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When engineers installed the Paradox Valley Salinity Control project in 1996 on the lower Dolores River in Southwest Colorado, the result was improved water quality in the nearby Colorado River and for millions of people and farms downstream.

But an unintended consequence of pumping briny fluid deep underground has been thousands of human-induced earthquakes.

The largest was a 4.5 magnitude quake on March 4, about a mile from the injection well, that was felt in Moab, Dove Creek, Cortez and Towaoc. The injected brine was the likely cause, according to seismologists.

After the record-breaking earthquake for that area, the Bureau of Reclamation salination injection well facility was shut down on a temporary basis to allow for further study.

Draft EISThis month, a Draft Environmental Impact Statement analyzing alternatives for continued salinity control at the location was released. Comments are being taken until Feb. 4. Those interested may submit comments by email to paradoxeis@usbr.gov, or to Ed Warner, Area Manager, Bureau of Reclamation, 445 West Gunnison Ave., Suite 221, Grand Junction, CO 81501.

Two public meetings will be held: at 5 p.m. Jan. 14 in Paradox at Paradox Valley Charter School, 21501 6 Mile Road; and at 6 p.m. Jan. 15 in Montrose at Holiday Inn Express & Suites, 1391 S. Townsend Ave.

According to the EIS, “Because the underground reservoir pressure and induced seismicity have increased, and brine disposal rates have had to be substantially reduced in response, a new brine control and disposal facility is needed.”

At the Reclamation facility near Bedrock, a series of nine wells draws up the briny groundwater prevalent in the Paradox Valley, known for salt deposits left over from an ancient shallow sea.

It is piped to a nearby injection well that sends the salt water 2.9 miles underground to the Mississippi Leadville Formation.

The Dolores River is a tributary of the Colorado River. By removing the natural salt loading in the Dolores River, water quality is improved on the Colorado for an estimated 40 million people downstream, including municipalities, 5.5 million acres of farms, industry, and for communities in Mexico.

The facility has been intercepting and injecting about 95,000 tons annually of brine into the injection well. The proposed alternatives are seeking comparable amounts to be removed, and would federal government funded.

The injected brine fluid is known to cause earthquakes by adding lubrication and pressure to fault lines. An estimated 6,000 mostly smaller earthquakes are thought to be caused by the Paradox injection well since the 1990s, according to government reports and seismologists.

After a 4.0 magnitude earthquake hit in 2013 in the vicinity of the injection well, the facility reduced injection volume to try and minimize induced earthquakes.

The big oneBut when the 4.5 magnitude hit six years later, Reclamation officials decided to shut down the injection well temporarily, said Lesley McWhirter, an environmental planner for the Bureau of Reclamation.

Well pressure is reaching permit threshold standards, an indication that the total capacity of the Leadville formation site storing the brine has been reached, she said.

The EIS proposes several alternatives, including no action, a new nearby injection well, a surface evaporative system, and a zero-liquid discharge brine crystallization system. Alternatives have a goal to last 50 years.

“The Paradox Valley Unit is a cost effective salinity control project in the Colorado River Basin as it prevents 95,000 tons of salt annually from reaching the Dolores River and eventually the Colorado River – that’s approximately 7% of total salinity control occurring in the basin,” said Ed Warner, Area Manager for Reclamation’s Western Colorado Office. “Reducing salt in the rivers improves water quality, crop production and wildlife habitat in the basin.”

Seismologist explainsWhen fluids are injected deep underground consistently in one location, there is a strong potential for earthquakes to occur, said seismologist Jim Pechmann, of the University of Utah Seismograph Station.

“We know there is a cause and effect there, especially if injection has been occurring over a long time such as the Paradox injection well site,” he said. He said that there is “really no doubt” that the large March 4 earthquake was induced by the brine injection.

Industrial injection wells are know to cause earthquakes in areas that are not known for them naturally such as in Oklahoma, Texas, and Southwest Colorado.

Fluids pumped deep underground create pressure against ancient fault lines, which become lubricated and slip, causing earthquakes, Pechmann said. “The more the fault gets pressurized, the bigger the magnitude,” he said. “Old faults that have not been active for millions of years have zones of weakness that can slip under the added pressure. There are always old faults around.”

Rock layers with porous features that allow the brine fluid to flow away from the injection well and not build up pressure would help minimize the potential for earthquakes, Pechmann said.

Alternatives priced at $99 million and upThree alternatives and a no action option have been proposed:

Alternative B1, B2: Cap the current injection well and install a new well nearby in the Paradox Valley. Initial studies indicate the proposed new well sites have a Leadville formation with less faults and more space that would be less susceptible to induced earthquakes. They are a greater distance from population areas, and would reduce the level of shaking experienced by residents. One of the sites would require two new bridges across the Dolores River. The costs of the wells, and associated pipelines and pump stations, would be between $99 million and $116 million, and operations and maintenance would create 20-23 jobs. Three-dimensional seismic geologic investigations would be completed to finalize the most ideal location.Alternative C: Brine would be collected from the existing brine production well field and piped to the existing surface treatment facility. Then it would be piped to a series of evaporation ponds seven miles southeast of the production well field. The facility would be operated to evaporate the water from the brine, thereby allowing the solid salt to be harvested for disposal in an onsite salt landfill, or to be used as a commodity.The conceptual pond system design includes a 27-acre surge pond, a 39-acre concentrator pond, 290 acres of crystallizer ponds, 24-acre bittern concentration pond, and a 10- acre-foot bittern storage pond. A hydrogen-sulfide treatment system would be included to remove H2S before brine is discharged to the evaporation ponds. Ponds would be netted according to FWS specifications to restrict access by birds and small mammals and to allow for snow loading.

Salt would be harvested from the evaporation ponds and disposed of in a 60-acre, onsite salt landfill. The salt landfill would reach a vertical height of 100 feet above the ground surface. Estimated construction cost is $132 million. Operation and maintenance would create 20 jobs.

Under Alternative D, brine would be collected from the existing brine production well field and piped to the surface treatment facility. Then it would be piped to a centralized treatment plant, consisting of a series of thermally driven crystallizers. The zero-liquid discharge facility would be operated to evaporate (and later condense) water from the brine, resulting in a solid salt and produced freshwater stream. The solid salt would be transported to an onsite, 60-acre salt landfill. Estimated construction cost is $112 million. Operations and maintenance would generate 157 jobs.jmimiaga@ the-journal.com