The most comprehensive report conducted on Irish rivers, lakes and coastal waters records further evidence of an almost unrelenting decline in freshwater quality, with a third of river channels classified as polluted.
The Environmental Protection Agency report over the three-year period between 1995 and 1997 concludes that the further decline in the quality of rivers, in particular, indicates "the present level of water pollution control is not adequate".
The disappointing message is of "continuing decline of our water with obvious implications for our salmon and trout stocks", which will reflect on the State's green image, said EPA director Mr Padraic Larkin. It indicated more strenuous efforts were needed to tackle pollution.
The picture, dating back to 1971, shows "a distinct trend of continually increasing slight and moderate pollution in rivers but also, especially of late, a reversal of the trend of decreasing serious pollution". This is likely to impair the ability to sustain pollution-sensitive salmon and trout fish in many areas as their water quality steadily deteriorates.
The report, published yesterday, is based on data arising from surveys carried out on over 13,000 km of rivers and streams, 120 lakes and 23 estuaries.
While the EPA concludes that the overall condition of Irish waters remains satisfactory (especially when compared to other European countries), this is primarily due to low population density and "still moderately developed agricultural and industrial sectors". Its concerns have to be put in the context that once a system is polluted it is extremely difficult to rehabilitate it.
In general, lakes are in much better condition because of their larger volume and flushing ability and they do not directly receive municipal sewage, though the EPA conclusions are based on a much lower level of monitoring compared to rivers.
The report finds that bathing waters, both freshwater and coastal, are generally of excellent condition, similarly the quality of water in canals. Data for estuarine and coastal waters indicate that, with a few exceptions, they are not significantly polluted.
Over-enrichment of freshwater is the main problem, caused by eutrophication, so much so that some estuaries may be affected. This damage is primarily caused by phosphate discharges from agriculture and sewage treatment plants which upset the waters' natural balance.
Figures on seriously polluted river locations show "a very substantial increase in the number being seriously polluted by sewage" - an increase of 29 locations. The most likely cause of this is outdated or overloaded sewage treatment facilities.
Of the lakes examined, 19 per cent were less than satisfactory, so much so that fishing or recreational use was likely to be impaired. Five of the most seriously polluted lakes were located in the midlands and includes two of the State's largest lakes, Ramor and Oughter. A marked deterioration in the quality of Lough Leane in Co Kerry is highlighted.
The report outlines concerns about groundwater quality even if current pollution in the form of nitrate contamination is localised. But up to 30 per cent of samples were found to contain coliform bacteria indicating faecal contamination. Special protection of these water sources will be necessary to supply drinking water, particularly where surface water availability is limited, it adds.
In many cases of eutrophication, where discharges upset the natural chemical balance of water, improvements are unlikely to happen, or to be maximised, unless there is a concerted effort to control phosphorus losses arising from farming activity, it notes. This has to involve development of "nutrient management plans" and careful evaluation of manures and slurries being applied to land.
