State and local officials, and the company allegedly at fault for the incident, said they still don't know how more than 1,000 gallons of oil from the Norfolk Southern deButts Yard ended up in Citico Creek and the Tennessee River.
An oil spill Monday night dumped the product into the creek, leading emergency responders to flock to the area to contain the spill. Officials point to Norfolk Southern as the culprit, and a Norfolk spokeswoman said the company believes it may be responsible for the incident.
"We are still investigating the cause of the release," company spokeswoman Susan Terpay said. "I will update you with more information as soon as it is available."
Meanwhile, the portion of the Tennessee Riverwalk that was closed during the investigation has reopened.
The Tennessee Department of Environment and Conservation is leading the investigation and its investigators believe the oil came from a retention pond on the property, according to TDEC Deputy Communications Director Kim Schofinski. The agency is conducting an investigation into the incident and will issue a report on its findings.
The Environmental Protection Agency sent a coordinator to the scene at the request of TDEC to assist. The city's role in the cleanup, which included initial response and work to contain the oil, is complete, according to fire department public information officer Bruce Garner.
The spill could have a significant impact on the ecosystem, according to Tennessee Aquarium aquatic conservation biologist Bernie Kuhajda.
The oil mostly sits on the top of the water, allowing multiple animal species including fish, birds and turtles to come in direct contact with the oil.
Norfolk Southern is taking significant steps to ensure the incident is contained as much as possible and appropriately cleaned, Terpay said.
"We had 120 contractors and environmental specialists working along Citico Creek and the Tennessee River [Thursday] collecting and removing the oil-water mix from the waters," she wrote in an email. "On the Tennessee River we used on- water booming to assist in the recovery and continued recovery operations at Citico Creek, as well as clearing debris and other land cleanup efforts."