Tennessee American Water has yet to detect any signs of mercury in the Tennessee River following a spill of 50 pounds of the poisonous substance from the Olin Chemical plant in Bradley County.
Tropical Storm Lee's 12.7 inches of rain last week caused the plant's treatment lagoon to overflow, sending the contaminant into the river.
However, Tennessee American's new president, Deron Allen, said no contamination has been found either by the Chattanooga utility or by Eastside Utility District, both of which check the water several times a day.
The large volume of water flowing through the river every day may have simply dispersed the mercury to undetectable levels, he suggested.
"We have not had any detection of any of that," he said. "We'll keep checking until the [Tennessee Department of Environment and Conservation] tells us to stop."
The spill was small, Allen said, especially compared to previous spills that sounded worse than they were later found to be.
"You hear that there's 50 pounds of mercury spilled, and all you hear is 'mercury spill,'" Allen said.
Instances of contaminants simply disappearing into the river are not unusual, said John Watson, former president of Tennessee American.
After TVA spilled 130 million tons of coal ash, the utility checked the water for 120 days and "never found anything," Watson said.