Beavers can help clean polluted rivers and reduce soil loss from farmland, according to a study by Exeter University and the Devon Wildlife Trust.
They looked at a captive colony of beavers in Devon, analysing water before and after it passed through their dams.
They discovered that the dams act as a filter, trapping soil which has run off from farmers' fields, and which contains nitrates and phosphorus from fertilisers..
These chemicals are not allowed into the drinking water supply.
Body found in Bideford fire investigation
Three teenagers currently on bail
Royal Clarence Hotel redevelopment to start
Work to start on historic city centre building
Road closures for Tar Barrels event
Organisers list road closures and residents-only access.
More redundancies at Devon shipbuilder
Redundancies could include managerial roles.
Devon's fire service change alarm response
Changes could save hundreds of thousands of pounds.
Exeter woman averts disaster at Greek airport
Exeter woman hailed 'a hero'.
