Updated 5 p.m. June 22

During Tuesday’s City Commission meeting, deputy city manager Chuck Anderson updated the commission on a sheen that was reported on the Missouri River near Calumet Montana Refining on June 6. Anderson said city crews responded immediately and after determining it came from the refinery, worked with Calumet to ensure public safety.

Marlena Halko with Calumet said the release was less than a quart of hydrocarbons that got into the storm drain. According to what was reported to the Montana Department of Environmental Quality, was an estimate of 0.0046 gallons of diesel range oil.

Halko said upon notification, the company quickly found the source and stopped the flow into the river. Two booms were set up the night of June 6 as a precaution and during an inspection the next day, no materials were collected by the booms since the sheen had dissipated.

The furthest down river boom was removed the next day after inspection by state officials. The second boom was removed with approval of city officials early the next week after completion of storm water drain cleaning activities were completed, Halko said.

There is no continued leak into the storm water system, Halko said.

Anderson and Halko said all appropriate local, state and federal agencies had been notified and regular meetings were being held to discuss the mitigation of the release.

Halko said the release was in a storm drain and Anderson said the city and Calumet had determined the pipes were intact.

Halko said they’re still investigating the cause of the release.

Halko said that because the release was so small and they were able to address it quickly, the company decided it didn’t merit a press release. She said that had it been a more significant event, they would have issued a media release.

Officials with DEQ said the department will issue a violation letter to Calumet, but because of the minimal amount of volume, doesn’t plan to pursue enforcement. The DEQ hazardous waste section is working with Calumet on any residual clean-up and one of their specialists met with Calumet officials on Thursday.