"We know we have likely more than 100,000 [abandoned mine] sites on public lands alone. And we don’t know -- because we’ve not yet had the opportunity to inventory -- the risk that may be present," said Interior Secretary Sally Jewell in congressional testimony Wednesday.
Jewell says her department does know that in the area around the Gold King mine, there are some 400 other abandoned mine sites where water is building up and leaking a total of more than 300 million gallons a year.
"We’re learning about the lack of clear standards with regard to the engineering aspects of these mines and I think those are lessons that we take away from this that will make us more effective land managers involved in cleaning up these things that we did not cause, but we now have responsibility for," Jewell said.
The blowout at the Gold King Mine in August spilled 3 million gallons of contaminated wastewater into the Animas River.
Editor's Note: The headline on an earlier version of this story incorrectly identified Sally Jewell as head of the Environmental Protection Agency. She is Secretary of the Interior.