Co Tipperary is being considered as the possible source of pollution affecting a river in Co Limerick.
Trout and salmon are reported to have died on the stretch of the Drumcamogue River near Knocklong.
The authorities are saying that while there is no danger to the public water supply, they believe an extensive number of trout and salmon have been killed and that the problem stems from an agricultural source in Co Tipperary.
The situation is being monitored by Limerick City and County Council along with the Inland Fisheries Board.
