One of the main problems damaging the quality of surface waters is nutrient pollution caused by too much nitrogen and phosphorus in the water. A third of rivers and lakes and a quarter of estuaries have too much nutrient in them and there is also evidence that nutrient concentrations in rivers and nutrient inputs to the marine environment are increasing. At least a quarter of river sites have increasing nutrient concentrations while nitrogen and phosphorus loads from the land to the sea have increased by 16% and 31%, respectively. These nutrients cause excessive plant and algal growth in our rivers and increase the likelihood of harmful algal blooms in our lakes and estuarine waters.
Loss of nutrients from agriculture have increased in recent years as a result of the ongoing expansion of the agriculture sector under Food Harvest 2020 and its successor Food Wise 2025. In areas with freely draining soil, nitrate losses are closely correlated with farm intensity; the higher the application of nitrogen, the higher the nitrate concentrations in waters. Since 2013, nitrogen emissions have increased as both cattle numbers and fertilizer use have increased. Agricultural land can also be an important source of phosphorus particularly from poorly draining soils. Diffuse phosphorus losses from agriculture are difficult to tackle as the sources do not occur uniformly in the landscape, but from ‘hot spots’ or critical source areas.
Putting measures in place to address these additional nutrient inputs will be critical to reverse the current downward trend in water quality.
Urban waste water is one of the most common pollution pressures. Over half (56%) of the combined sewage loading that arises in large urban areas in Ireland is discharged from plants that are not meeting the required European standard. In 2021 untreated waste water, commonly referred to as raw sewage, still flows into the environment every day from 34 towns and villages because these areas are not connected to treatment plants. Thirty three of these areas are not scheduled to receive treatment until after 2022. Furthermore, improvements have yet to be identified and scheduled at 23 areas where waste water is the sole significant pressure on water bodies at risk of not meeting their environmental objectives. Continued investment in infrastructure is essential to provide the waste water treatment necessary to protect receiving waters and meet obligations under EPA authorisations and European Directives.
Irelands coastal and marine waters are clean and reasonably healthy but not as biologically diverse or productive as they could be. Our marine and coastal areas are impacted by several human-induced pressures including fishing, eutrophication, climate change and litter. These issues put pressure on our fragile marine systems.
Recent Water Framework Directive assessments (2013-2018) show that 80% of our coastal water bodies and 38% of our transitional water bodies are in high or good ecological status. Irelands offshore marine waters show no evidence of nutrient pollution.
Intensive fishing has threatened the stocks of many commercial fish and shellfish species. A transition to sustainable fisheries, and strict adherence to catch limits is imperative to ensuring not only the continued availability of this resource, but also the health of the associated food webs. In addition, Ireland's international commitment under the UN Convention on Biological Diversity to designate 10% of its marine area as marine protected areas (MPAs) by 2020 has not been met. Designation of marine protected areas has been recognised as a key mechanism to halt the loss of marine biodiversity and protect marine ecosystems.
Climate induced changes in marine temperature and pH have been recorded in Irish marine waters. Sea level rise has been recorded around Ireland’s coasts and coupled with increased storm frequency, poses a serious risk to Ireland’s coastal cities. Continuous monitoring, assessment and modelling are essential to assist in the planning of proper adaptation to sea level rise.
Microplastics can be found throughout our marine waters. Marine life can be physically impacted through entanglement and ingestion of plastics and litter. Ingestion may also provide a pathway for the transport of harmful chemicals into marine food webs.
Ireland needs to ensure the proper knowledge base and legislative framework is in place to protect our marine ecosystems as well as the services they provide.