The province's environment ministry was alerted after firefighters responded to reports of a petroleum spill Sunday evening in the Rideau River.
Ottawa Fire Services received a call at approximately 7 p.m. from a passerby who reported what they believed to be petroleum under the Adàwe Crossing connecting Overbrook and Sandy Hill.
Firefighters went to the area to investigate and saw some material in the water.
Crews were unable to determine what the floating material was or the source of the potential spill, the fire department said, but reported it to the Ministry of the Environment.
The ministry said Tuesday the city and firefighters closed the investigation Monday morning because they couldn't find any petroleum. A spokesperson said the ministry will continue to monitor the situation.