Wisbech Canal Tests
Tests are being carried out to determine if land around the old Wisbech canal is contaminated.
The survey covers a five mile stretch of land between Wisbech and Outwell.
In the 1960s, when the canal was no longer used, it was filled with landfill waste.
Tipping ended in the 1970s, but a survey is now being carried out to identify whether any items placed in the land at that time could be harmful if they escape into gardens, houses or water supplies.
People who live near the old canal are being advised not to let their children play in nearby soil, and gardeners are being warned to wear gloves when working on their land.
Full details about the survey have been sent to households within 250 metres of the canal.
Soil samples will be taken as part of the investigation, and ground gases in and around the former landfill area will be monitored.
Councillor Peter Murphy, Fenland District Council's portfolio holder responsible for the environment, said: "We have a responsibility to carry out this investigation because of the history of this area.
We need to gather more information to find out for certain whether there are any problems and, if so, to decide how to resolve them."
Any Fenland residents wanting more information are asked to contact the district council on 01354 654 321.