The Environment Agency is urging companies between Wadsley Bridge and Neepsend in Sheffield to help identify and prevent pollution in the River Don.
Environment Officers are targeting industrial businesses around the River Don in the north west of the city, where pollution incidents have affected the watercourse in the past.
In July, a fire and oil spill at a waste management facility near Kelham Island affected the river and its users, and there have since been other incidents involving pollutants entering the water. The Environment Agency has now written to local businesses in the area and environment officers will be visiting them on Wednesday to carry out inspections to identify potential pollution sources and give further advice on oil storage, handling and infrastructure.
The aim is to preserve and protect wildlife in the river.
Anyone spots any pollution on land or water around the River Don should call 0800 807060.