It's claimed that low water levels could be a contributing factor to deaths of up to 1000 salmon in Ballisodare River.
A multiagency investigation is ongoing along the river this lunchtime with a number of representatives out monitoring the water and carrying out further tests.
Meanwhile, the nearby Owenmore River in Sligo and its tributaries have been also closed for all fishing due to the ongoing outbreak of disease in the salmon population.
The State has closed the system until further notice.
Speaking from Ballisodare this afternoon, Local Sinn Fein Cllr Thomas Healy says the community is anxious to get answers: