Models For Predicting Source Water Pollution: Hopelessly Flawed?

Newly public predictions about potential source water contamination are casting doubt on models used to anticipate how polluted water may flow from mining operations.

The problem centers in Minnesota, where a proposal for the state’s first copper-nickel mine has remained under environmental review for a decade. Predictions recently made public show that the proposal from PolyMet Mining Corp. could threaten a wilderness area administered by the U.S. Forest Service known as the Boundary Waters Canoe Area Wilderness (BWCA).

“While the flow of water at issue could be relatively small, and wouldn’t occur for decades, environmentalists and Indian tribes say the miscalculation is an indication that the computer modeling used to project the mine’s environmental risk to water is badly flawed,” according to the Star Tribune of Minnesota.

“The Minnesota Department of Natural Resources, which is leading the project’s environmental review, said...that it is evaluating the scenario. It was only brought to its attention recently,” the report said, citing the agency.

Kathryn Hoffman, an attorney with the nonprofit law firm Minnesota Center for Environmental Advocacy, expressed frustration with the potentially flawed predictions.

“How, after 10 years of study, can we not know which way the water is going to go? It suggests that there is a lot we don’t know about the impact,” she said, per the Tribune. “The Clean Water Act should not be a race to the bottom. If you have a pristine watershed, you have to keep it that way.”

The Tribune summarized the heart of the concerns:

Arguments detailed in technical documents obtained through the Minnesota Data Practices Act show just how difficult it is for engineers to predict the flow and quality of water that could emerge after decades of mining alter the landscape in one of Minnesota’s wettest areas. And they raise a specter that conservationists and canoeists in Minnesota have long feared: that the nearly pristine watershed that contains the BWCA will be harmed by PolyMet’s mine.

Jon Cherry, president and CEO of PolyMet Mining, says the concerns are unfounded and that the wilderness areas will not be harmed by the proposed operation.

“The reality is, existing field data from monitoring wells and surrounding lake elevations strongly support the conclusion that project groundwater will not move through the bedrock toward the Boundary Waters. All water quality and quantity data, as well as modeling analyses in the environmental-impact statement used to determine the impacts of the NorthMet project, are appropriate and adequate,” he said in a Tribune editorial.

He added that his company is taking safety precautions to protect the environment.

“Even though it is unlikely that groundwater would ever flow north toward the BWCA, PolyMet has already proposed to implement proactive measures to ensure that water does not flow north. New monitoring wells will be installed before operations begin, which would allow for more than 10 years’ worth of additional data collection prior to any potential for a northerly flow to occur,” he wrote.

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