Introduction
Sewage and diffuse agricultural sources continue to be the main threat to the quality of Ireland’s waters. Measures to improve water quality are being implemented in order to achieve the targets of the Water Framework Directive (WFD).
Ireland has an abundant supply of water that is used for drinking water, provides an important habitat for plants and animals, and is an amenity for recreational activities. Although freshwater is abundant, it is not limitless in quantity, it is not evenly distributed across the country, nor is it of good quality status everywhere. Nutrient enrichment causing eutrophication is the main threat to Ireland’s aquatic systems.
The water quality in most estuarine and coastal waters, and bathing waters remains high. Microbiological contamination of some bathing waters and drinking waters may pose a risk to public health in certain areas. In terms of water resources there is an increasing demand for drinking water, particularly in the greater Dublin area.
State and Impacts
Groundwater
In the period 2007-2009, there was a general reduction in phosphate and nitrate concentrations compared with the previous period which has been attributed to increased rainfall, reductions in inorganic fertilizer usage, improvements in organic fertilizer storage and the implementation of land-spreading restrictions.
Elevated nitrate concentration in groundwater remains an issue, particularly in the southeast and south of the country. It may contribute to eutrophication of surface waters and affect drinking waters. Diffuse agricultural pollution is considered the most significant source.
Elevated groundwater phosphate concentrations, particularly in karst limestone areas, may be contributing to eutrophication in rivers and lakes.
Rivers
Fifty-two per cent of river water bodies are classified as having good or better ecological status, i.e. satisfactory, based on the WFD Ecological Classification for river water quality for the period 2007-2009. 28 per cent of river water bodies are classified as having moderate, 19 per cent poor and 1 per cent bad ecological status.
High Ecological Quality River Sites
High ecological quality at river sites is an indicator of largely undisturbed conditions and reflects the natural background status or only minor distortion by anthropogenic influences. Such sites are used as reference sites from which deviation in quality is measured. These sites play an important part in conserving individual species and overall catchment biodiversity and must be protected under the WFD.
The percentage number of high quality sites has almost halved in the last 21 years from almost 30 per cent of the total sampled in the 1987-1990 period to less than 17 per cent in 2007-2009. The seven-fold decrease in sites attaining Reference Condition (Q5) is particularly striking. These sites now comprise less than two per cent of the total surveyed.
Lakes
In the period 2007-2009, 222 lakes were examined representing 988.5km2 of lake surface water or approximately 65 per cent of the surface area covered by lakes in the country.
When assessed for ecological status, according to the requirements of the Water Framework Directive (WFD), 105 (47.3 per cent) lakes were of high or good status with the majority (38.3 per cent) , in the latter category. 92 (41.4 per cent) lakes were of moderate status, 19 of poor status and 6 of bad status.
Lakes in the high and good status categories accounted for 335 km2 (35 per cent) of the lake area examined. A further 502 km2 (51 per cent) were assigned moderate status. Poor status lakes accounted for 127 km2 (13 per cent) of lake area examined. In all, 643 km2 (65 per cent) of the lake area examined was in the moderate or worse ecological status classes.
Transitional and Coastal Waters
A total of 121 transitional and coastal water bodies were assessed for the period 2007-2009 for WFD status classification. Of these, 55 (46 per cent) were classified as either high or good status with the remaining classed as moderate or worse status.
In relation to trophic status, 89 water bodies were assessed, with 44 (49.5 per cent) classed as unpolluted, 31 (34.8 per cent) intermediate, 5 (5.6 per cent) potentially eutrophic and 9 (10.1 per cent) eutrophic. This represents an improvement compared with the most recent previous period, with 4 fewer water bodies being classed as eutrophic.
Bathing Water
Over the past ten years the quality of water at designated bathing areas in Ireland has remained high. The percentage of bathing waters that are of sufficient water quality has remained relatively stable at between 92 and 99 per cent while the percentage of bathing waters of good water quality has fluctuated between 77 and 92 per cent. At sites that are failing to meet the EU mandatory values there are various contributing factors including inadequate sewage treatment, discharges from combined storm overflows and pump station failures. Higher than usual rainfall in recent summers may have exacerbated these problems in some cases.
Drinking Water
The most important indicators of drinking water quality in Ireland are the microbiological parameters and, in particular, Escherichia coli. The presence of E. coli in drinking water is a good indication that either the source of the water has become contaminated by faecal pollution or the treatment process at the water treatment plant is not operating adequately.
In 2010 public water supplies had a 99.8 per cent compliance rate and over the past 10 years the number of supplies contaminated with E. coli has reduced year on year. In general, the microbiological quality of private group water schemes remains inferior to public supplies with a compliance rate in 2010 of approximately 96 per cent. However, there have been significant improvements in recent years in the quality of water in private group water schemes.
Drivers & Pressures
The two main sources of pressure on water quality are from agricultural activities and municipal wastewaters. These activities can contribute to nutrient enrichment, organic pollution and siltation of water bodies.
Agricultural activities associated with pollution include land spreading of artificial fertilisers and animal manures in unsuitable climatic and ground conditions, silage effluent discharges, farmyard runoff, and watering animals.
Municipal pollution sources include sewage, waterworks effluent, on-site wastewater treatment systems and diffuse urban inputs. Sewage discharges comprise the main municipal pollution source. Pollution from municipal wastewater treatment plants arises where there is inadequate treatment, combined storm overflows and direct untreated discharges. In most rural areas the majority of the population uses individual septic tanks that, if poorly sited and/or not properly maintained, can pollute groundwater, surface water and drinking water supplies.
Other activities which may impact on water bodies include forestry, industrial activities, quarrying, dredging, fish farming, bog development, civil works and housing development.
Responses
Significant investment has gone into improving the water services infrastructure (for drinking water and urban wastewater), with over €4.6 billion invested over the last decade.
This has resulted in a dramatic improvement in the level of treatment provided for urban wastewater. 93 per cent of urban wastewaters now receive at least secondary treatment compared to less than 30 per cent in 2001. However, almost half of secondary treatment plants are failing to meet EU and national effluent quality and/or monitoring standards. In addition, some large urban areas still do not have the mandatory level of treatment required by the Urban Waste Water Treatment Directive. A system for EPA licensing or certification of wastewater discharges from areas served by local authority sewer networks was brought into effect in September 2007. The purpose of this authorisation system is to prevent and reduce the pollution of waters by waste water discharges. Waste water discharge licenses may set more stringent requirements for effluent quality than the Directive, depending on the local situation and the receiving waters.
This investment has also resulted in increased treatment capacity for drinking water by a level equivalent to the needs of a population of 855,000 and storage capacity has increased by a level equivalent to the needs of a population of 1,510,000.
In 2009 the EPA revised its code of practice establishing a framework of best practice in relation to the development of wastewater treatment and disposal systems in unsewered rural areas.
The implementation and enforcement of the Nitrates Action Plan under the EU Nitrates Directive is the most important measure to address diffuse agricultural pollution of freshwaters.
In line with elsewhere in Europe a series of river basin management plans has been developed under the Water Framework Directive. The challenge for water resources management in Ireland will be the successful development and rollout of effective programmes of measures.
Special attention has been given to the protection of high status water bodies with a guidance document being drawn up for local authorities under the EPA STRIVE environmental research programme.
Outlook
Many water bodies will require remedial measures to meet the objectives of the Water Framework Directive (WFD). Protection and restoration of high quality waters will also be a significant challenge. Eight water management issues have been identified as being of national importance:
- Wastewater and industrial discharges
- Landfills, quarries, mines and contaminated lands
- Agriculture
- Waste from unsewered properties
- Forestry
- Usage and discharge of dangerous substances
- Physical modifications to surface waters
- Abstractions
Programmes of measures under River Basin Management Plans aim to address these issues as they arise within individual river basin districts.
The priorities for Government water services investment over the coming years include measures: to improve drinking water conservation (e.g., leakage control); to meet drinking water and wastewater treatment standards and ensure compliance with the WFD; and to meet forecasted increases in demand.
More generally water resources are likely to be impacted by the projected changes in climate over the coming decades. These impacts are expected to include summer water shortages in the east, the need for crop irrigation, potential deterioration in water quality, and an increased likelihood of flooding and coastal erosion.
