DETROIT -- The Washtenaw County Sheriff's Department is looking for information on who stole 250 tons of road salt last week.

The rock/salt mixture was stolen from one of three of Washtenaw County Road Commission's salt storage facilities located on 6 Mile Road and Pontiac Trail.

"This is the stuff that gets us through the winter -- rock salt. You could understand maybe a few handfuls or shovels full but a whole barn? That's what they've taken," said Washtenaw County Road Commission Jim Harmon.

Investigators discovered that the salt was missing Monday morning. Police said thieves were able to break into the facility unit by going through a locked fence sometime between July 1 and Monday morning.

Washtenaw County Sgt. Lisa King said the thieves must have needed at least a dozen dump trucks or loads to haul away the salt.

"Somebody had to have seen this," said King. "Obviously it was tandem trucks brought in and the salt was loaded and taken away. It could have looked like a regular business day."

The mixture is used to de-ice the roads in the winter. City officials said it was left over from the previous year's supply and was supposed to be used in the upcoming winter.

Harmon said the theft was a minor set back and it will not impair the county's ability to service the roads this winter.

The 500,000 pounds of salt is valued at $10,000.

A salt shortage last winter forced many communities to use their salt supply sparingly.

Anyone with information on the salt theft is asked to call the Washtenaw County sheriff's tip line at 734-973-7711.