COEUR d'ALENE - The smell of fuel and a tell-tale rainbow slick on the water's surface sparked cleanup operations Friday along the Spokane River near the Riverstone complex.

Coeur d'Alene Fire Department responders worked with members of the Region 1 Hazardous Materials Team to contain an oil spill discharged into the river from a storm drain just north of the U.S. 95 bridge.

"This illustrates why we have a stormwater spill prevention and education program," said Coeur d'Alene deputy city administrator Jon Ingalls. "We've tried to get the word out. Don't dump materials into the catch basins because they're going to end up in the lake or the river."

The amount of oil discharged is unknown, but Ingalls said it was likely a small quantity.

The liquid hydrocarbon stayed close to the shoreline as it spread across the river's surface. Its source and the exact composition of the liquid was not immediately known.

Responders floated oil absorbent booms and pads near the docks of the Bellrive waterfront condos.

By 4 p.m., it was estimated the spill was 95 percent contained.

The booms, designed to contain and soak up petroleum spills from the water's surface, will remain in place, officials said.

Ingalls said workers will be taking samples from manholes to try and determine the spill's point of origin.

"It could have been used motor oil that somebody dumped down a storm drain," Ingalls said.