellyn said a study of climate change impacts on the Rio Grande is beginning this fall and the Bureau of Reclamation will be looking for partners to participate. Chaining of events connected with climate change creates highly variable water scenarios for New Mexico, Llewellyn said. “We have to embrace the uncertainty and concentrate on adaptive management.”
Although climate models do not necessarily predict less precipitation for New Mexico, where and when that water will be available may change with new conditions, she said. Heat and drought in the past two years have already pushed the state outside its normal envelope in temperature measurements.
Another factor to be considered is the ability of the state’s water infrastructure to work in an effective way to preserve water and deliver it where it is needed. “A substantial portion of the New Mexico infrastructure is more than 60 years old,” said Del Archuleta, CEO of Molzen Corbin and Associates, an Albuquerque-based planning, engineering, and architectural firm.
A group of 50 engineers studying the systems statewide gave it a grade of “C minus,” he said. The system scored a “C” (average) for reliability on a daily basis, but earned a “D” (poor) in the areas of operation and maintenance, Archuleta said. “Preventive maintenance is the last thing we fund in most places,” he said, noting that much of the state’s infrastructure is in “poor condition and not going to get better.” He called for better accounting of existing systems, with leak surveys and other measures and better planning for improvements.
“If we valued water, we would do things very differently,” Archuleta said. New Mexico is a state with low capital outlays and low water rates, he said. “We have to face up as a state, every one of us, to the true costs of water and allow our elected officials to build and run sustainable programs.”
Mike Darr, a hydrologist with the U.S. Geological Survey in Albuquerque reviewed his work to better understand groundwater in the major basins that cross the border between the U.S. and Mexico. Working with the water resources and research institutes in Texas, New Mexico and Arizona, the Survey has been hampered by funding cutbacks, but is continuing to get results, he said. Much of the effort to date has focused on the Mesilla Basin, in southern New Mexico, and the corresponding Conejos Medanos Basin in Mexico. Las Cruces, El Paso, and Juarez all draw drinking water from this aquifer.
Officials in Mexico are sharing pumping data with their U.S. counterparts to help get a better picture of basin supplies, Darr said. “We want to get at the groundwater quantity and how to share it fairly,” he said. Also under way is a project to use surface and groundwater monitoring data to model the interaction and relationships between the two water sources. Darr praised the work of the late Bobby Creel, associate director of NM WRRI, “opening the door for data exchanges with Mexico.”