The Colorado River’s desalination plant is on its last legs

The obscure Paradox Valley Unit keeps the Colorado River’s salinity levels in check for farmers, but causes quakes upstream.

  • Paradox Valley Unit Facility operations specialist Andy Nicholas at the Paradox Valley injection well, which shoots salty brine 14,000 feet beneath the Dolores River.

    Stephen Elliott

The Paradox Valley in western Colorado got its name because the Dolores River bisects it, rather than running through it in the normal topographical fashion. The landscape is short on people, long on sagebrush and probably best known for the dramatic red cliffs that loom over travelers making the long drive from Telluride, Colorado, to Moab, Utah. This remote valley was formed millions of years ago, when a huge dome of salt collapsed. Now, that salt remains, buried just within the earth, and as a white, crystalline blanket atop the red soil.

And that’s a problem. The waters of the Dolores pick up that salt and carry it to the Colorado River, where it eventually degrades the water quality for downstream cities and farmers. For about a quarter century, however, an unassuming facility has been tackling this salt. Every minute, in fact, the Paradox Valley Unit sucks nearly 200 gallons of brine, which is seven times saltier than ocean water, from wells here, then shoots it 14,000 feet beneath the earth’s surface, in order to keep it out of the river. It’s perhaps the most critical piece of a massive project designed to keep salt out of the Colorado River, but it’s in trouble. The facility itself is near the end of its lifespan, and there is no obvious replacement. Not only that: The re-injection process can cause earthquakes.

The federal Bureau of Reclamation operates the Paradox Valley Unit under the auspices of the Colorado River Basin Salinity Control Program, which was created by Congress in 1974. At the time, the river was highly saline once it reached Mexico, thanks to a combination of natural loading and upstream irrigation. That risked violating a U.S. water treaty with Mexico, and it also had what retired hydrologist Dan Luecke, a former consultant for the Justice Department and several environmental organizations, calls “adverse effects” on agriculture, on water treatment in urban areas and on the environment.  Salty water reduces crop yields when it’s used for irrigation on the 5 million acres of farmland along the Colorado, and it mucks up water treatment plants in the municipalities, including Los Angeles and Las Vegas, that rely on the river.

The Paradox unit began operating in 1991. Since then, it’s kept some 2.6 million tons of salt out of the river, making it by far the most productive of the dozens of the salinity control program’s projects in the watershed.

The locals, however, are paying for the downstreamers’ gains. Since injection began, approximately 6,000 earthquakes have shaken the valley, where previously seismic activity had been virtually unknown. Scientists generally agree that the tremors are caused by the deep injection at the facility, much as wastewater injection wells are causing quakes in oil and gas fields in Oklahoma and elsewhere.

Though the quakes are relatively minor, about 100 have been above the threshold for human detection. There have been no official reports of damage, but one local farmer said that the last significant earthquake, a 4.4-magnitude event in January 2013, broke a dam and caused a creek to flood; his wife thought a truck had crashed into their home. After that episode, operators reduced brine injection pressures and volumes. Since then, the tremors have calmed a bit.

Meanwhile, the facility is facing its own existential crisis. The injection well deposits the salty brine about 2.5 miles down into the Mississippian Leadville formation, in a space that will eventually fill up, rendering the facility useless. Officials aren’t sure how long they have, but Andy Nicholas, facility operations specialist, estimates about 10 years, 20 tops.

So the Bureau of Reclamation is scrambling for another way to get the salt out. Either a second well could be drilled, risking more tremors, or the salt could be disposed of in vast evaporation ponds. Both options have their drawbacks, including expense and the lack of available land nearby. An environmental impact study is underway to review alternatives, but it could take several more years.

Without the unit’s deep injection, the salt that covers the desert valley floor at Paradox, and the thousands of tons of it just beneath the surface, will continue to flow to the Colorado River and its millions of downstream users. Each ton of salt in the river causes $173 in damage to crops, water treatment facilities and the like, according to the Bureau of Reclamation. That puts the price tag for going without the Paradox unit at around $457 $19 million annually, and that doesn’t account for the damage done to fish, bugs and other aquatic life. As Luecke says, something has to be done: “It’s important that that salt be taken out.”

High Country News Classifieds