Updated Oct. 4 with details on the contamination source — The Missouri Department of Natural Resources has identified a paving company as the source of the white contamination that appeared in Coldwater Creek over the weekend.
In a statement released Tuesday, the state agency said an accident caused a truck carrying a chemical called Modifier A/NA, an additive used to make concrete, to spill the product into the creek. The St. Peters-based Pavement Solutions was responsible for transporting the chemical.
The concrete additive has low toxicity to humans and aquatic life, according to a Materials Safety Data Sheet for the product.
As a result, state officials have issued an order to Pavement Solutions to immediately clean up the contamination. The company is using vacuum trucks to remove tainted water.
State officials began testing water samples from Coldwater Creek on Sunday, after residents observed that the creek turned white.
The Missouri Department of Natural Resources contacted the Metropolitan Sewer District to investigate any connection to the sewer system, but the sewer district could not immediately determine the cause of the discoloration.
"Our experience, when we find something like this is that it's some sort of illegal dumping or discharge," MSD spokesman Lance LeComb said Monday. "It could be as simple as someone dumping paint or something similar into a storm drain or directly into the creek."
The Army Corps of Engineers has been cleaning up World War II-era radioactive contamination around Coldwater Creek for several years. The federal agency took authority of the Coldwater Creek site in 1998.
"We've been working in the creek now for quite a few years, so if our processes, if any of the sampling or remediation had any kind of effect, we would have seen it by now. It would have been happening already," said Amanda Kruse, spokesperson for the Army Corps of Engineers' St. Louis district.
The site has been under much public scrutiny in recent years, as residents have become concerned that exposure to radioactive contamination around the creek caused multiple cancer cases in the area. The federal Agency for Toxic Substances and Disease Registry began surveying area residents about their health issues last winter.
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