Irish Water has pleaded guilty to breaches of licence conditions at a waste water treatment plant in Tipperary.
The Mullinahone plant was one of six across the country for which the utility was taken to court by the Environmental Protection Agency.
EPA inspector Dr John Feehan said the plant discharged into the Mullinahone stream, causing “poor quality” water.
He said the water from the plant had 30 times the set limit for ammonia and 46 times the limit for ortho-phosphate. It was supposed to have been upgraded by 2015.
All of the treatment plants been due for upgrade but deadlines have been pushed back to 2029.
Judge Anthony Halpin imposed a fine of €1,000 for the Mullinahone breach.