According to the Windsor Port Authority, salt shipments more than quadrupled in January over the same month last year.

The increase is due mostly to an increased use of salt on roads.

Windsor Salt shipped roughly 20,000 tonnes of salt out of the port of Windsor in January 2013.

This January, the company shipped more than 100,000 tonnes of salt.

According to David Cree, president and CEO of the Windsor Port Authority, stock piles of salt on the banks of the Detroit River are low, but he said officials figure they can bring that up by spring.

"It's been a very good winter so far for the salt company but not a very good winter for the communities that need their product," said Cree.

Salt is being shipped by tug and barge over to Detroit. Some is also going into the upper Great Lakes by freighter.

Calls to Windsor Salt were not immediately returned.

The Windsor salt mine distributes de-icing and industrial salts throughout the Great Lakes region.

Unifor Local 1959 says all three shifts are working five days a week and new hires were made late in 2013.

The union and Windsor Salt are in contract negotiations. The current contract expires Feb. 15.