The spill that sent a yellow-orange sludge from an abandoned Colorado gold mine into the Animas River is three times as large as first thought, the Environmental Protection Agency said.
An EPA supervised crew accidentally breached a debris dam Wednesday, triggering the spill. Three million gallons of wastewater spilled from the mine, the EPA said Sunday.
Water downstream tested for higher than normal levels of arsenic, lead and other metals.
The sludgy water seeped into New Mexico and was headed for Utah, NBC News reported.