BOISE, Idaho (AP) — A giant aquifer below an eastern Idaho federal nuclear facility is as free of radioactive contamination and other pollutants as it has been in more than six decades of monitoring but the water level of the aquifer is at its lowest ever recorded, according to a U.S. Geological Survey report released this week.
Better environmental practices and cleanup work at the 890-square-mile (2,305-square-kilometer) U.S. Department of Energy site that includes the Idaho National Laboratory is paying off, said United States Geological Survey scientist Roy Bartholomay.
"Overall the aquifer is better quality than it has been at the Idaho National Lab," Bartholomay said. "There are just some anomalies out there we want to keep an eye on."
The federal site built in high-desert sagebrush steppe opened in 1949 and includes various components. Among them is a U.S. Navy site that handles fuel waste from the nation's fleet of nuclear-powered warships and the Idaho National Laboratory, considered the nation's leading nuclear research lab.
The report released Monday is based on samples taken over a four-year span ending in 2015 from the Eastern Snake Plain Aquifer that supplies water to cities and farms in the region. The drop in water level to a record low occurred in 2016.
Officials say contamination from the federal site reached the aquifer through injection wells, unlined pits and accidental spills, mainly during the Cold War era before regulations to protect the environment were put in place.
In 1972, about 19,000 gallons (71,920 liters) of highly radioactive sodium bearing waste that involved the tritium, strontium-90, cesium-137 and plutonium-238 spilled during a failed underground transfer at the Idaho Nuclear Technology and Engineering Center's tank farm.
The U.S. Department of Energy has spent millions of dollars cleaning up various areas of the facility that is listed as a superfund site. That includes digging up buried waste and sending it to a New Mexico facility.
"From what's been going on all these years from a cleanup perspective, yes, we are accomplishing our goals," said Daryl Koch, who manages the state's participation with the Idaho Department of Environmental Quality in monitoring federal cleanup efforts.
The U.S. Geological Survey monitors 177 wells, most within the boundaries of the federal site. It takes from 50 to 700 years for water to travel through the aquifer and emerge in springs near the small city of Twin Falls.
A key finding in the report was a decrease of a substance used as a cleaning solvent associated with nuclear material at the Radioactive Waste Management Complex, where nuclear waste from around the country was buried for decades, Bartholomay said.
Nolan Jensen, who a leads Department of Energy team working on the cleanup, said in a statement he was pleased with the findings and that the contamination levels "are well-below regulatory targets."
On the troubling side, Bartholomay said, was an increase in nitrate near the tank farm area. He said the cause is not clear.
Although not part of the report, the water level in the aquifer reached a new low of 596 feet (182 meters) below the surface in 2016, down about 14 feet (4.3 meters) in just more than two decades.
Melting of heavy mountain snowpack expected this year could help the aquifer's level rise about 2 feet (0.6 meters), Bartholomy said.