The report didn’t confirm which metals were in the waste, but researchers believe it likely contained cadmium, copper, lead, mercury, nickel and zinc. Tests done after the spill also found arsenic and lead in the wastewater.

EPA didn’t unveil which metals were in the waste, but researchers believe it likely contained cadmium, copper, lead, mercury, nickel and zinc.

Last month, New Mexico took a first step to sue EPA over the spill. Officials have yet to tally the total damage from the accident, but they accuse EPA of repeatedly failing to protect the state and its residents.

The state is also suing Colorado and the owner of the abandoned mine for their roles in the spill, which happened as an EPA clean-up crew was working at the abandoned Gold King mine.

New Mexico’s imminent lawsuit is believed to be the first formal intention to sue the EPA over the accident.

An earlier probe conducted by the US Department of the Interior concluded the spill, while avoidable, was “clearly unintentional.”

The agency has said it does not expect any negative health effects from exposure to the water and that the risk of adverse impacts to livestock is low. EPA has also said that it has not uncovered any food-safety concerns related to agricultural contamination.