EPA - Ireland's Environment, An Integrated Assessment - 2020

Ireland’s Environment – An Integrated Assessment 2020 Figure 13.2  Significant pressures on Ireland’s aquatic environment River Lake Coastal Estuarine Groundwater Agriculture Hydro- morphology Urban waste- water Forestry Other Domestic waste- water Urban run-off Peat Industry Mines and quarries 0 100 200 300 400 500 600 700 800 2,069 Land Use in Ireland Agriculture Forest Urban Other Water Quality and Agriculture Nutrient pollution (caused by too much nitrogen and phosphorus in our waters) is the key water quality issue impacting on our rivers, lakes and estuaries. Nutrient loss to waters can lead to excess growth of algae and plants, which in turn leads to eutrophication of rivers, lakes and marine waters. Phosphorus is typically the key nutrient associated with eutrophication of rivers and lakes, while excess loss of nitrogen impacts on estuaries and coastal waters (EPA, 2018a). Agriculture, as the most prevalent land use in Ireland, exerts the most pressure on water quality (Figure 13.2), impacting on just over half (780) of the 1452 water bodies that are ‘at risk’ of not achieving their water quality objectives (EPA, 2019b). The EPA’s most recent report on water quality in Ireland (EPA, 2019b) found that water quality has declined. Two of the main issues driving this deterioration are the excessive levels of nutrients and sediment entering our water courses. Land management practices, including agriculture, forestry and peat extraction, all contribute to this problem. In particular, increased agricultural activity in recent years, through increased cattle numbers and fertiliser use, has led to increased nutrient loadings, which in turn impact negatively on water quality (Figure 13.3). Significant improvements in controlling nutrient losses from agricultural point sources have been made over the last decade, with investments being made in increased storage capacity and improved farm infrastructure. However, significant challenges remain with regard to the control of diffuse losses of nutrients from land, arising from chemical and organic fertiliser use. Diffuse phosphorus losses occur most often from overland flow on poorly draining (heavy) soils. These types of heavy soils are common in parts of Cavan, Monaghan, Wexford, Limerick and Meath. Only a very small amount of phosphorus needs to be lost relative to the amount used on the land to cause water quality problems. The best solutions are therefore measures that break the pathway connecting the nutrient source to the watercourse. Examples of these measures include buffer zones, hedges, farm ponds and management of ditches. On the other hand, diffuse losses of nitrogen occur in freely draining soils where nitrogen easily infiltrates through the soil into groundwater before being discharged into river systems and onwards to estuaries and coastal waters. This is a concern for Cork, parts of Tipperary, Kilkenny, Carlow and parts of Wexford. In these areas the solutions centre on using less nitrogen fertiliser and using it more efficiently. 336