Ireland's State of the Environment Report 2024

199 Chapter 8: Water As well as through direct discharges, nutrients can find different pathways into our waters depending on the landscape and soil type. Nitrogen tends to move down through freely draining soils until it meets the water table. From there, it makes its way horizontally underground in groundwater until it reaches a watercourse and eventually the downstream estuary. Phosphorus tends to move overland, carried by run-off on wet and heavy soils. Nitrogen. Nitrate concentrations are too high in 42% of river sites and 17% of estuarine and coastal water bodies (EPA, 2024a). This excess nitrate is damaging the ecological health of many of our estuaries and nearshore coastal waters. In particular, nitrate concentrations are too high in the south-east and southern region of Ireland (Figure 8.8). Annual average nitrate concentrations generally increased in these areas from about 2013 and peaked in 2018/2019, following a combination of excess nitrogen use and a drought year. There have been year- on-year fluctuations since 2020 but no real improvement overall. Concentrations remain too high, especially in the east, south-east and south. Figure 8.8  Average river nitrate concentrations, 2021–2023 Source: EPA, 2024a