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Report shows most Grand Canyon groundwater meets federal uranium standards

The Pinyon Plain Mine, formerly known as the Canyon Mine, is near Tusayan and the South Rim of Grand Canyon National Park. A new study from the U.S. Geological Survey has established a baseline for uranium concentration in groundwater for the area.
Ryan Heinsius/KNAU
The Pinyon Plain Mine, formerly known as the Canyon Mine, is near Tusayan and the South Rim of Grand Canyon National Park. A new study from the U.S. Geological Survey has established a baseline for uranium concentration in groundwater for the area.

The U.S. Geological Survey has released a first-of-its-kind study of uranium levels found in Grand Canyon National Park’s groundwater. It’s part of a long-term effort to try to determine the potential impacts of uranium mining in the area.

USGS released its findings after surveying water samples from from 180 springs and 26 wells between September 1981 and October 2020. Nearly 95% of the locations had concentrations of uranium below the federal maximum drinking water standard. The report doesn’t draw any conclusions but establishes a baseline to show possible changing water chemistry.

The highest amount of uranium was detected below the abandoned Orphan Mine on the South Rim. USGS didn’t say if it’s had a direct impact on nearby water sources and studies will continue.

A spokesperson for Energy Fuels Resources, which owns the not-yet-operational Pinyon Plain Mine near Tusayan, says the report confirms their stance that modern uranium mining is low impact, and doesn’t contaminate groundwater.

But according to the Grand Canyon Trust, the elevated levels near the Orphan Mine are a cause for major concern. The group says it could take decades or longer for uranium to show up in Grand Canyon’s groundwater and more study of the area’s complex geology is needed.

In 2012, the U.S. Interior Department under President Barack Obama banned new uranium mining claims on a million acres near the park for 20 years in part to study the impacts of uranium mining on area water.

Ryan Heinsius joined the KNAU newsroom as executive producer in 2013 and was named news director and managing editor in 2024. As a reporter, he has covered a broad range of stories from local, state and tribal politics to education, economy, energy and public lands issues, and frequently interviews internationally known and regional musicians. Ryan is an Edward R. Murrow Award winner and a Public Media Journalists Association Award winner, and a frequent contributor to NPR's Morning Edition, All Things Considered and national newscast.