An extensive study by the Environmental Protection Agency has found raised levels of nitrogen in Lough Swilly.
The scenic Swilly waterway, which separates Inishowen from the Fanad peninsula, has been listed as one of four water bodies that have seen “significantly increased” nitrogen concentrations from 2012 to 2022.
Mulroy Bay in County Donegal is also one of the four cited for increased nitrogen.
The EPA’s ‘Water Quality in 2022 – An Indicators Report’ was published last Wednesday.
The report states that one of the most significant stressors on water quality and ecosystem health is high nutrient levels, such as nitrogen and phosphorus.
These nutrients can enter our waters as a result of human activities such as agriculture, waste water and forestry.
The EPA’s assessment shows no significant improvement nationally in the biological quality of rivers and lakes in 2022, which is largely attributable to excess nitrogen and phosphorous.
Overall, nitrogen levels in rivers and groundwater increased between 2021 and 2022. Nitrogen is too high in 40 percent of river sites and in 20 percent of estuarine and coastal water bodies. In addition, phosphorus levels are too high in 28 percent of rivers and 36 percent of lakes.
Increased nitrogen concentrations in these waters is an indicator of human activities in the upstream catchments affecting water quality. Too much nitrogen in a water body can lead to the overgrowth 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, the EPA warns.
The report found that 21 of the 103 estuarine and coastal water bodies assessed were in “unsatisfactory condition” for nitrogen.
No such unsatisfactory levels have yet been detected in Inishowen though, despite the rising nitrogen levels over the past decade in Lough Swilly.