COON RAPIDS, Minn. — State agencies are still working to identify a potential source after people reported seeing a sheen on the Mississippi River near Coon Rapids earlier this week.
The Minnesota Pollution Control Agency (MPCA) said a sheen was reported Tuesday afternoon at the Highway 610 Bridge in Coon Rapids, and another was reported Wednesday morning near West Coon Rapids Dam Regional Park. It's unclear if the second sheen is connected to the one reported on Tuesday.
The MPCA confirmed that the Minnesota Department of Health is conducting water tests to determine if the substance was hazardous. As of Thursday afternoon, those tests showed negative results.
"Thus far all the samples tested by MDH's Public Health Lab have come back negative for substances which would pose a threat to the safety of municipal drinking water systems," MPCA Communications Manager Michael Rafferty said in a statement.
According to the MPCA, the first report came from the Fridley Fire Department around 1 p.m. Tuesday. The sheen was seen at the Highway 610 Bridge and was traveling downstream. Officials have not yet identified the substance.
"Crews on site deployed booms to divert the sheen away from city water intakes in Minneapolis and St. Paul," Rafferty said in a statement Wednesday. "They also gathered numerous samples from the river and the Minnesota Department of Health is analyzing those samples; results are expected early Thursday."
A second sighting of a smaller sheen was reported around 8 a.m. Wednesday near the West Coon Rapids Dan Regional Park.
A spokesperson with the City of Minneapolis said they briefly shut down the intake portals from the river on Tuesday afternoon to prevent any potential contamination.
"The City maintains a large volume of finished water storage and continued to supply Minneapolis and wholesale customers with fully treated drinking water while intakes were shut," the spokesperson said in a statement. "Intakes reopened Wednesday morning after additional testing showed no toxicity in the river water at the point of intake."
The spokesperson went on to say the treatment plant has been operating continuously with added precautions.
A St. Paul Regional Water Services spokesperson said they also shut down the intake pumping station at Fridley on the Mississippi River, "preventing flow from reaching the chain of lakes within our surface water supply."
According to the MPCA, the most common sheens are either bacterial or petroleum, which can typically be distinguished by how they're broken up.
"When a stick is poked into a bacterial sheen or a stone is dropped into it, the sheen will typically break into small platelets," the MPCA posted on its website. "In contrast, a petroleum sheen will quickly try to reform after any disturbance."