Researchers from Exeter University say they are close to discovering the source of dangerous bacteria being released into rivers.
It is hoped the research will help identify the source of river bacteria
A team from the university has been surveying the River Exe as part of a project to improve water for shellfish.
Samples have been collected from six locations on the river and tested for e-coli.
The European study, which is costing £650,000, will help the Environment Agency find where problems are arising.
Scientists will be able to identify DNA from the samples.
The aim is to discover whether the bacteria has come from an animal or human source.
The Environment Agency will then be able to work out if river pollution is being caused by sewage works, farmers or individual septic tanks.
The European Union is investing millions of pounds to improve water quality for shellfish.
Lessons learnt from the Exe will also be used to help improve the river quality on the Helford in Cornwall.