The records show that at average flows, more than 50 million gallons of contaminated wastewater streams daily from the sites.
In many cases, it runs untreated into nearby groundwater, rivers and ponds — a roughly 20 million-gallon daily dose of pollution that could fill more than 2,000 tanker trucks.
The remainder of the waste is captured or treated in a costly effort that will need to carry on indefinitely, often with little hope for reimbursement.
The volumes vastly exceed the release from Colorado’s Gold King Mine disaster in 2015, when a U.S. Environmental Protection Agency cleanup crew inadvertently triggered the release of 3 million gallons of mustard-colored mine sludge, fouling rivers in three states.
At many mines, the pollution has continued decades after their enlistment in the federal Superfund cleanup program for the nation’s most hazardous sites, which faces sharp cuts under President Donald Trump.
Federal officials have raised fears that at least six of the sites examined by AP could have blowouts like the one at Gold King.
Some sites feature massive piles or impoundments of mine waste known as tailings.
A tailings dam collapse in Brazil last month killed at least 169 people and left 140 missing.
A similar 2014 accident in British Columbia swept millions of cubic yards of contaminated mud into a nearby lake, resulting in one of Canada’s worst environmental disasters.
In mountains outside the Montana capital of Helena, about 30 households can’t drink their tap water because groundwater was polluted by about 150 abandoned gold, lead and copper mines that operated from the 1870s until 1953.