A research project looking into declining dipper bird populations could provide a valuable insight into the health of the River Frome.
Locals have been invited to help with the Stroud Valleys Dipper Project by monitoring the species, which is highly sensitive to changes in water acidity and pollution.
The University of Gloucestershire said the nature of the birds made them an important bio-monitoring species for freshwater habitats.
Senior lecturer in practical ecology at the university, Dr Mark O'Connell, said he wanted to find out if developments along the River Frome were going to "damage biodiversity".
"The River Frome and its tributaries are more than 56 miles (90km) in length and there is a lot of development in the catchment," he said.
"We need to know if that change is going to damage biodiversity."
