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).
In summary, the assessment of Ireland’s water resources shows that:
- 71 per cent of river channel is at high or good status
- 44.6 per cent of lake area monitored is at high or good status
- 64 per cent of the area of transitional and coastal waters are at high or good status
- 85.6 per cent of the area of groundwater aquifers is at good status
Water quality in Ireland compares favourably with that in other EU countries. However, similar to many other EU countries, Ireland still faces considerable challenges to meet the objectives of the WFD within the required timeframes. The three main challenges for water quality management are to eliminate serious pollution associated with point sources; to tackle diffuse pollution; and to use the full range of legislative measures in an integrated way to achieve better water quality. A key aspect is that focusing measures on rivers, where monitoring has identified particular causes of pollution, will help reduce pollutant loading to lakes and coastal waters as well as improving river quality.
In addressing these challenges, improvements are also required in the governance and administrative systems for water management in Ireland to ensure that they are optimised to support the delivery of Ireland’s obligations under the WFD and other water legislation.
State and Impacts
Groundwater (GW) is important as a source of drinking water in Ireland – providing approximately 25 per cent of drinking water nationally. It also has significance in driving the ecology of many rivers, lakes and estuaries, especially during low-flow periods when groundwater forms a significant part of surface water flows.
The bulk of poor-status groundwater bodies, particularly in the Western and Shannon RBDs, are in areas where groundwater is contributing significant loads of phosphate to surface water bodies that are failing to meet their WFD objectives because of eutrophication from diffuse sources. A small number of water bodies are also at less than good status due to site-specific contamination, e.g. from historical mining in the Avoca catchment and at Silvermines. Elevated groundwater phosphate concentrations, particularly in karst limestone areas, may be contributing to eutrophication in rivers and lakes.
In the period 2007–2009 there was a general reduction in nitrate concentrations compared with the previous period, which has been attributed to increased rainfall, reductions in inorganic fertiliser usage, improvements in organic fertiliser storage and the implementation of land-spreading restrictions. In comparison with 2009, the slight increases in nitrate concentrations that are observed in 2010 are attributed to reduced rainfall leading to less dilution of the nutrients in the water body.
Over 13,000 km of river channel is assessed by the EPA on an ongoing basis at over 2,500 sample points. The most recent assessments show that approximately 71 per cent of river channel is classed as unpolluted in Ireland – achieving at least good ecological status. However, approximately 29 per cent of monitored river channel length is polluted to some degree. Trends over time show:
- an overall decrease in the length of river channel that is classed as unpolluted, although there have been some improvements in recent years
- a decline in the length of seriously polluted channel
- an increase in the channel length affected by slight to moderate pollution – mainly due to eutrophication (over-enrichment with phosphorus and nitrogen).
Monitoring for WFD purposes commenced in 2007. 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. Some 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-status waters such as rivers with healthy populations of freshwater pearl mussel require very high standards of protection. However, the number of such high-status waters has declined significantly in recent decades. This decline is worrying, and site-specific, targeted interventions are needed in the catchments with high-status sites to prevent further loss.
In the period 2008–2010, ecological status was assigned to 208 lakes by the EPA, representing 981 km2 of lake surface water covering 65 per cent of the total lake surface area in Ireland. Some 97 lakes (46.6 per cent) were of high or good status with the majority, 39 per cent, in the latter category.
As noted also with river quality, there is no room for complacency in terms of lake water quality, with only 46.6 per cent of the monitored lakes achieving the targets of the WFD. A reduction in the total amount of nutrients delivered to lakes via their tributary rivers is a key focus of the WFD programme of measures. The EPA is working towards a set of phosphorus loading limits for individual lakes, based on an extensive new set of bathymetric measurements made over recent years that will allow volume and residence time of water in these lakes to be calculated and, thus, phosphorus loadings in terms of annual targets. Programmes of measures to achieve these new limits will need to be more focused than current measures, and to bring about further improvements in lake water quality. As with the rivers feeding into the lakes, these measures will focus on nutrient sources, both point source and diffuse.
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 over 50 per cent classed as moderate status and 3 per cent assigned poor status.
In European terms, Ireland’s transitional and coastal waters are relatively good – as might be expected from Ireland’s western location on the North Atlantic. This is borne out by the OSPAR Commission assessments (OSPAR, 2009), which found that problem areas are confined to estuaries and the nearshore coastal zone. While transitional waters are under pressure due to the majority of Ireland’s population living at or next to the coast, they still rank in the top five across Europe. For coastal waters, Ireland ranks at or close to the top in terms of proportion of water bodies meeting high status or high and good status. 70 per cent of Irish coastal waters already reach this standard.
Urban wastewater treatment plants pose the biggest threat to transitional waters, but major improvements have been seen where new treatment plants have been installed (e.g. Sligo). Nitrate from agricultural sources is a particular issue in some estuaries such as the Argideen, near Courtmacsherry in Cork, where extensive sea lettuce growths have given rise to odour and nuisance problems. As with rivers and lakes, the reduction of nutrient inputs is the key to improving the status of Ireland’s transitional and coastal waters.
Drivers & Pressures
There is now a very good understanding of causes of water pollution in Ireland, based on longterm pollution-monitoring field work and supported by detailed risk assessments undertaken for the WFD, as well as international research. The pressures that impact on ecological status are clear and the corresponding remedies are also clear.
The EPA has identified the main suspected causes of pollution in water quality reports published over many years.
A total of 953 polluted river sites – taken from a total monitoring programme of 2,500 sites – were analysed with a view to identifying the main sources of pollution. These sites are all on rivers, but improving their water quality is also the key to improving water quality in lakes and transitional and coastal waters as well as improving groundwater status.
In broad terms approximately half of the 953 sites assessed are polluted due to what may be termed ‘large point sources’ such as municipal wastewater treatment plants. The other half are polluted as a result of diffuse sources, particularly agricultural activities, as well as a range of other activities such as forestry and peat harvesting.
Water Framework Directive
The seven River Basin Management Plans (RBMPs) submitted to the EU in 2010 include programmes of measures for the restoration or maintenance of the status of all water bodies by 2015, 2021 or 2027. The programmes of measures described in the RBMPs are effectively the application of the generic measures, listed below, in various combinations to some 5,500 water bodies:
- Controlling the inputs of phosphorus and nitrogen to waters
- Controlling inputs of oxygen using matter (e.g. silage, milk waste, sewage)
- Controlling pathogens in water
- Complete elimination of dangerous substances (priority substances) and control of specific pollutants to protect aquatic communities and human health
- Ensuring that there is a sufficient volume of water in all our water bodies
- Controlling hydromorphological conditions (physical characteristics of the shape and boundaries of the water body) both in-stream and along riparian zones.
Tackling Point Source Pollution
Point source pollution is easier to identify but more expensive to control than diffuse pollution. In many cases, the large point sources of pollution will require investment and infrastructure upgrades. 93 per cent of urban waste water discharges in Ireland currently receive secondary treatment or higher but 46 per cent of waste water treatment plants did not meet all waste water quality standards or EPA guidelines.
Tackling Diffuse Pollution
Agricultural activities associated with water pollution include land spreading of artificial fertilisers and animal manures in unsuitable climatic and ground conditions, silage effluent discharges, farmyard runoff, watering animals and poorly managed ring feeders. A range of actions are available to control water pollution under existing legislation. 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. This includes a code of Good Agricultural Practice (GAP) which is mandatory for all farms. The Department of Agriculture, Food and the Marine (DAFM) undertakes approximately 3,500 farm surveys each year under cross-compliance rules. However, the GAP Regulations are unlikely to be sufficient to protect high-status water bodies in all cases, and special sub-basin plans have been prepared for freshwater pearl mussel catchments.
Domestic Waste Water Treatment Systems
In most rural areas the majority of the population use on-site wastewater treatment systems such as septic tanks. If poorly sited and/ or not properly maintained, these systems can pollute groundwater, surface water and drinking water supplies and impact on human health. The EPA has published a revised code of practice for wastewater treatment and disposal systems in unsewered areas (EPA, 2010) that is referenced in revised building regulations and will be applicable for all new builds. New legislation dealing with registration and inspection of septic tanks was passed in 2012 (Water Services (Amendment) Act 2012). This legislation is Ireland’s response to a European Court of Justice (ECJ) ruling against Ireland in relation to on-site waste water treatment systems. The new legislation provides for the establishment of a registration system for domestic on-site waste water treatment plants and requires the EPA to put in place a national inspection plan in conjunction with the local authorities.
Over the years, water protection efforts have succeeded in reducing the extent of serious pollution in rivers from 174 km in 1971 to just 18 km in 2011. The main task now is to improve the status of some 4,000 km which is currently at less than good ecological status. With a focused programme, emphasising the same site-by-site approach that has worked well with the seriously polluted sites, progress can be made in achieving the status targets set out in the RBMPs under the WFD. Lake water quality has remained relatively static over recent decades, albeit with some dramatic reductions in chlorophyll levels due to the introduction of zebra mussels. Lakes will respond to measures to reduce nutrient inputs more slowly than rivers, but nonetheless the measures taken to address river pollution are also the key to improving lake water quality, as very few lakes have direct discharges into them.
Some improvements in the water quality of transitional and coastal waters have been noted due to the commissioning of new waste water treatment plants in coastal towns such as Sligo Bay and the Liffey estuary. There is still a significant lack of adequate treatment levels in many coastal towns, with 42 towns, important as tourist centres linked to water activities, without secondary treatment. The control of nutrient inputs from inland diffuse and point sources is also crucial in improving the water quality of estuaries and bays.
Overall, there is a continued need for improved protection of groundwater, especially in the context of achieving the WFD objective of good status for all waters by 2015. In some instances, it will not be feasible to meet this objective by this deadline, as it may take a number of years for the measures to bring about a reduction in concentrations of nutrients. This is because the nitrate and phosphate will require time to flush through the groundwater system. If all the basic and supplemental WFD measures are implemented, the objectives should be reached within the 2021 or 2027 extended deadlines.
Special protection measures are needed to protect and restore high-status waterbodies of all types, as they are susceptible to degradation due to pressures such as field drainage and fertilisation, tree planting, tree felling, house-building, onsite waste water treatment plants, insecticide usage, road building and wind farm construction. The impacts of these pressures are not always easily controllable under current legislation.
The development strategy for the agriculture sector, Food Harvest 2020 (DAFF, 2010) proposes a 50 per cent increase in milk production by 2020. While environmental sustainability is a key underlying principle of Food Harvest 2020, the milk production targets will present a significant challenge to meeting WFD objectives. It is vital that future agricultural practices be developed and implemented to be fully sustainable, and not prevent Ireland from meeting its EU obligations in relation to water.