The Environmental Protection Agency (EPA) has said that their new findings will be "disappointing" for many, considering the amount of work farmers have put into reducing nitrates losses to water.

The agency today (September 16) published its Early Insights Nitrogen Indicator Report, which provides an early indication of trends in river nitrogen levels based on the first six months of the year.

Average nitrogen concentrations at representative monitoring locations in 20 major rivers increased by 4.3% in the first half of 2026 compared with the same period in 2025.

This follows an increase in river nitrogen levels between 2024 and 2025.

When too much nitrogen gets into rivers, lakes, estuaries, or coastal waters, it can cause an overgrowth of algae which depletes oxygen and impacts the habitat for other species.

According to the agency, the greatest nitrogen pressures remain concentrated in the south-eastern half of the country, driven largely by agricultural activities.

It said that reducing these pressures will require targeted action in the most vulnerable catchments, particularly where farming intensity is high and free draining soils allow nitrogen to move readily to waters.

Factors influencing nitrogen levels

According to the EPA, nitrogen levels fluctuate year on year due to a combination of factors, including source loading, agricultural land management, and weather patterns.

Source loading means inputs of nitrogen to the environment, the vast majority of which comes from chemical and organic fertilisers utilised in farming.

Different factors may be dominant in different catchments, depending on its physical characteristics.

Rainfall and river flow influence how nitrogen is transported to watercourses, and the resulting in-stream concentrations.

Periods of high rainfall may increase nitrogen losses through leaching, or reduce concentrations through dilution, depending on catchment soil properties and underlying geology, the EPA said.

‘Disappointing’

Director of the EPA office of evidence and assessment, Roni Hawe said the report higlighted that more work needs to be done.

He said: “These results will be disappointing for many, given the greater focus in recent years on reducing nitrogen losses to water and the work being undertaken by farmers, industry and other stakeholders to address the issue.

“While there has been growing engagement and a stronger emphasis on targeted measures, these findings highlight that more work is needed to translate actions on the ground into improvements in water quality.

“There is also a need for stronger joining up of policy and practice, recognising that measures to improve water quality can deliver wider benefits for agriculture, biodiversity and climate.”