Improvements in the Republic's river water quality seen in the late 1990s have not been sustained - largely due to agricultural pollution - a three-year study published yesterday has found.
The Water Quality in Ireland 2001-2003 report launched by the Environmental Protection Agency (EPA) examined 13,000 kilometres of rivers and streams, 500 lakes, 69 tidal waters and 300 groundwater sources.
Although it concluded that overall water quality in tidal areas and lakes remains high, 30 per cent of rivers surveyed were classed as moderately or slightly polluted.
The report also found a reduction in the number of coastal bathing areas that comply with water quality guidelines, and intermittent contamination of groundwaters with faecal coliform from sewage.
The EPA said the main pollutants are sewage from municipal treatment works and agricultural chemicals such as nitrates and phosphates, which drain through the land into rivers.
Sewage represents the more serious type of pollution but the report notes that incidences of this actually declined over the three years of the study to its lowest level since the early 1990s. This has been attributed to the increase in the number of new waste water treatment plants.
In contrast, the number of kilometres of slightly polluted rivers has increased.
The State has also been prosecuted by the European Commission for its failure to implement the EU nitrates directive. A draft action programme was rejected by Brussels earlier this year and although amendments have been suggested by the Government, a formal strategy has not been submitted.
However, the EPA said the findings regarding lakes were "encouraging". The designated freshwater bathing places on lakes all showed compliance with national regulations. Some 91 per cent of the total lake water examined was deemed to be satisfactory. Exceptions included the north midland lakes such as Sheelin, Oughter, Gowna and Ramor where pollution from intensive pig farming was expected.
Of the 69 tidal areas assessed 78 per cent were classed as unpolluted, showing only slight signs of eutrophication. Monitoring of radioactivity in the marine environment by the Radiological Protection Institute showed only relatively low levels recorded in contrast with higher levels recorded in the 1970s and 1980s.
Speaking at the launch of the report yesterday Minister for the Environment Dick Roche welcomed the "positive aspects" of the report including the main conclusion that the overall condition of Irish waters was satisfactory.
But Mr Roche said aspects of the report were "less comforting". These included the condition of rivers and the finding that there is a need to control nutrients, which lead to eutrophication, from all sources. "We must address every source of pollution, be it agriculture, urban waste water, industry or any other activity," said Mr Roche.
He is committed to ensuring measures were in place to address "all the water quality challenges we now face".
