City of Kitchener works to clean up after spill detected in Grand River

Spilled oil is seen along the shore of the Grand River in Kitchener on Saturday, April 30, 2016. (Nadia Matos / CTV Kitchener)

A major cleanup is underway on the shores of the Grand River after a thick black oily substance was dumped into the sewer system, officials say.

Officials believe petroleum was released into the sewer system off of Centennial Road in Kitchener, eventually making its way down the Grand River.

Investigators are trying to track down where the substance came from.

Approximately 250 meters along the north shore of the river is affected.

Environmental crews have been cleaning up the mess since Friday evening.

The Region of Waterloo, the Grand River Conservation Authority and downstream municipalities have all been notified.

Updates will be provided as new information becomes available.