2002 IRISH SCIENTIST YEAR BOOK

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ENVIRONMENTAL PROTECTION AGENCY
AVRIL BOLAND & MARTIN MCGARRIGLE
Drinking water in Ireland

Overall summary of compliance with the drinking water standards 1991�2000.

In the year 2000, the Local Authorities took and analysed 22,801 samples, which involved 141,955 individual tests of drinking water. The Environmental Protection Agency (EPA) estimate that Local Authorities produced and distributed 92.8 per cent of the sampled drinking water, with 6.8 per cent distributed by group water schemes and a further 0.3 per cent distributed by private sources. The overall percentage compliance with the drinking water standards was found to be 94 per cent.

 Of those tests that exceeded the standards (5.7% of samples), the parameters for coliforms, colour, iron and manganese are the most frequently exceeded. Exceedances of the coliform standard (38.7%) were by far the most frequently found parameters in excess of the standards. A comparison of all exceedances in 2000 as compared to 1999 indicates that the change in compliance rate has improved for heavy metals (0.44%), nitrate (0.23%), odour (1.16%), pH (0.02%), taste (1.21%) and turbidity (1.54%): however, the compliance rate has decreased during the same period for aluminium (0.79%), ammonium (0.78%), coliforms (2.94%), colour (0.18%), iron (0.36%), manganese (0.13%) and fluoride (0.41%).

 An examination of the coliform data reveals that there were 1,712 total coliform exceedances in group water schemes as compared to 1,333 in public water supplies. Not all coliforms are of faecal origin and analysis indicates that there were 510 samples containing faecal coliforms in public water supplies and 1,206 samples containing faecal coliforms in group water schemes.

 In general, the quality of drinking water produced by sanitary authorities remains high (96.7% compliance) and is far superior in comparison to group water supplies (70.8% compliance).

 New technologies are being introduced to treat group water supplies, with this effort being underpinned by the allocation of �533 million under the National Development Plan 2002�2006.

 The EPA undertook a series of audits in 2001 to determine the extent to which results in breach of the standards are being investigated and remedied by the sanitary authorities. The EPA is not satisfied that the informal procedures in place are adequate for dealing with all exceedances of the standards and recommends that Local Authorities prepare documented procedures.
Contact: Avril Boland, EPA HQ,
PO Box 3000, Johnstown Castle Estate, Co. Wexford;
Tel: 053-60600.


Water Quality in Ireland 1998�2000


Trends in Irish River Water Quality 1987�2000: 13,200 km baseline. Class A unpolluted; Class B Slightly Polluted; Class C Moderately Polluted; and Class D Seriously Polluted.

The Environmental Protection Agency (EPA) recently published a national overview of water quality Water Quality in Ireland 1998�2000. For the first time since national monitoring began in 1971, an overall improvement in water quality was noted. Almost 400 km of river channel which had been polluted in the 1995�1997 period could now be classified as satisfactory. Of the 13,200 km of river channel surveyed (based on over 3000 sample sites), 70% was assessed as unpolluted compared with 67% in 1995�1997. Slight pollution was noted in 17% of river channels surveyed, some 12% was moderately polluted, and just below 1% was seriously polluted. The length of seriously polluted channel has also decreased from 122km (1% of channel surveyed) in 1995�1997 to 112.5 km (0.85%) in the period covered by the report. Most of the improvements noted occurred in catchments where intensive catchment management programmes are in place.

 Some 85.5% of the 304 lakes surveyed were classified as oligotrophic or mesotrophic, and thus satisfactory in terms of water quality, compared with 81% of the 120 lakes surveyed in the earlier period. Some 44 lakes were classified as eutrophic or hypertrophic due primarily to diffuse agricultural sources, but some also due to point source municipal and industrial discharges. A reduction in chlorophyll levels in the major Shannon lakes, Loughs Derg and Ree, is believed to be due in part to the introduction of zebra mussels, and partly to a major programme of phosphorus removal at 17 wastewater treatment works. The estuarine and coastal waters survey covered 25 different bays and estuaries. Thirteen were classified as eutrophic, another four potentially so and most of these have been designated as Sensitive Areas under the Urban Wastewater Regulations. Estuaries are generally in good condition but some quite serious problems still exist, with several suffering from organic pollution due to local waste discharges.

 The quality of the aquifers sampled in the period indicated some obvious problems, with indications of organic contamination at a relatively high proportion of the sites examined. Some 14% of sites had elevated ammonia concentrations indicating organic contamination, and faecal coliform levels indicating gross contamination were recorded at 36 percent of the 134 sites examined for this latter parameter. High nitrate values were recorded at 19% of the 216 monitoring sites at which nitrate was measured.

 The results again point to phosphorus as the main driving force behind the water quality problems experienced. A range of phosphorus sources is identified, including municipal sewage treatment works and farm losses.
Contact: Martin McGarrigle, EPA Regional Inspectorate,
John Moore Road, Castlebar, Co. Mayo; Tel: 094-21588.