Despite the department spending an estimated £8 million on trying to remove nitrates from the water released into the sea since the late 1990s, levels still exceed the legal limit.
Environmental protection officers have now submitted a file of evidence about breaches of the plant’s discharge permit to the Attorney General, who is considering whether to bring the matter to court.
Their concern centres on the fertilising action of the nitrates, which causes the growth of plants like sea lettuce that can create a nuisance and harm other marine life.
