Loughs Agency says it investigated two incidents at a wind farm construction site last week.
It says there was a breach in a berm used to hold back stripped peat, followed by a separate discharge of dirty water into a watercourse leading to the Elatagh River.
The wind farm company contained the discharge, while Fishery Officers collected samples for analysis.
Loughs Agency says it is liaising with the company regarding containment measures at the site and will continue to monitor water quality downstream.
It says inspections have found no water quality issues since the discharge.
