Crews are returning to the scene of a massive mine waste spill in southwestern Colorado to stabilize the mine opening with steel bracing and concrete.
The Environmental Protection Agency said Friday work at the Gold King Mine will begin this weekend and last through October.
An EPA-led contractor inadvertently triggered a spill of 3 million gallons of wastewater from the Gold King last August while doing preliminary cleanup work.
The spill tainted rivers in Colorado, New Mexico and Utah. Water utilities shut down their intake valves and farmers stopped drawing from the rivers. The EPA says the water quality quickly returned to pre-spill levels.
The spill triggered lawsuits and intense criticism of the EPA.
The agency has proposed a Superfund cleanup of the Gold King and other nearby mining sites.