U.S. scientists knew little about the impact of uranium mining in the Grand Canyon region before an Obama-era decision shut down new mining claims.
Uranium first was discovered near the national park in the late 1940s and has been subject to boom-and-bust cycles.
Mines opened as prices soared for the radioactive element used for Cold War weaponry and now nuclear power and were then put on standby or closed as prices tanked.
The 20-year ban on new mining claims went into effect in 2012 to slow the flurry of claims and over concern that a water source used by 30 million people in the West could become contaminated. The mining industry asked the Supreme Court last week to review the ban, and President Donald Trump's administration is reviewing a portion of it.
Scientists with the U.S. Geological Survey have been gathering soil samples, testing wells and springs, and collecting toads, rodents and other things to better understand mining's impact. The studies are being done under budget constraints and a Trump administration proposal to cut off funding entirely.
Here's a look at the scientists' work:
STATUS OF MINING
No sites are actively being mined within the sparsely populated 1 million-acre area north and south of Grand Canyon National Park. The closest to opening is the Canyon Mine, about six miles south of the entrance to the park's popular South Rim. The company that owns it, Energy Fuels Inc., has been digging the mine and ventilation shafts, and says it will mine it only when prices for uranium rise enough to make the effort profitable.
Others sites are being reclaimed or not yet developed.
The uranium is found in cylinder-shaped deposits of broken sedimentary rock.
At high levels of exposure, uranium can cause health problems such as cancer. It can also affect the ability of plants and animals to grow, survive and reproduce.
Scientists say they'll be able to document effects on water, soil and wildlife during the life of a mine but not necessarily at a single site.
HOW THE WATER FLOWS
Before the ban, the U.S. Geological Survey gathered historical data and found 7 percent of water samples from 430 sites had elevated levels of uranium and other metals. Hydrologist Fred Tillman said nothing showed the levels were directly tied to mining activity, even where concentrations of uranium were the highest....