ALGONQUIN, Ill. — Sandbags have been provided by local government to Illinois counties that have been affected by recent floods.

Sandbags are cheap to make thanks to economies of scale, the low cost of materials and the help of thousands of volunteers in Lake County, the (Arlington Heights) Daily Herald reported.

However, the Illinois Environmental Protection Agency warns that once the sandbags have come into contact with floodwater, they can’t be reused.

Floodwater can be contaminated with human and animal waste, oil and gasoline residue, and farm chemicals such as fertilizers, pesticides and herbicides. The IEPA said sandbags with visible signs of contamination should be disposed as waste at a landfill.

Sandbags are typically made of polypropylene plastic, while others are made of canvas. IEPA Spokeswoman Kim Biggs says the sandbags made with canvas can be burned with an open burn permit from the agency.

Local governments, such as Lake County, are allowing residents to return them by dropping them off at their public works facilities.

“The sand can be reused; public works can use it for backfill excavation. But the bags degrade over time, so we throw those out,” West Dundee Public Works Director Eric Babcock said. “They can be stockpiled for future use if you keep them dry and out of the sun, tarped and off the ground.”