The Ring of Gullion team will check two rivers in County Armagh at Creggan and Forkhill.
They will be looking for eight specific river flies that are an indicator of the health of the water.
Their larvae live in the gravel and silt of the riverbed and are sensitive to pollution.
If they are not present, it indicates there is a problem.
Organisers have said the main problem in the area's watercourses are nutrients linked to farming.
The volunteers will receive training and will check the rivers once a month, reporting back the data.
The training is being provided by the Ballinderry Rivers Trust, the Riverfly Partnership and the Northern Ireland Environment Agency.
The Riverfly Partnership is a UK-wide scheme to monitor river quality, involving 100 organisations.
They include anglers, conservationists, entomologists, scientists and river managers.
The training is free.
A conservation group is looking for volunteers to monitor river flies as a barometer of the water quality in its area.