Irish Water has pleaded guilty to raw sewage pollution of a bathing and swimming area at Blacksod Bay in Co Mayo and contaminating a Co Roscommon river.
It pleaded guilty at Dublin District Court today to breaching the terms of its licence.
Judge Anthony Halpin accepted each instance was at the lower end of the scale, and that Irish Water had addressed the problems.
He imposed fines totalling €900 on Irish Water which agreed to pay the Environmental Protection Agency's costs in bringing the prosecution.
EPA inspector Una O’Callaghan said a water treatment facility, one and a half kilometres from Roscommon town, discharged treated water into the River Hind.
It had been given until 2020 to reduce emission limit values from orthophosphate from 0.8 mg per litre to 0.2 mg per litre.
The orthophosphate caused vegetable growth which could affect aquatic life.
In April 2020 the emission limit values were 0.69 mg per litre and 0.37mgs litre when tested in September.
She agreed with prosecution solicitor Zoe Richardson that Irish Water has now brought the emission limit values from orthophosphate down to the appropriate level.
The court heard that an overflow of the Belmullet water pumping plant resulted in a discharge of 30,000 cubic metres of raw sewage into a bathing section of Blacksod Bay.
The untreated water caused slight discolouration.
Defence counsel Eoghan Cole asked the court to note the co-operation of his client with the EPA and to treat the offences as being at the lower end of the scale.
He also pointed out the breach of regulations in Roscommon did not result in any fish kill. Irish Water had taken over the Co Mayo operation from the county council.
Counsel said that in both cases Irish Water has taken steps to address the problem which was accepted by the EPA.
The court heard that Irish Water had 16 prior convictions for breaching wastewater discharge licences at other treatment plants.
It could have faced fines totalling €40,000 but five counts were withdrawn and it pleaded guilty to three charges, based on a hearing of full facts.
Judge Halpin, however, noted the improvements had been carried out at the facilities.