Crews have removed between 13,000 to 14,000 gallons of an unidentified oily substance from the Flint River in the week since a fisherman first reported the spill.
Containment and cleanup operations on the river are beginning to wind down.
State officials say Lockhart Chemical Company has been identified as the source of the oily material — and accepted responsibility. The company produces anti-rust additives.
But Genesse County Sheriff Chris Swanson admitted that they have still not discovered the source of the leak beneath one of the city’s industrial zones. He called it an “autopsy of the dirt.”
“Imagine 50, 75 years of piping,” said Swanson. “It’s a matrix down there.”
Swanson expects it will take time to discover the exact location of the breach. But he said the small amount of material still turning up is residual and there is not new material leaking.
Genesse County officials continue to discourage residents from fishing or coming into contact with the part of the Flint River affected by the spill.
Crews set up absorbent booms along as far as 20 miles downstream. Most of the containment and cleanup efforts have been scaled back to about a mile from the source of the spill.