Water Quality in Ireland 2005 - Key Indicators of the Aquatic Environment

Date released: Aug 17 2006

Ireland's water quality continues to be of a high standard, according to the Environmental Protection Agency summary indicator report entitled Water Quality in Ireland 2005, published today. The report, the first of a new series of summary statistics, is based on monitoring results for surface and groundwaters for the period 2003 - 2005.

This report sets out in a concise way ten core indicators of water quality, based on the most up-to-date data available, said Dr. Jim Bowman, Programme Manager, EPA. While these data are encouraging there remains an unacceptable level of polluted waterbodies in the country.  30 per cent of rivers, 10 per cent of lakes and 22 per cent of estuaries and coastal waters are in a condition that will require remedial measures if we are to protect our valuable water resources and comply with the requirements of the Water Framework Directive. The indicators chosen reflect water quality conditions and the report shows that, for example, the number of fish kills in our rivers, and the level of bacterial contamination in our groundwaters remain at unacceptable levels.

This report deals with 13,200km of river and stream channel, 421 lakes, 67 tidal water bodies located at estuarine and coastal areas and 307 groundwater sources.

Report Findings

Surface Waters

Rivers

The proportion of river and stream channel length with an overall satisfactory water quality status has increased by one per cent in the latest period (70.2%) compared to the previous period of assessment (69.2%). There was a reduction (-1.2%) in the moderately polluted length but a small increase in the proportion of slightly polluted channel (+0.2%).  In contrast the overall proportion of seriously polluted channel has remained unchanged between the two periods.
Nitrate levels in 11 large rivers showed differences across the country with notably higher levels in the southeast and south. Nine of these rivers have considerably increased nitrate levels in 2005 as compared with when first sampled in the late 1970s or early 1980s.
The increase in nitrate values has coincided with the demise of the pollution-sensitive pearl mussel in some rivers.

Lakes

While almost 90 per cent of the 1,050 km2 of lake surface area examined in 2003-2005 was in a satisfactory condition, this represents a slight deterioration compared to the 2001-2003 period.

Of the 421 lakes assessed, water quality in 68 of these was less than satisfactory, with 13 lakes classified as being highly polluted.

Fish Kills

There were 45 fish kills recorded in 2005, which were attributed largely to activities associated with agriculture, industry and local authority services. The number of instances of these events remains at an unacceptably high level.

Estuarine and Coastal Waters

The overall quality in the 67 water bodies from estuarine and coastal areas examined in 2001-2005 showed improvement, with a decline from twelve to ten in the number of water bodies being classified as eutrophic (over enriched).

Data from the Marine Institute's winter nutrient monitoring programme, in coastal waters of the western Irish Sea and southern Celtic Sea, indicate no instances of excessive nutrient enrichment in these waters.

The quality of shellfish waters improved in 2005 with a notable increase in those waters assessed to be of the highest quality for the purpose of shellfish production and the elimination of those of the lowest quality.

A reduction was recorded in the number of reported pollution at sea incidents from 59 in 2004 to 46 in 2005. These events were attributed approximately to oil spillages (72 per cent) and other substances (28 per cent), e.g. algae or unidentified blooms. Diesel and gas oils were the most frequently identified polluting substances.

Bathing water

The overall quality at the 131 bathing waters in Ireland remains very good although the number of sites complying with EU mandatory values in 2005 showed a reduction of two per cent when compared with 2004. 82 per cent of sites complied with the National Limit Values.

Groundwaters

Bacterial contamination

In Ireland, groundwater is a significant source of drinking water supply. The presence of faecal coliforms in groundwater is taken as evidence of faecal contamination and provides an indication that pathogens (disease-causing organisms) may be present.

Since 1995 there has been a general increase in the percentage of samples showing zero contamination and a decrease in the percentage of samples showing gross contamination. Approximately 30 per cent of the 1714 samples of groundwater taken between 2003-2005 showed bacteriological (faecal coliform) contamination, with some 11 per cent of samples being grossly contaminated. The groundwater monitoring locations in karst limestone areas appear to show the greatest degree of contamination, because pollutants can move more freely through fissures in the underlying rocks.

Nitrates

Between 2003 and 2005 approximately 23 per cent of the groundwater locations examined exceeded the national guideline value for nitrate concentration for drinking water with two per cent breaching the mandatory limit.

Elevated nitrate concentrations were recorded in monitoring points close to potential point source waste discharges. However, the spatial distribution of monitoring locations with elevated nitrate concentrations appear to relate to areas with more intensive agricultural practices, which suggests that diffuse, agricultural sources are the cause.

The report is available on the EPA web site at www.epa.ie/downloads/pubs/water/indicators  or from the EPA's Publications Office, McCumiskey House, Richview, Dublin 14 on 01-2680100.