by Tom Ribe
The livestock industry in the Southwest is at the core of a critical water crisis.
The Southwestern states enjoy an enviable place in the world. Perched on some of the most beautiful land in America, these states attract residents and visitors with their sunny disposition, wide expansive spaces, and mild winters. But that sunny weather comes at the cost of aridity and with the climate warming, it is getting drier even as more people move into the Southwest. Here, evaporation exceeds precipitation and as people continue to move into these states, limited water supplies are being strained beyond their limits.
Overlaid on this reality is the livestock industry which uses most of the water in the Southwest. It limits river flows by damaging headwaters and uses water high in the mountains before streams can feed rivers. As the human population grows, the water supply is strained by climate change and the small livestock industry using more than its share.
For the last twenty years, the Southwest has been experiencing drought. Is this drought part of the cyclic droughts that have always afflicted the Southwest or is it somehow influenced by human caused climate change? Understanding the overall climate of the Southwest helps us put the cattle industry in context of a declining water supply in a warming region.
The Southwest is dominated by arid conditions. Two hundred million years ago, the Southwest was covered with forests and marshes, but with the rise of the Sierra Nevada around 80 million years ago, the Southwest found itself in the rain shadow of this immense mountain range and aridity spread over the Southwest and north into what is now Nevada. Four desert types developed in this rain shadow depending on elevation and modern humans have settled in these deserts, seeking water to sustain them in the sunny weather that many find appealing.
The Southwestern states: Utah, New Mexico, Colorado, Nevada and Arizona and southern California depend on two river systems and ground water for their water supplies: the Rio Grande east of the continental divide and the Colorado River on the west side of the divide.[1] The Rio Grande gets most of its water from snowmelt in the eastern San Juan Mountains in southwest Colorado, while the western part of that mountain range contributes significantly to the Colorado River, along with other ranges of the Rockies as far north as the Wind River Range in Wyoming.
The Rio Grande is a relatively small river because its headwaters lie in the rain shadow of the main mass of the San Juan Mountains and because the Sangre de Cristo Range that rises over the river to the east contributes little to the Rio Grande for a variety of reasons. Yet a large portion of its flow is used to grow cattle feed for dairies before it leaves the state of Colorado.
For its part the Colorado River has a robust source of water as the long chain of the central and southern Rockies contribute to its water supply. These are the west facing slopes of the Rockies and despite the presence of the Sierra Nevada and their rain shadow creating mass 700 hundred miles to the west, the Rockies still get significant snowfall from winter cold fronts tracking in from the Pacific Ocean.
Humans have not developed technology to create water, so we depend on the environment for our water supply. The only technology we have for producing fresh water is desalination, which has always been a technology with major economic and environmental trade-offs. The conventional process requires large amounts of electricity to run the pumps that force seawater through reverse osmosis filters and the process produces waste saline brine that can damage marine ecosystems if it is disposed of near shore.
Recently a new desalination technology has arrived from Norway called subsea desalination where the pressure of seawater at great depths (1600 feet) forces the seawater through reverse osmosis filters that remove salt molecules from water molecules that are then pumped to the surface. This process is less expensive than conventional desalination since the water pressure for filtration comes from gravity rather than electric pumps. Even so, it is still more expensive that pumping groundwater and has yet to be scaled up for current demands.[2]
In the prehistoric past, we know that indigenous people abandoned areas of the Southwest when drought reduced surface water supplies. Places like Frijoles Canyon in Bandelier National Monument were abandoned by Puebloans during a mega-drought in the late 1400s. Similar drought forced migrations happened around the Southwest in pre-European settlement times. Famously, the Hohokam who inhabited the valley where Pheonix, Arizona stands today and had extensive canals systems for water, abandoned the valley around 1500 CE.
We are not immune from the same drought pressures though now we have deep well drilling technology that prehistoric cultures couldn’t imagine. Today our water demands vastly exceed those of prehistoric Southwestern cultures. But our water supply is the same, albeit with better technology for extracting more of it.
The six states of the Southwest have sixty million people living in them. Their population is growing by over a half a percent per year, with Utah and Arizona growing the fastest and California growing the slowest except for New Mexico which has lost population. People are congregating in Los Angeles, Las Vegas, Salt Lake City, Phoenix and Tucson which concentrates water demand. Forty million people rely on the Colorado River for their water supply while 13 million depend on the Rio Grande for daily water supply. Meanwhile, the Colorado River supplies water for 5 million acres of farmland, some of the most productive farmland in the world.
Something has to give. We cannot continue to pander to a small industry, dairies and cattle, and have growing cities and now, data centers, that use huge amounts of water for cooling their computers. Cattle can be grown in wet states east of the 45 parallel. Yet we have no mechanism as a society to close down a vast industry that is damaging the public interest yet makes money for its shareholders.
[1] The continental divide is the long rise in the western center of North America where the waters divide between the Atlantic and Pacific Oceans. Waters on the east side of the central and northern Rockies flow toward the Mississippi River while those from the Southern Rockies generally flow to the Gulf of Mexico, an appendage of the Atlantic Ocean. Waters on the west side of the Continental Divide flow toward the Pacific Ocean and fill the Colorado River from southern Wyoming into Colorado and New Mexico.
[2] https://www.scientificamerican.com/article/deep-sea-desalination-pulls-drinking-water-from-the-depths/
