EPA - Ireland's Environment, An Integrated Assessment - 2020

Ireland’s Environment – An Integrated Assessment 2020 Microbiological contamination The most important indicators of the quality of drinking water are the microbiological parameters, in particular the bacterium Escherichia coli ( E . coli ) and enterococci. The presence of E . coli and enterococci in drinking water indicates that the water treatment plant is not operating adequately or that faecal contamination has entered the water distribution system after treatment. The incidence of E . coli in public water supplies has significantly reduced from 87 in 2007 to only seven in 2019 due to improvements in guidance, controls and management of disinfection at water treatment plants. The number of supplies with enterococci failures remains low, with only two in 2019 compared with six in 2018. The microbiological quality of private water supplies remains inferior to that of public supplies. Many private wells are at risk of contamination from sources such as septic tanks, land-spreading of slurry, animals grazing near the wellhead, and chemical and fuel storage tanks. It is estimated that up to 30 per cent of private wells in operation in Ireland are contaminated with E . coli (EPA, 2017). Moreover, findings from EPA-funded research that assessed 212 private wells in four areas of the country found that only 35 per cent were properly protected against contamination (Gill et al. , 2018). Of particular concern is the continued and increasing prevalence of a particular strain of E . coli called Shiga-toxin/verocytotoxin- producing E . coli (STEC/VTEC), which produces a powerful toxin that can cause serious illness. Younger (< 4 years old) and older populations and those who are immunocompromised are particularly vulnerable to STEC/VTEC infection. Over the past decade, Ireland has consistently reported one of the highest incidences of STEC/VTEC in the EU, reporting ten times the EU average in 2017 (HSE HPSC, 2019a). Irish families are particularly vulnerable to this strain of bacteria because of the high proportion of rural dwellers who rely on private wells and septic tanks, the large cattle population and Ireland’s diverse geology and climate. Cryptosporidium and Giardia are genera of microscopic parasites found in human and animal waste that can cause gastroenteritis and persistent diarrhoea (contaminated water may come from lakes or ponds, swimming pools, drinking water or ice). While there is no overall trend for cryptosporidiosis in Ireland, the number of cases in 2018 (629 cases) was the highest reported since 2007. Ireland has consistently reported the highest crude incidence of cryptosporidiosis of any EU Member State since 2012. Contact with effluents from farm animals is the main risk factor for cryptosporidiosis. Health surveillance data show that people who are not served by public water supplies were over-represented in sporadic cases, relative to the distribution of households by water supply type nationally (HSE HPSC, 2019b). Figure 14.2 shows the number of cases of giardiasis reported in Ireland between 2004 and 2018 (HSE HPSC, 2019c), showing a six-fold increase in the last 6 years. There were 270 cases reported in 2018, which is the highest reported incidence in Ireland but is similar to the reported incidence at EU level. According to the HSE, the increase in recent years is believed to be largely due to changes in laboratory practice for selecting stools for testing coincident with the introduction of newer, more sensitive molecular detection techniques. Much remains to be learned about the true epidemiology of giardiasis in Ireland, but it is clear that it causes a much larger burden of disease than previously thought. Promoting best practice in the use of pesticides to protect drinkingwater Herbicide Use in Grassland Protecting Drinking Water from Pesticides APHA ANIMAL&PLANT HEALTHASSOCIATION Focus on MCPA and rush control BEWARE! Spraying rushes can very easily lead to breaches of thedrinkingwater standard for pesticides, particularly if usingMCPA products. Why? • MCPA iswater soluble and takes severalweeks tobreak down. • Rushes thrive inpoorlydrained areas (with awater table near the surface)which areprone to runoff tonearbywater bodies. What todo? • Use non-chemical controlmethods e.g. cutting, drainage, sward improvement. • If spraying, targetonly the rush affected areas. • If spraying, cut rushes onemonthbefore or one month after spraying to improve the effect of the spray. • Considerweedwipingwith an appropriateherbicide as a rush control option. REMEMBER! A SINGLE dropofpesticide lost toawater body such as a typical small stream (1metres wide, 0.3metresdeep), for example, can beenough tobreach the legal limit for pesticides indrinkingwaterof 0.1partper billion along 30 kmof its length. Always read and follow theproduct label. Beawareofhownearwaterbodies (ditches, streams,ponds, rivers, lakes, etc.),drainsor wells are towhere you areworking. Findout if the treatment area is in the vicinityof adrinkingwaterabstraction pointorwell. For further information on related topics such as container storage, triple rinsing, Integrated PestManagement or a listof approved PesticideAdvisors visit: www.pcs.agriculture.gov.ie ,www.teagasc.ie or www.epa.ie A SINGLE dropof herbicide can breach the drinkingwater limit in a small stream for 30 km 358