Uranium Concentrations in two Major U.S. Aquifers Exceeds EPA Regulations

A recent study concluded that the High Plains and Central Valley aquifers exceed the uranium contamination guidelines set by the Environmental Protection Agency and endanger roughly two million people that live above or near these water sources.

Roughly 275,000 samples were taken by University of Nebraska-Lincoln (UNL) researchers Karrie Weber and Jason Nolan. Their findings indicated that 78 percent of the uranium-contaminated sites were linked to the presence of nitrate, which is a common groundwater contaminant, according to a release.

Nitrate is commonly produced from chemical fertilizers or animal waste, and creates naturally occurring uranium through a series of bacterial and chemical reactions, which oxidize the radioactive mineral, making it soluble in ground water.

Additionally a report stated that shallow wells, roughly 30.5 meters or less in depth, are about eight times more susceptible than deep wells to exceeding EPA standards for both nitrate and uranium as a result of infiltration from runoff.

Roughly two million people live above or around the High Plains and Central Valley aquifer sites. In fact, the study concluded that many Americans live less than two-thirds of a mile from wells that are contaminated with high levels of uranium.

According to the release, the High Plains aquifer contains uranium concentrations up to 89 times the EPA standard and nitrate concentrations up to 189 times greater. The uranium and nitrate levels of the California-based Central Valley aquifer measured up to 180 and 34 times their respective EPA thresholds.

"It needs to be recognized that uranium is a widespread contaminant," said Weber, assistant professor of biological, Earth and atmospheric sciences at UNL, in the release. "And we are creating this problem by producing a primary contaminant that leads to a secondary one."

Exposure to uranium-contaminated water may lead to, or cause people to be more susceptible to, kidney damage or elevated blood pressure. In addition to affecting the area's drinking water sources, food crops can accumulate dangerously high uranium concentrations from being irrigated by contaminated water.

The High Plains aquifer is the largest in the United States, and reportedly supplies drinking water and irrigation to eight surrounding states, stretching from South Dakota through Nebraska and into northern Texas. Additionally, the Central Valley aquifer is California's largest reservoir and heavily depended on for irrigation.

Throughout their study, the researchers also noted that only one of six wells located near a former or current mining site was contaminated. This contradicts the assumption that uranium stems primarily from mining operations or spent nuclear fuel, according to Weber.

To address this issue, Weber suggests managing the groundwater supply and specifically the aquifer's sediment, since it is possible to control uranium concentrations with sediment that houses bacteria that breathes or eats it, said the release.

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