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Pesticides detected in South Leitrim (Mohill) public drinking water supply

13 June 2023

Public urged to consider alternatives to pesticides to protect the Shannon River – your drinking water source

An exceedance for the pesticide MCPA has been detected in the public drinking water supply in Mohill, Co Leitrim. MCPA is an active substance present in many commonly used herbicide products used to control the growth of rushes and docks. The exceedance was detected as part of Uisce Éireann’s public water supply monitoring programme.

The South Leitrim (Mohill) public water supply abstracts raw water from the Shannon River which is vulnerable to runoff from land and where there has been an increased level of pesticide detections noted in the catchment this year. Uisce Éireann is asking users of any herbicide or pesticide products in these catchments to consider the vulnerability of the water supplies to pesticide contamination and the importance of this supply to the local homes and businesses in the community.

Uisce Éireann, working in partnership with a range of organisations involved in the National Pesticides and Drinking Water Action Group (NPDWAG), is asking the farming community, green keepers, grounds keepers, and domestic users, to consider in each case whether they need to use pesticides at all. Pesticides must only be used where strictly necessary and only after the possibility of using other control methods has been carefully considered. Minimising pesticide use not only helps to protect water quality but also has multiple 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 polllintors.ie 

Where pesticide use is considered necessary, the NPDWAG and local catchment-based focus groups work with the community 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 tackling rushes should note the 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. Where pesticide use is considered necessary, please contact your local farm advisor. Further information is available at www.pcs.agriculture.gov.ie/sud/waterprotection

The efforts to reduce the incidence and level of detections are being coordinated by the NPDWAG. This group 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. 

Thomas Gibbons, Uisce Éireann said: “In Co Leitrim, an exceedance of the drinking water regulations for MCPA was noted in the South Leitrim (Mohill) public drinking water supply following routine sampling. While our consultation with the HSE has concluded that the levels seen do not represent a threat to public health, it is however undesirable and 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: “The active engagement of all stakeholders, working in partnership, is needed to tackle this issue. Users of pesticides must always consider alternatives in the first instance and if pesticide use 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:

  • Always seek advice from your local pesticide advisor
  • Choose the right pesticide product (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
  • Don’t use pesticides if rain is forecast in the next 48 hours
  • 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
  • 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.
  • Never fill a sprayer directly from a water course or carry out mixing, loading or other handling operations beside a water course

Further guidance:

A video on the best practice use and application of products containing MCPA can be viewed on Uisce Éireann’s YouTube channel.

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