The City of Great Falls received analytical results associated with the sheen on the Missouri River at the sanitary sewer outfall that occurred on April 19.

The results indicated elevated levels of oil and grease in the city’s collection system as well as at the city’s wastewater treatment plant, according to the city.

These levels are not typical and were determined to be from an external source.

City, Calumet update sheen response

The city has initiated required enforcement actions and will follow applicable procedures, per requirements from the U.S. Environmental Protection Agency and the Montana Department of Environmental Quality, according to the city public works department.

Results from the sample taken in the Missouri River did not exceed the city’s allowable discharge limit and did not result in enforcement exposure as it pertains to city’s Montana Pollutant Discharge Elimination System Permit, according to the city.

City, Calumet responding to sheen on river

This incident is related to the sanitary sewer outfall not the storm sewer outfall, where Calumet currently has placed approximately 30 feet of booms and absorbent materials, according to the city.