River nitrogen levels in Ireland are rising again. The Environmental Protection Agency (EPA) reports that nitrogen in major rivers rose 4.3% year on year in early 2026. That marks a second year in a row of increases. Pressure is heaviest in the south and south-east, where intensive farming and free-draining soils let nitrogen move easily into water.
The findings arrive as the slurry closed period starts on 1 October. For farmers, well owners and anyone who depends on local water, the message is the same. Nitrogen losses are not falling, and the effects reach from rivers to drinking water.
Table of Contents
What the EPA’s Early Insights Nitrogen Report Found
The EPA publishes its Early Insights reports every six months. Each one tracks nitrogen at 20 representative monitoring sites on Ireland’s major rivers. The aim is to flag national trends before a full year of data is available.
The January to June 2026 data shows average nitrogen concentrations rose 4.3% year on year. This follows a 10% rise in river nitrogen levels across 2025.
Roni Hawe, Director of the EPA’s Office of Evidence and Assessment, said the results “will be disappointing for many.” The EPA says more work is needed to turn action on farms into cleaner water. All sectors are now reviewing their measures ahead of Ireland’s next Water Action Plan.
Why River Nitrogen Levels Keep Climbing
The EPA points to a mix of source loading, land management and weather. Source loading means the nitrogen applied to land, most of it from chemical and organic fertilisers. The full report sets out the key factors behind the 2024 to 2026 trend:
- Fertiliser sales rose 10.6% in 2024 and a further 12.5% in 2025. Department of Agriculture figures show a further 7.3% rise in the six months to March 2026.
- The national herd shrank by 3.3% between 2023 and 2024, and by a further 0.4% in 2025. Fewer animals mean less manure, yet river nitrogen still climbed.
- Rainfall was above average in five of the first six months of 2026. River flows were above normal for most of that period, and 2025 was wetter than 2024.
- A hydrogeological lag slows the movement of nitrogen through soil and groundwater. Farm practices and weather in one year affect river levels in the years that follow.
Fertiliser sales do not measure how much fertiliser farmers spread, the EPA notes. Farm practices and soil type also shape losses. But sales remain a key indicator of how much nitrogen enters the system.
The South-East Carries the Heaviest Nitrogen Load
Nitrogen pressures are greatest across the east, south and south-east. Here, intensive farming, free-draining soils and local weather combine to push nitrogen into water. Catchments in the west and north-west remain below levels that harm river ecology.
Stations on the River Lee, Bandon and Blackwater in Cork were among those with higher concentrations. Lower catchment stations on the Shannon, Corrib and Liffey also recorded increases.
The EPA says the rise in lower-risk catchments suggests national factors, such as weather and fertiliser prices, played a part. But the far higher levels in the south-east point to local drivers like soil type and farm intensity. The EPA’s FLAG map shows where farm measures are most needed.
What Rising Nitrogen Means for Rivers and Drinking Water
Excess nitrogen fuels algal overgrowth. This depletes oxygen in the water and damages habitat for fish and other species. Estuaries and coastal waters are the most sensitive to high nitrogen.
The risk does not stop at rivers. Nitrogen reaches water through surface runoff and leaching into groundwater. Groundwater feeds private wells, and the EPA notes that many parts of Ireland have high groundwater vulnerability.
In drinking water, nitrogen shows up as nitrate. The legal limit is 50 mg/l under the European Union (Drinking Water) Regulations 2023. High nitrate levels pose the greatest risk to infants, as nitrate can reduce the blood’s ability to carry oxygen.
Public supplies are tested and treated. Private wells are the owner’s responsibility, and nitrate cannot be seen, smelled or tasted. Rising river nitrogen levels in your catchment are a signal to check your well.
Nitrate Testing With Southern Scientific
The EPA’s next Early Insights report is due in March 2027 and will cover July to December 2026. National data cannot tell you what is in your own well or on your own land.
Southern Scientific’s INAB-accredited (ISO 17025) laboratory tests for nitrate, ammonia, E. coli and coliforms in a single sample with our Standard Drinking Water Test. For farmers, our soil and slurry testing services provide the data needed to plan nutrients with precision.
As river nitrogen levels climb for a second year, regular nitrate testing is the clearest way to protect your water and your land. That means moving from reactive crisis management to proactive protection.
Nitrate Testing With Southern Scientific
The EPA’s next Early Insights report is due in March 2027 and will cover July to December 2026. National data cannot tell you what is in your own well or on your own land.
Southern Scientific’s INAB-accredited (ISO 17025) laboratory tests for nitrate, ammonia, E. coli and coliforms in a single sample with our Standard Drinking Water Test. For farmers, our soil and slurry testing services provide the data needed to plan nutrients with precision.
As river nitrogen levels climb for a second year, regular nitrate testing is the clearest way to protect your water and your land. That means moving from reactive crisis management to proactive protection.
