Nitrogen levels are too high in almost half of all Irish rivers – and a quarter of Irish groundwaters – according to the latest water quality report published by the Environmental Protection Agency (EPA).

This morning (Wednesday, July 14) the agency published the “Water Quality in 2020: An Indicators Report” which provides an assessment of the quality of Ireland’s rivers, lakes, estuaries and groundwaters.

According to the report, the main threat to water quality is high nutrient levels, such as phosphorus and nitrogen which come from human activities.

Many rivers, groundwaters and estuaries in the south, southeast and east of Ireland are under pressure from excess nitrogen from agricultural activities, the agency says. Almost half of Irish rivers (47%), a quarter of Irish groundwaters (24%) and one fifth of estuarine and coastal water bodies (21%) have nitrogen levels that are too high, the report noted.

It was highlighted that the levels impact the ability of these waters to sustain healthy ecosystems and cause nuisance algal blooms in our estuaries.

High nitrogen levels, above the drinking water standard, can pose a risk to human health.

Commenting on the report, EPA director of evidence and assessment, Dr. Eimear Cotter, said:

“Our water quality is currently under threat with nitrogen pollution from agriculture causing particular pressure in parts of the south, southeast and east of the country.

“Rivers such as the Bandon, Lee, Blackwater, Suir, Nore, Barrow and Slaney have nitrogen levels that are too high with significant implications for the marine environments they flow into.

“We urgently need to address nitrogen pollution so that we can protect and restore the water quality in these areas. If we do not substantially reduce nitrogen inputs to our rivers, and ultimately our marine environment, we are in danger of further deteriorations in water quality and losing our excellent coastal water quality.”

Just over half of Ireland’s rivers and lakes are in satisfactory biological quality which means that a large number are unable to sustain healthy ecosystems for fish, insects and plants, the report found.

The EPA noted that, while there are encouraging signs of improvements in the areas prioritised for action in the River Basin Management Plan, “a lot more needs to be done” to improve water quality.

In 2019 and 2020, 345 rivers showed improvements in quality, including an increase in the number of high-quality river sites – however, 230 rivers declined in quality.

Mary Gurrie, programme manager, added:

“While there has been an overall net improvement in the biological quality of rivers monitored in 2019 and 2020, EPA found that 230 rivers declined in quality.  It is a key requirement of the Water Framework Directive that we protect water quality and prevent deterioration. 

“The scale of declines is offsetting the improvements and hampering progress towards improving water quality. 

“It is essential that action is taken in both the next River Basin Management Plan and the Nitrates Action Programme to continue improvements whilst also preventing further deterioration,” Gurrie said.

The report is available on the EPA website and the accompanying data used in the water quality assessments are available on