A uranium mining company near the Grand Canyon is challenging the findings of a new study alleging that it has been removing vast quantities of groundwater containing potentially dangerous levels of arsenic.
The Grand Canyon Trust, a nonprofit conservation organization, identified three of the four sites with the highest average arsenic readings in Arizona’s Grand Canyon region as monitoring wells at the Pinyon Plain uranium mine.
Arsenic is a naturally occurring toxic metal. Long-term exposure to excessive amounts through drinking water can increase the risk of cancer and cause other serious health problems.
The US Environmental Protection Agency sets the drinking-water limit for arsenic at 10 micrograms per liter. Average readings in the mine’s monitoring wells were nearly twice, almost three times and six times that threshold.
The mining company’s own reports also showed that water collected at the bottom of the mine shaft contained arsenic levels more than 3,000 times higher than the EPA’s safe limit.
Since 2016, Pinyon Plain uranium mine—located fewer than nine miles from the Grand Canyon’s South Rim—has pumped tens of millions of gallons of groundwater from its deep shaft to allow mining operations to continue.
The water is drawn from an underground rock formation known as an aquifer. Some scientists have warned that the pumping could help move arsenic into Havasu Creek, the sole water source for the nearby Havasupai Tribe.
If arsenic-contaminated water reaches springs along the southern rim of Grand Canyon National Park, it could threaten local ecosystems as well as water supplies used by visitors and park facilities.
Concerns over arsenic pollution grew after groundwater testing found unsafe readings at an Arizona uranium mine
Monitoring wells at the Pinyon Plain uranium mine recorded arsenic concentrations two to six times above the drinking-water limit
Energy Fuels Resources Inc owns and operates the Pinyon Plain uranium mine near the Grand Canyon.
Independent groundwater specialists and hydrogeologists examining water movement in the region have said the mine’s pumping may be causing or intensifying the elevated arsenic levels detected at the site.
Hydrologist David Kreamer said the mine shaft may have intersected an aquifer, prompting the company to remove millions of gallons of water. According to his theory, cracks in the rock allowed oxygen to enter and released high concentrations of arsenic that had been naturally trapped underground.
Dr Laura Crossey, an emerita professor at the University of New Mexico, said: ‘There’s no question that there is a risk to the groundwater.’
Energy Fuels rejects the claim that its mining activity is responsible for the rising arsenic readings. The company says the levels reflect natural conditions in the mineral-rich region and that pumping is drawing in arsenic-laden water that was already present underground.
Our News Outlet has contacted Energy Fuels for comment.
Misael Cabrera, Energy Fuels’ senior vice president of environment, safety and sustainability, told Inside Climate News: ‘We don’t get to choose where we put a mine.’
‘Despite all of the evidence that we have on record, despite all of the regulatory approvals, despite the multiple court cases, we are still being assumed to be guilty before proven innocent.’
The Grand Canyon Trust’s analysis examined groundwater records from 40 wells collected between 1993 and 2025
MUST READ: Photo Shows Pilot of Doomed Florida Private Jet
Officials with the Arizona Department of Environmental Quality have accepted the company’s explanation and allowed arsenic limits in the monitoring wells to exceed the levels generally used as health standards.
The Grand Canyon Trust reviewed 32 years of groundwater records, covering data gathered from 40 wells and springs in the region’s Coconino Aquifer between 1993 and 2025.
The analysis found that arsenic concentrations in the southern monitoring well were nearly double the EPA drinking-water limit.
Readings at the northern well were just below three times the limit, while the eastern well recorded levels six times higher than the amount considered safe for drinking water.
Kreamer, an emeritus professor at the University of Nevada, said that if the company’s explanation were accurate, arsenic concentrations in the surrounding groundwater should be declining rather than increasing.
‘The mine’s argument right now is that natural background arsenic is being drawn in and that is what is creating the high and increasing arsenic levels,’ he said in a statement.
He also noted that arsenic concentrations outside the mine are 20 to 30 times lower than those measured inside the wells.
‘If arsenic concentrations in groundwater outside the mine are lower than inside, how can drawing low concentration outside increase the already high and increasing arsenic concentrations inside the property?’ Kreamer added.
The Havasupai Tribe protested the Pinyon Plain Mine in 2024, warning that it could threaten drinking water and sacred sites
Dr Brad Esser, a retired environmental radiochemistry researcher at Lawrence Livermore National Laboratory, accused Arizona regulators of approving the higher arsenic threshold without conducting sufficient testing or investigation.
‘This is a kind of a failure of the monitoring program, the regulatory process, because at the present time, we don’t really know why the arsenic is rising because it hasn’t been thoroughly investigated,’ he said.
The Arizona Department of Environmental Quality told Our News Outlet that its scientific review concluded the Pinyon Plain Mine was not introducing additional arsenic into the groundwater.
ADEQ said the mine’s operations had created what it described as a ‘hydraulic sink,’ a process comparable to water flowing toward a drain.
According to the agency, the effect draws nearby groundwater containing naturally occurring arsenic toward the mine. ADEQ said the water is collected and held in a closed system, preventing it from contaminating surrounding aquifers.
‘ADEQ’s decisions are strictly data-driven and rooted in a thorough technical analysis that considers all relevant available data, as well as over four years of extensive site-specific hydrogeological monitoring, updated modeling, and independent testing,’ ADEQ said in a statement to Our News Outlet.
The Grand Canyon Trust says the deeper Redwall-Muav Aquifer, beneath the mine, ‘feeds seeps and springs in the Grand Canyon.’
A separate groundwater study published in 2024 identified the possibility that contamination linked to the mine could reach springs along the South Rim of Grand Canyon National Park and Havasu Spring.
Havasu Spring supplies Havasu Creek, the only water source for the approximately 600 residents of Supai Village. If the spring were contaminated with dangerous arsenic levels, the Havasupai Tribe would have no alternative supply for drinking, cooking, farming or other daily needs.
