Dozens of landholders are being contacted following the spread of toxic chemicals from firefighting foam from Melbourne Airport.
Letters are being sent to about 90 landholders following an investigation into contamination of soil, and surface and groundwater within airport boundaries.
"This commissioned research found PFAS (per- and poly-fluoroalkyl substances) is present across the airport in varying levels. In a few locations associated with the historical use of AFFF, concentrations of PFAS in soil were found to exceed current Australian Government Guidelines," an airport spokesman said in a statement on Thursday.
"We're currently in the process of getting in touch with individual landholders to talk to them about our research findings, and how they're using water on their properties."
After conducting detailed risk assessments, the airport says there is a low likelihood of adverse health affects on downstream landowners.
This is because "local water courses are not connected to Melbourne's drinking water catchment".