The oily substance that spilled into the Grand River last week is in fact oil, officials say.

According to the City of Kitchener, the provincial Spills Action Centre received a call Tuesday from a company reporting that used oil had spilled from a storage tank on its property.

That company has not been identified publicly, other than that it operates out of the area where the spill occurred – around Centennial Road in Kitchener’s east end.

City officials say the company’s direct connection to the public sewer system has been shut down.

Work continues to investigate the full impact of the spill, contain it within one section of the river and ultimately remove the oil from the watershed.