There has been no significant improvement in the water quality of rivers and lakes which is largely attributable to excess nitrogen and phosphorous, the Environmental Protection Agency (EPA) has said.
Nitrogen levels, mainly from fertilisers and manures, increased in rivers and groundwater last year, the Water Quality in 2022 – An Indicators Report published today (Wednesday, June 14) shows.
Nitrate concentrations are too high in 40% of river sites and in 20% of estuarine and coastal water bodies, which are found mainly in the south and southeast of the country.
This, the EPA said, is primarily attributable to intensive agricultural activities on freely draining soils, and most of the nitrogen in Irish waters comes from organic and inorganic fertilisers.
There is no indication that nitrate levels are reducing, the report states. In addition, phosphorus levels are too high in 28% of rivers and 36% of lakes which impacts on their biological quality.
Agriculture
The agriculture sector and Uisce Éireann need to take action to reduce the losses of both nitrogen and phosphorus nutrients to the environment, the EPA said.
Commenting that the “failure” to improve water quality in 2022 and over the longer term is “extremely disappointing”, director of the EPA’s Office of Evidence and Assessment, Dr. Eimear Cotter said:
“We will not meet our water quality objectives until nutrient levels are reduced in those areas where they are too high. Addressing this must be a priority for the agriculture sector and Uisce Éireann to reduce the losses of nutrients to water.
“While we can see improvements happening in some areas, these are offset by declines elsewhere, so overall there is no discernible change in the biological quality of our rivers or lakes in 2022.”
“We need to see full implementation of the Nitrates Action Programme through compliance promotion and targeted agricultural inspections,” EPA programme manager Mary Gurrie said.
Agricultural measures need to be targeted to the areas where they are needed and further measures to achieve this are required, according to the EPA.
Water quality
Excess nutrients entering water courses cause an overgrowth of plants and algae, which in turn clogs up water courses, uses up oxygen and harms fish and other aquatic life, the EPA said.
In total 1,317 of the river bodies assessed (56%) over the period 2019-2022 were in high or good biological quality. The remaining 1,045 river bodies (44%) were in moderate, poor, or bad quality.
The EPA said that the number of river water bodies in bad condition has now reduced to two:
- Annagh, Co. Clare where the cause of this recent deterioration is currently under investigation; and
- Laune, Co. Kerry where urban waste water is a pressure.
Last year, 671 out of 2,362 river water bodies were assessed of which 84 improved while 77 declined, according to the EPA report.
The quality of Ireland’s waters, and the issues impacting on water quality, can vary depending on the soils, geology, and the nature of human activities in a region, the EPA said.
Phosphorus is a particular problem in agricultural areas with poorly draining soil, while nitrogen leaching in the southeast is a problem for the estuaries along the southern seaboard, the EPA said.
The “Nitrate in Rivers” indicator in the EPA’s latest report is based on an assessment of average nitrate concentrations over three years (2020-2022) at 1,305 river sites.
Data for this three-year period for nitrate in rivers show that 40% of river sites nationally have unsatisfactory nitrate (NO3) concentrations (above 8 mg/l NO3), the EPA said.
The “Phosphate in Rivers” indicator used by the EPA is also based on an assessment of average phosphate concentrations over the 2020-2022 period at 1,305 river sites.
Data shows that 28% of sites have unsatisfactory phosphate concentrations while the remainder is at levels which support high (58%) or good (14%) water quality.
Phosphorus losses in these catchments come primarily from runoff losses from agriculture on poorly draining soils and from waste-water discharges, the EPA said.
Phosphate levels in rivers have been generally stable over recent years. The southeast and southwest regions both exhibit the highest river phosphate concentrations in the country.
In total 36% of lakes had unsatisfactory phosphorus concentrations, at levels that do not support good water quality between 2020-2022. The majority of these are in the border region.