A third of Ireland's rivers and lakes are polluted, with farmers the main culprits, a new report on water quality said today.
Although there has been a slight improvement in the water quality, the pollution of rivers and lakes from agricultural sources remains the greatest challenge, according to the National Phosphorous report from the Environmental Protection Agency.
It said that only 11 of the 34 local authorities had carried out significant farm surveys to check on slurry storage, silage effluent containment and other pollution control measures.
"The current level of work in this area will have to rise dramatically in order to make a significant impact on this type of pollution."
The presence of excess phosphorous in rivers and lakes can stimulate excessive plant growth and kill off fish life, a process known as eutrophication.
The report found the water quality at 63.4 per cent of river and lake monitoring stations was compliant with the Phosphorus Regulations, which was an increase of 3.4 per cent on 1990s levels.
Eutrophication is seen as the main reason for the decline in the length of unpolluted river channel from 77 per cent in 1987-90 to 69 per cent in 2001-2003, when the most recent study was carried out.
The report said there was a high percentage of farmers who understood the implications for the environment of poor practices, and had demonstrated a responsible approach.
"However, in such a large sector, there is inevitably a small number that have not yet adopted the required policies and practices."
When local authorities carried out detailed farm surveys on area with polluted water supplies, they received a high degree of co-operation from farmers.
The report said Ireland was currently on target to achieve compliance with the EU Water Framework Directive (WFD), which requires that good water quality in rivers and lakes be achieved by 2015.
The Environmental Protection Agency's enforcement office said the decline in the number of river stations recording the highest biological water quality was a worrying trend.
There were significant improvements in water quality in Dublin City, Kildare, Fingal, Westmeath, South Dublin and Meath. But water quality dropped significantly in Donegal and Wicklow.