Northern Ireland Water has been fined £1,000 for a pollution incident in Co Londonderry.
A mechanical failure meant equipment controlling the flow from treatment works at Greysteel did not work properly. This caused a discharge to a river.
A clean-up was not required and no fish were killed during the November 2008 incident.
NIW pleaded guilty at Limavady Magistrates' Court.
A spokesman for NIW said: "NI Water acted to stop the discharge to the river as soon as staff were made aware of it.
"NI Water identified areas within the works that will improve the alarm process and reduce future discharges, which will minimise the risk of this occurring again."