Ice and cold temperatures are slowing down the dispersion of a chemical spill near Sarnia, Ont. The equivalent of 1,000 barrels of solvent spilled into the St. Clair River early Sunday morning.

It's unclear how the chemical, which is used in the production of lubricating oil, entered the river.

The toxins are now flowing with the ice-filled river south toward Michigan.

Imperial Oil says the solvent's toxicity in water is very low and it's expected to disperse without causing much damage to the environment.

But water intakes have been shut in six communities as a precaution and Imperial Oil says cold temperatures are slowing down the dispersion of the chemical, which is expected to degrade and evaporate.

"We have been working with the Canadian Coast Guard to work around the ice conditions. I would say overall they are slowing down the dissipation of the material but it's not significant enough to be of concern," said company spokesman Gordon Wong.

Oil refinery in Sarnia

The Ontario Ministry of the Environment has been testing the water and has found levels of solvent far below what is considered dangerous. But the ministry says it will be investigating the circumstances surrounding the spill and testing fish to ensure there are no long-term effects.

This is the latest in a string of incidents in which toxic substances have leaked into the air and drinking water of the people who live in the area dubbed "chemical valley." Sarnia Mayor Mike Bradley says it's time for the government to get tougher on industrial polluters. "No one in this day and age should be in an environment where you can't even trust the water you are drinking," he said.

Ontario Environment Minister Leona Dombrowsky promised to get tougher on polluters. She says the government will increase fines, beef up enforcement and punish companies that fail to report accidents.