People are being asked to be vigilant following the dumping of hundreds of tyres at sites across Lincolnshire.
The Environment Agency wants people to report any suspcious dumping of waste tyres as part of its Get A Grip campaign.
Environment management team leader Manfai Tang said: “The tyres have been dumped in lay-bys and watercourses, which can cause a significant flood risk.”
“Suspicious behaviour to watch for includes lorries tipping tyres on the roadside or lay-bys or loaded lorries travelling down isolated lanes and returning empty.”
Anyone with information should contact the Environment Agency on its 24-hour incident line 0800 80 70 60.