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Early insights into river nitrogen levels indicate an increase in the first half of 2025

Date released: September 17, 2025

  • The EPA’s Early Insights Nitrogen Indicator report for the first half of 2025 shows that nitrogen levels in rivers have increased by 16 per cent since the same period in 2024.
  • Year on year, nitrogen levels fluctuate due to source loading, agricultural land management and weather patterns. The EPA is investigating the drivers that have caused these changes over time.
  • Nitrogen remains too high in the southeastern half of the country and further action will be needed to reduce concentrations to levels that support healthy ecosystems. 
  • Agriculture is the primary source of nitrogen in our waters. While significant work is underway in the sector, the scale and pace of action needs to increase.

17 September 2025: The Environmental Protection Agency (EPA) has today published the Early Insights Nitrogen Indicator report for the first six-months of 2025. The report has been developed to provide more timely information on nitrogen levels and is based on monitoring data for 20 major, representative rivers. Overall, the report shows that nitrogen levels have increased by 16 per cent in the first half of 2025, relative to the same period in 2024. 

The data show that nitrogen levels remain too high in the southeastern half of the country. Agriculture is the primary source of nitrogen in these areas. Targeted and sustained action will be needed in the higher risk, freely draining, agricultural areas to reduce nitrogen losses to waters before aquatic ecological health, and overall water quality will improve. The EPA Farm and Landscape measures for Agriculture (FLAG) map helps to identify where these highest risk areas are and will assist in identifying the types of actions that are needed. 

Commenting on the report, Dr Eimear Cotter, Director of the EPA, Office of Evidence and Assessment, said:

“The EPA continually strives to produce timely information and evidence on Ireland’s environment. Specifically, this publication responds to a need for early insights into trends in nitrogen levels. Agriculture is the primary source of nitrogen in Irish rivers and there is significant action underway within the sector to improve water quality. It is therefore disappointing to see this increase in nitrogen levels for the first six months of 2025 following reductions in 2024. It is important that the sector implement sustained actions to reduce nutrient losses in a targeted way.”

The latest edition of the Early Insights Nitrogen Indicator report is now available on the EPA website. Further information on local water quality, including the FLAG map to help target agricultural measures, is available here. 

Further information: Emily Williamson, EPA Media Relations Office 053-9170770 (24 hours) or media@epa.ie

NOTES TO EDITOR

EPA water quality reporting: The EPA undertakes a full assessment of the overall quality and ecological status of Ireland’s waters every three years. The latest full assessment was published in October 2022 and can be found on the EPA website. The next full assessment for the period 2019 – 2024 will be published in Q4 2025. 

The EPA also publishes water indicator data for over 1000 monitoring points from the national water monitoring network, on an annual basis. The latest report on Nitrogen and phosphorus concentrations in Irish waters 2024 was published in July 2025. 
In 2021 and 2025, the EPA published an assessment on the nitrogen reductions that were needed in major catchments to support healthy aquatic ecosystems. The most recent assessment can be found here and included data up to 2024. 

Water Body: A water body is an area of water, which is usually either the whole or part of a lake or coastal water, or a section of a river or an estuary (e.g. Lough Ree is one water body whereas the River Lee is divided into nine water bodies for monitoring purposes).

Nitrate: Nitrate is a form of nitrogen which is a nutrient and essential for plant growth. Too much nitrogen in a water body can lead to the over-growth of plants and algae that outcompete and displace other flora and fauna. This excessive growth can also cause oxygen depletion and damage the ecology of our water bodies. Our estuaries and coastal waters are particularly sensitive to high nitrogen concentrations. The main source of excess nitrate in the environment is agriculture, with wastewater also contributing. Nitrate concentrations above the Drinking Water Standard can pose a risk to human health, particularly for young children.

Phosphorus: Phosphorus is a nutrient which is essential for plant growth. As with nitrogen, too much phosphorus in a water body can lead to the over-growth of plants and algae which disturb the ecosystem. Excess phosphorus is a particular concern for the ecological health of rivers and lakes. The main sources of excess phosphorus in the environment are agriculture and wastewater.

Pressures impacting on waters: The EPA has published a series of reports on the main pressures impacting on waters which are available at Update on pressures impacting on water quality. Catchment level information on water quality is available here.

River Basin Management Plan: The River Basin Management Plan sets out the national policy and actions that are being taken by all sectors to improve and protect water quality. Further information about the National River Basin Management Plan is available on the Department of Housing, Local Government and Heritage website.

www.catchments.ie: A collaborative EPA, Local Authorities Water Programme (LAWPRO) and Department of Housing, Local Government and Heritage website that is used to share data, information, and resources on water in Ireland.