Three pesticide exceedances in Donegal drinking water supplies in 2021

Three exceedances of the pesticide Bentazone and MCPA have been detected in the public drinking water supplies in Buncrana, Donegal (River Eske) and Fanad East (Shannagh) in 2021

These exceedances were detected as part of Irish Water’s public water supply monitoring programme. MCPA is still the most commonly detected pesticide in drinking water sources and is present in many commonly used herbicide products used to control thistles, docks and rushes.There was a slight reduction in the number of exceedances for pesticides in public drinking water supplies in Donegal last year, according to Irish Water. In 2020 the utility detected four exceedances for MCPA and 2,4-D as part of its ongoing monitoring, however, this had reduced to three exceedances in 2021.

The Buncrana, Donegal (River Eske) and Fanad East (Shannagh) water supplies abstracts raw water from Lough Doo, River Eske and Shannagh Lake respectively, all of which are vulnerable to runoff from land. Irish Water is asking users of any herbicide or pesticide products to continue to consider the vulnerability of their local drinking water supplies to pesticide contamination and the importance of these supplies to local homes and businesses in the community.

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Irish Water, working in partnership with a range of organisations involved in the NPDWAG, is asking the farming community, greens keepers, grounds keepers, and also domestic users of pesticides, to consider in each case whether they need to use pesticides at all. Minimising pesticide use not only helps to protect water quality but also has wider environmental benefits. For example, leaving areas unsprayed can help native flowering plant species to grow and support a range of insects including bees and other vital pollinators. One third of Ireland’s bee species are threatened with extinction and by helping the bee population survive and thrive we are also helping to protect our precious water sources. For more information on practical ways to help bees and other pollinators, check out the All-Ireland Pollinator Plan at Farmers should also bear in mind that application of herbicides reduces sward species diversity and could negatively impact on payments in future agri-environmental schemes.

A tractor and sprayer.

Where pesticide use is considered necessary, the NPDWAG is working with local communities to ensure that best practice measures to protect drinking water sources and biodiversity are always followed. Farmers and other landholders dealing with the challenge of rushes should note Department of Agriculture, Food and the Marine (DAFM) guidance on the sustainable management of rushes. This approach is based on the concepts of containment or suppression, and aims to minimise the use of pesticides. More information on this can be obtained from your local farm advisor or on

The NPDWAG is chaired by the DAFM and involves key stakeholders from a range of Government departments and agencies, local authorities, industry representative bodies, farming organisation, water sector organisations and amenity sector organisations.

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Dr Pat O’Sullivan, Irish Water’s Regional Drinking Water Compliance Specialist said: “In Co Donegal, the exceedances of the drinking water regulations for MCPA and Bentazone were noted in the Buncrana, Donegal (River Eske) and Fanad East (Shannagh) public water supplies following routine sampling. While our consultation with the HSE has concluded that the levels we are detecting do not represent a threat to public health, they are still however undesirable in drinking water and it is therefore imperative that users of pesticides are mindful of best practice when using herbicides or pesticides and seek out alternatives.”

Adding to this, Dr Aidan Moody, DAFM and Chair of NPDWAG commented: “We need the continued engagement of all stakeholders, working in partnership, make further progress. Users of pesticides must always consider alternatives in the first instance and if the application of pesticides is considered essential make sure that they follow best practice measures to protect water quality.”If pesticides have to be used, the basic steps to reduce risks to drinking water sources and the aquatic environment are:

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Choose the right pesticide product (note that products containing MCPA are NOT approved for use in weed-wipers, and are not permitted to be used from the end of September until the beginning of March)

Read and follow the product label

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Determine the right amount to purchase and use

Don’t use pesticides if rain is forecast in the next 48 hours

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Make sure you are aware of the location of all nearby water courses

Comply with any buffer zone specified on the product label to protect the aquatic environment. Mark out the specified buffer zone from the edge of the river or lake or other water course and drainage ditches

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Avoid spills, stay well back from open drains and rinse empty containers 3 times into the sprayer.

Store and dispose of pesticides and their containers properly.

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Never fill a sprayer directly from a water course or carry out mixing, loading or other handling operations beside a water course

A video on the best practice use and application of products containing MCPA can be viewed on Irish Water’s YouTube channel at

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Information leaflets on pesticide use are also available to download from the Teagasc website at

A guide providing 10 easy steps towards responsible pesticide use in public and amenity and garden areas is available at