Flint, MI — City of Flint officials confirmed today that a spill identified in the Flint River in late June was “a petroleum substance.”

According to a July 20 City of Flint press release, test results from samples taken from the spill site near the Utah Avenue Dam have verified the filmy contamination as petroleum.

In good news, the release adds, “based on the limited amount of material found in the storm sewer system, the City of Flint believes that approximately 10 gallons were released into the river, contrary to the initial estimate of 200-300 gallons.”

The release goes on to note that the samples confirming the spill as a petroleum substance were collected from three locations along the storm sewer pipe near the dam and picked up for testing on July 5.

Those samples were then analyzed for “Oil & Grease,” Total Volatile Toxic Organics (VTOs), Gasoline-Range Organics (GRO), Diesel-Range Organics (DRO) and Oil-Range Organics (ORO).

“Results show trace amounts of Oil & Grease and VTOs. GRO was not detected,” the release reads. “DRO and ORO were found in the samples collected, confirming that it was a petroleum spill.”

Further, after investigating the storm sewer line, “the City of Flint has concluded that the spill originated near Dort Highway, was a one-time discharge, and has stopped.”

Booms, or absorbent barriers, have been in place on the Flint River since June 29, the date the spill was discovered.

The release notes that city officials believe residue at the spill’s outfall “has been completely absorbed” since, but plans to leave the booms in place until Monday, July 24 as a precautionary measure.

At present, the city has not lifted its recommendation to avoid contact with the river near the Utah Avenue Bridge. The release says the city will do so “when the cleanup is determined to be complete.”

City officials did not respond to Flint Beat’s request for who or what entity was responsible for the spill nor if the city plans to take any action against the spill’s originator.

Kate is Flint Beat's associate editor. She joined the team as a corps member of Report for America, a national service program that places journalists into local newsrooms to report on under-covered issues....