Photo of the Paradox Valley
The Paradox Valley and Dolores River Credit: By Mark Iverson from Seattle - San Juan Huts Day 5, CC BY-SA 2.0

For about two years, a Bureau of Reclamation salinity control facility in Paradox Valley was dormant; this month, it’s resuming operations at a reduced capacity.

The Paradox Valley Unit pumps naturally salty water from relatively shallow depths in the ground and injects it into deep wells, preventing the brine from following its natural course into the Dolores River, a tributary to the Colorado River. The point is to deliver less salty water to downstream Colorado River users.

The injections cause seismic activity, usually minor but occasionally significant—in March of 2019, Moab residents felt the ground shake when operations caused a 4.5 magnitude earthquake at the site of the facility near Bedrock, Colorado, over 30 miles away from Moab. After that event, the Bureau of Reclamation suspended operations to allow time for conditions to stabilize; this month, the agency restarted operations at the Paradox Valley Unit, beginning a six-month test run that will provide data to inform decisions about the future of salinity control activities in Paradox Valley. Some Colorado River activists say the facility is an example of poor planning by the bureau.

Salinity problems

The Paradox Valley Unit was planned and built under the 1974 Salinity Control Act, which authorized projects to help control the salinity of Colorado River water being delivered to members of the Colorado River Compact. Millions of people rely on Colorado River water for drinking, agriculture and electricity; the river also supports wildlife and ecosystems across the Southwest, and is valued by boaters and lovers of the outdoors. The water is managed through a complex set of agreements known as the Colorado River Compact or the Law of the River; parties to the agreement include Wyoming, Colorado, Utah, Nevada, New Mexico, Arizona and California, as well as Mexico. Part of the agreement dictates maximum salinity thresholds of water delivered to downstream users.

Once the Salinity Control Act was in place, water managers looked for locations that lent themselves to salt control. A geologic layer called the Paradox Formation, through and over which the Dolores River runs, is a naturally occurring source of salt being flushed into the Colorado River, making Paradox Valley a candidate for point-source salinity control. The process of researching locations, viability, and following procedures required by the National Environmental Protection Act took years; the Paradox Valley Unit began operations in the 1990s. It removes about 95,000 tons of salt a year in the form of briny groundwater and injects it 16,000 feet below ground surface.

“Prior to the operation of PVU, downstream Colorado River water users had decreased water quality and crop yields and reduced life of water infrastructure from corrosion,” said Justyn Liff, public affairs specialist for the Western Colorado Office of the Bureau of Reclamation, in an email to the Moab Sun News.

The Bureau of Reclamation estimates that the Paradox Valley Unit has financial benefits of “up to $23 million annually, including improved water quality, increased life of municipal and industrial infrastructure, and increased crop yields for all downstream water users in the Colorado River Basin,” according to a press release about operations resuming. The Paradox Valley Unit is the largest project in the Colorado River Basin Salinity Control Program.

Seismic activity

Researchers knew from the very beginning that the Paradox Valley Unit would trigger seismic activity.

A 2021 Bureau of Reclamation report on seismic activity in the Paradox Valley notes, “During the planning for PVU, it was recognized that earthquakes could be induced by the high-pressure, deep-well injection of brine.” The agency established an agreement with the U.S. Geological Survey to install a network of seismic monitors in the valley to keep an eye on seismic activity; the network, installed in 1983, has been updated and expanded several times.

The equipment detected no seismic activity in the first few years of monitoring, before injection at the PVU began; since the unit began operating, the network has registered over 10,900 shallow earthquakes in the vicinity of Paradox Valley. Over time, the quakes have occurred at increasing distances from the injection well.

On March 4 of 2019, a 4.5 magnitude earthquake was felt in Moab. [See “Earthquake shakes Moab area,” March 7, 2019 edition. -ed.]

“This earthquake was the largest PVU-induced earthquake to date,” according to the 2021 seismic report, which goes on, “More than 2,000 aftershocks occurred in the first five months following the main shock, resulting in the highest near-well seismicity rates in 20 years. Analyses indicate that aftershocks will continue to occur for several years at gradually decreasing rates.”

Operations were paused after that quake; they briefly resumed for a proposed test run in April of 2020, but have been suspended since May of 2020. The 2021 seismic report says 356 earthquakes were recorded in the Paradox Valley monitoring network in 2021; experts determined that 353 of them were caused by brine injection activities, even though they’d been suspended since spring of the previous year.

Two earthquakes on May 31 of this year in Thompson Springs, 57 miles from the Paradox Valley Unit, are not related to injection operations, Liff said.

This year’s test run “will consist of injecting brine groundwater… at a reduced rate of 115 gallons per minute, which is 67% of past operations,” the Bureau of Reclamation press release says. “Modeling indicates that this reduced rate will have a negligible impact on seismicity and Reclamation will closely monitor the injection pressure and seismic response.” If seismic activity increases in magnitude, the test run will be suspended.

Nearing capacity

The Paradox Valley Unit is nearing the end of its useful life, according to agency officials—how soon that end will come is not clear. The formation into which the facility is injecting the brine has a limited capacity and will eventually fill up. The six-month test run will, officials hope, give a clearer picture.

“The injection test results will be used to evaluate well performance and create a plan for potential future injection scenarios,” Liff said. When the well reaches its capacity, she said, it will be decommissioned.

In 2020 the Bureau of Reclamation published a draft environmental impact statement offering a suite of alternatives for how to proceed once the Paradox Valley Unit reaches the end of its life. [See “Aging infrastructure affecting the Dolores River,” Jan. 30, 2020 edition. -ed.] Alternatives included taking no action; building a new injection well facility in another location in the valley; using evaporation ponds to dry out the salt and then dispose of it; or using a technology called zero-liquid discharge, in which the brine would be piped to a plant that would crystalize the salt and return the water to the Dolores River. In the final EIS, the bureau identified Alternative A—no action—as its preferred option.

“If no other salinity control measures are implemented at Paradox Valley, salinity levels will begin to increase in the Colorado River system,” Liff said. “If no other salinity control measures are implemented at Paradox Valley, projects in other areas will be pursued to reduce the salinity impacts and concentrations downstream.”

Part of a bigger picture

Moab resident John Weisheit has been an activist working for sustainable management of the Colorado River for decades, and he co-founded a nonprofit called Living Rivers. That organization, along with other nonprofit advocacy groups, submitted a letter to the Bureau of Reclamation in 2020 during the public comment period on the agency’s draft environmental impact statement. The letter said the bureau should consider a broader-scope environmental impact statement rather than focusing only on the Paradox Valley Unit alone; the problem of salinity in the Colorado River, the letter argues, arises from too much human consumption and development, and from climate change.

“The current water management scheme works against laws of nature and, in time, will be forcefully corrected,” the letter says. “…Reclamation must accept the need and purpose to conduct a basin-wide programmatic Environmental Impact Statement that carries a theme of self-correcting all the system imbalances.”

One way the agency could address salinity, the advocates argued, would be to release more water into the Dolores River from McPhee Reservoir, a human-made facility with 381,195 acre-feet of capacity that diverts water from the Dolores River upstream of the Paradox Valley Unit to serve farmers, the Ute Mountain Ute Tribe, the Montezuma Valley Irrigation District, and other users. McPhee also releases water downstream to support fisheries and conducts controlled releases during the run-off season.

“Reduced flows lead to higher concentrations of salinity in all river systems, which has especially compounded the salinity issue for the Dolores River,” the letter says.

The increased salinity in the Dolores River is clear on the ground, according to Cody Perry, a Grand Junction-based filmmaker working on a documentary about the Dolores River and surrounding landscape. He recently floated the Dolores River (or hiked it, where there’s too little water to travel by boat) and passed by Paradox Valley. He said the salt in the river channel is tangible.

“You can smell it in the air, you can see salt crystals,” he said. He also noticed rocks that had tumbled down cliffs and hillsides during seismic events.

“It’s an inescapable physical attribute of the river down there. You see it, you touch it,” Perry said, describing a “bathtub ring” of salt on either side of the river because of reduced flow. River advocates said in 2020 that the Bureau of Reclamation should dilute that salt by directing more water back into the Dolores.

“Reducing the volume of the inter-basin diversion from the Dolores River to the San Juan Basin,
and increasing the quantity of water released downstream, would supplement Reclamation’s
action towards reducing salt loads in Paradox Valley,” the 2020 public comment letter from river advocates says.

To accommodate increased downstream releases while still serving reservoir users, the advocates suggested the bureau should look to reclaim lost water by constructing more efficient delivery systems to reservoir users.

The McPhee Dam was completed in the 1980s; Weisheit said the Bureau of Reclamation should never have built it. It’s a temporary fix to a water scarcity problem, he said, but in turn it exacerbated the salinity problem—and it doesn’t address the larger issues of overconsumption, climate change, and disjointed, short-sighted planning.

“The way the Colorado River is managed is wrong—it won’t get us through the 21st century without major overhaul,” Weisheit said.

If the six-month trial run of the Paradox Valley Unit is completed, the Bureau of Reclamation will conduct a seismic risk analysis in 2023 and develop its next operations plan. Releasing more water into the Dolores River is not included among the salinity control options in the bureau’s environmental impact statement—Weisheit said he was told the suggestion was outside the scope of the project. Sooner or later, the Paradox Valley Unit will be decommissioned and the natural salts will again flow back into the Colorado River, prompting the need for salinity control action elsewhere.