1 year after spill, officials say Dan River is recovering as fines against Duke are considered

FILE - In a Wednesday, Feb. 5, 2014 file photo, Duke Energy engineers and contractors survey the site of a coal ash spill at the Dan River Power Plant in Eden, N.C. as state and federal environmental officials continued their investigations of the spill into the river. A year after the sudden collapse of an old drainage pipe triggered the third largest coal ash spill in U.S. history, regulators say they are still working to determine how much to fine Duke Energy, the nation’s largest electricity company. (AP Photo/Gerry Broome, File) (The Associated Press)

In this Wednesday, Feb. 5, 2014 file photo, signs of coal ash swirl in the water in the Dan River in Danville, Va. A year after the sudden collapse of an old drainage pipe triggered the third largest coal ash spill in U.S. history, regulators say they are still working to determine how much to fine Duke Energy, the nation’s largest electricity company. (AP Photo/Gerry Broome, File) (The Associated Press)

RALEIGH, N.C. – A year after the sudden collapse of an old drainage pipe triggered the third largest coal ash spill in U.S. history, regulators say they are still working to determine how much to fine the nation's largest electricity company.

Records show past fines levied after large coal ash spills in other states ran into the millions of dollars.

It took nearly a week to plug the leak that coated 70 miles of the Dan River in gray sludge.

A key issue in assessing what Duke Energy will eventually pay depends on what, if any, long-range damage was done to the river.

So far, Duke says recent studies show the river is recovering.

But scientists and environmentalists warn it could take years before the true impact on the river's ecosystem is known.