Grand Canyon groundwater systems’ high interconnectivity makes nearby uranium mining risky – study

In a recent paper in the journal Annual Review of Earth and Planetary Sciences, US-based researchers state that uranium mining near the Grand Canyon’s springs and groundwater sources requires better monitoring and the application of hydro-tectonic concepts to reevaluate their viability.

The data the scientists reviewed suggest that the high level of interconnectivity of the groundwater systems in the area means that uranium mining and other contaminant activities pose risks to people, aquifers, and ecosystems. 

“This is unsurprising for anyone who has looked at the mixing of rivers, but similar processes are more hidden and incompletely understood in groundwater,” Karl Karlstrom, one of the paper’s authors from the University of New Mexico, said in a media statement. “Water flows down gradient, and fault pathways control where groundwater ponds in sub-basins. In the Grand Canyon region, these sub-basins are each vented by major springs on tribal or parkland.”

The highest-volume springs are the Havasu Spring, on the Havasupai Reservation, which supplies water for the Village of Havasupai people inside the Grand Canyon, and the Blue Spring, which is culturally significant for Navajo and Hopi peoples. Other springs emerge in parkland and provide water for the Grand Canyon’s more than six million annual visitors.

In the authors’ view, hydro-tectonic concepts are needed to understand Grand Canyon springs and groundwater wells.

“Our research efforts have utilized geologic mapping and geochemical tracers in the groundwater systems, leading us to conclude that faults act as fluid superhighways, connecting upper and lower aquifers that were once thought of as separated by impermeable layers,” Laura Crossey, lead author of the paper, said. “These concepts have wide applications and generally have been underappreciated in other global arid-land groundwater systems.”

In the case of the Colorado Plateau system, the researchers believe these concepts have significant and timely societal importance. The Pinyon Plain – formerly known as the Canyon – uranium mine, very close to the park’s South Rim Village, began extracting ore in January 2024. 

“State and Federal permitting agencies should consider all the available science,” Karlstrom said, concerning the environmental approval for Energy Fuel’s mine. “Tribes claim the permitting is ignoring recent peer-reviewed science and risks to culturally significant features.”

The researchers recommend abundant caution and no mining in this sensitive region due to the considerable contamination risk of portions of the regional aquifer system, including the very susceptible Havasupai springs that supply Havasupai Village.

Interest in uranium has surged amid a growing supply gap and increased demand as governments worldwide turn to nuclear power to counter climate change. In addition, the US is looking to ban imports of enriched Russian uranium — the kind used to fuel nuclear reactors and weapons — raising the appeal of potential local suppliers.