Nov 19, 2014 3 min read

MORGANTOWN, W.Va. – Concentrations of iron and sulfate collecting in underground pools could pollute the Potomac River and its surrounding groundwater, according to a long-awaited environmental impact report released Wednesday.

The report from the federal Office of Surface Mining Reclamation and Enforcement assessed the North Branch of the Potomac River Mine Pool, which encompasses 12 flooded, underground mines beneath the Potomac. The Potomac, one of the Atlantic coast’s longest rivers, empties into the Chesapeake Bay, and the report said flooded mines could pose a risk to the surrounding water system as a whole.

“Iron, total dissolved solids and sulfate concentrations are the main water quality concerns for all pools” underneath the Potomac, the report says. It says those concentrations could “degrade” surface and groundwater. Managing the elevation of water in the pools “is critical in the protection of the North Branch Potomac River,” the report said. “This significant risk to the North Branch Potomac River … should be monitored closely.”

The report does not discuss effects of iron or sulfate on humans. The World Health Organization does not suggest health-based guidelines for either substance, but warns that excessively high doses of iron can be fatal and that high doses of sulfate can cause dehydration.

“There is a long legacy of coal mining and drainage issues that are always a potential problem on the Potomac,” said Hedrick Belin, President of the Potomac Conservancy in Washington, D.C. The conservancy is not affiliated with the report released Wednesday.

“We need to know where potential pollution problems are going to arise,” Belin said. “This is where a lot of our drinking water comes from.”

The Potomac River was named first on a list of the United States’ 10 “Most Endangered Rivers” in 2012 by nonprofit river conservation group American Rivers.

“The challenges faced by the Potomac represent the problems that all rivers face,” Belin said. “It’s the nation’s river.”

The authors of the report also released a separate assessment of the Fairmont Mine Pool Wednesday. The Fairmount pool comprises eight large and several smaller flooded mines underlying the Monongahela River. The Monongahela is a major drainage basin that includes more than 7,300 square miles of West Virginia, Maryland and Pennsylvania.

The Fairmount report cites iron and sulfate deposits as potential problems if water levels in underground pools rise.

The Fairmont pool “should still be monitored periodically, since an overflow or breakout of mine water would adversely affect surface water quality” in surrounding creeks or the Monongahela River,” the report said.

The Potomac River provides drinking water to about 4 million residents in the Washington, D.C., metropolitan area.

The Monongahela River provides drinking water to about 800,000 people in Southwestern Pennsylvania and northern West Virginia.

The reports do not set up monitoring plans for either mining pool, or assess costs for treatment or monitoring.