Members of three activist groups say recent research shows that abandoned uranium mines are contributing to elevated uranium levels in Angostura Reservoir in the southern Black Hills.
The research was recently published in the journal Environmental Earth Sciences by authors that included two South Dakota School of Mines & Technology scientists, Rohit Sharma and James Stone. The article is titled “Stream sediment geochemistry of the upper Cheyenne River watershed within the abandoned uranium mining region of the southern Black Hills.”
According to the Clean Water Alliance, Dakota Rural Action and It's All About the Water, the research shows that elevated uranium levels at Angostura are partly caused by human activity, including abandoned uranium mines and a former mill at Edgemont. Elevated uranium levels at Angostura Reservoir are comparable to the elevated uranium levels upstream in the Cheyenne River watershed at abandoned mines, the groups said.
“This impacts people throughout western South Dakota,” Gena Parkhurst, president of the Black Hills Chapter of Dakota Rural Action, said in a news release. “The Cheyenne River runs along or through two reservations and five counties. It impacts agriculture and tourism. We need to clean it up.”
The groups cited U.S. Environmental Protection Agency reports that list 169 old uranium mines and prospects in the southern Black Hills, which was mined for uranium from 1951 to 1972. Few of the old mines have been cleaned up. Additionally, the groups said there was a 1962 dam break that released uranium mill wastes into the Cheyenne River, and some of the wastes reached Angostura, a popular recreation spot.
The groups are using the research to call upon state and federal regulators to clean up old mine sites. The EPA studied several abandoned mine sites north of Edgemont last year and determined that although the sites contained pollutants, there had not been a release of the material that was sizable enough to necessitate a cleanup.
Lilias Jarding, of the Clean Water Alliance, said the recent research by the Mines scientists shows otherwise.
“These radioactive mines have been sitting open for as much as 65 years,” Jarding said in the news release. “These test results make it clear there is a problem that threatens public health and demands immediate action.”
Aside from the concerns about abandoned historical mines in the Edgemont area, a proposal to conduct a new kind of uranium mining in the same area is pending from Azarga Uranium Corp. Instead of digging tunnels and open pits as past mining operations did, Azarga wants to conduct in situ mining, which involves injecting a solution of water, oxygen and carbon dioxide to leach uranium from underground ore before pumping it to the surface.
Uranium is a naturally occurring radioactive element that was mined historically for use in nuclear weaponry and is now mined for nuclear power generation. Naturally occurring uranium in rock form is not typically hazardous, because the skin blocks uranium's alpha-particle radiation. But if uranium particles are ingested in high concentrations via air or water, they can cause cancer.