The city public works department said on April 21 that the sheen on the Missouri River near the city’s wastewater treatment plant was no longer present.

On April 19, the city and Calumet Refining jointly responded to a reported sheen along the Missouri River with absorbent materials, booms, as a precautionary measure.

The sheen was near the wastewater treatment plant’s sanitary sewer outfall on the river.

City, Calumet responding to sheen on river

City public works said on April 21 that tests indicated the plant was operating and functioning under normal conditions and that the source of the sheen was exterior to and outside the control of the plant.

City staff are continuing to collect samples and conduct analysis to determine any necessary corrective action.

In a release, Calumet said the area experienced a winter storm that resulted in considerable snow melt.

Absorbent booms were placed near the plant to mitigate any potential storm impacts, according to Calumet, and the company would monitor for any changes.

Calumet containing sheen on Missouri River [2017]

Calumet provided mutual aid support to the city by sending members of the company’s spill response team to help manage any potential impacts neat the city plant.

“We are committed to being a responsible member of our community,” Carlos Centurion, Calumet plant manager, said in a release. “We will continue to closely monitor the river near the plant to manage potential impacts from the storm event. We are also pleased that we were able to work with the City of Great Falls and provide mutual aid when needed.”