The Bureau of Reclamation restarted operations of the Paradox Valley Unit (PVU), a crucial salinity control facility for the Colorado River system. For the next six months, the PVU will operate at a reduced capacity to gather data that will help guide future operational decisions.
Located in a remote area of western Colorado, along the Dolores River in Montrose County, the PVU removes an average of 95,000 tons of salt annually from the Dolores and Colorado rivers. It does this by extracting brine groundwater in the Paradox Valley and injecting it into a deep injection well, thereby preventing it from entering the Dolores River, which is a major tributary of the Colorado River. Saline concentrations of this naturally occurring brine groundwater have measured in excess of 250,000 milligrams per liter—about eight times saltier than seawater—and have contributed up to 200,000 tons of salt per year to the Colorado River system.
Prior to the restart, the Paradox injection well had been shut down since March 2019, when a 4.5 magnitude earthquake was recorded at the site. Though there was no damage to the well or surrounding area, injection was suspended to model injection formation pressure, monitor and analyze seismic activity, and to perform a seismic hazard analysis to ensure safe operation. Reclamation has determined that seismic activity at the site has significantly decreased and that resuming operations at a reduced rate under close watch is acceptable.
“The safety of our personnel and that of the community is our primary concern,” said Upper Colorado Regional Director Wayne Pullan. “After ceasing operations of the unit and thorough inspections, we want to ensure the community that we are ready to test the site by operating the unit at a reduced capacity for continued evaluation and assessment.”
The six-month-long operational test will consist of injecting brine groundwater into the 16,000-foot-deep well at a reduced rate of 115 gallons per minute, which is 67% of past operations. 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 any unfavorable conditions develop, such as increased magnitudes in seismicity, operation will be suspended until it is deemed safe to continue.
“The injection test results will be used to evaluate well conditions and help Reclamation create a plan for potential future injection operations,” said Western Colorado Area Office Manager Ed Warner. “A seismic risk analysis will be completed in 2023 and an operations plan may be developed, based upon the injection test results.”
The PVU started operations in 1996 and provides substantial benefits, 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.
The Colorado River Basin Salinity Control Forum meeting was held May 11, where the Basin states participated in discussion and coordination regarding PVU operations, seismic risk analysis, and post-EIS direction, to include the start of this six-month injection well test.