The number of public drinking water supplies where pesticides were detected above permitted levels has increased, according to a new report.
The Environmental Protection Agency’s (EPA) Drinking Water Quality in Public Supplies 2020 report shows that 33 locations around the country had elevated levels of pesticides.
That is an increase from the 27 public supplies that failed to meet the standard in drinking water regulations in 2019.
The EPA said this is “indicative of the common usage of pesticides”.
Herbicides
The EPA said that pesticides are detected in drinking water supplies due to incorrect use of such products in the catchment area of water bodies used for drinking water abstraction.
It noted that the term ‘pesticides’ includes a large range of products.
However, the EPA said that in Ireland it is herbicides that are the most commonly found pesticides in drinking water supplies, in particular MCPA10, which is used to control rushes.
In cases where supplies fail to meet standards due to the presence of pesticides, the EPA said that monthly monitoring is carried out during the spraying season from April to November.
A supply is deemed by the agency to have a persistent pesticide problem if failures are found during four or more of the monthly sampling events.
A supply may be placed on the Remedial Action List (RAL) if failures are persistent and initial investigations fail to resolve the issue.
The list includes supplies that are deemed ‘at risk’ by the EPA where the safety or security of supply is not acceptable.
Irish Water is required to put an action plan in place to resolve issues for each of these supplies.
Pesticides
The report stated that MCPA was found in two-thirds of the supplies that fell below the standard.
“One supply (Foynes/Shannon Estuary in Co. Limerick) had persistent pesticides failures during 2020,” the EPA stated.
This supply was added to the RAL.
At the end of 2020, the EPA said that there were six supplies on the RAL because of pesticides.
The agency called on Irish Water to implement its Interim Pesticide Strategy, which was published last July, and for the utility to consider treatment options where other measures failed to achieve compliance.