The leading American hard-disk manufacturer pleaded guilty at Limavady Magistrates' Court on Wednesday to a charge of knowingly or otherwise discharging poisonous, noxious or polluting matter into a waterway in Limavady in contravention of the Water (NI) Order 1999, relating to events occurring on July 22, 2005.
Three weeks ago the company entered a guilty plea to a related charge of discharging trade effluent into the local sewerage system in 2005 without providing the Department of Regional Development with sufficient notice.
During sentencing on Wednesday the company was fined a total of £6000 for these offences.
A PPS spokeswoman explained how a fish kill on the Roe on Friday, July 22, 2005, prompted an investigation by the Department of Environment, during which a number of samples were taken from a stretch of river approximately three kilometres in length near the Seagate plant.
Upon speaking to Seagate staff it emerged the company had made a change to chemicals used in a metal plating process in the plant, the court heard.
Investigations later revealed that one of the chemicals introduced to the process was "highly toxic to aquatic life" and had been implicated in fish kills elsewhere in the past.
A sample taken from surge treatment works in close proximity to the Seagate plant following the fish kill, revealed a "high concentration of the chemical" whilst the tide had had the effect of dispersing this along the three kilometre stretch of river concerned, the court was told.
A defence solicitor said Seagate had no previous convictions and an otherwise "very good record on the environment."
She described the case in hand as "very much a one off incident" and said the company had informed representatives from the Department of Regional Development of a change in its chemical processes on June 22, 2005, but had failed to provide written notice.
She claimed there was no evidence to show whether the fish were killed by a lack of oxygen or the Seagate chemical discharge.
Resident Magistrate, Eamon King, said he regarded the incident as a very "serious matter" saying: "Industrial processes have an obligation to examine that anything emanating from the plant is not harmful to local wildlife."
He suggested greater diligence in researching the background and history of the chemical involved in the fish kill could have prevented this from happening.
He fined the company a total of £6000 imposing £182 court costs, but said he was surprised there was no petition for analysis and restocking costs.
As a result of a release of pollutants into the River Roe on Friday, July 22, 2005, 140 dead salmon and 95 sea trout were recovered from the toxic water in a joint operation on 24 and 25 July, according representations by the Roe Valley Angling Association to Limavady Borough Council at the time.