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Water quality update

25 January 2018

​Nitrate levels in untreated surface water in Jersey continue to fall but high rainfall has led to an increase in pesticide levels in surface water near Handois Reservoir.

Recent test results show the Island’s water quality continues to improve and that nitrate and pesticide levels in steams are on a long-term downward trend. This follows a number of measures introduced in recent years to improve Jersey’s water quality as a result of a partnership between Island farmers, Jersey Water and the Department of the Environment through the Action for Cleaner Water Group.

Tighter voluntary controls on the use of some pesticides in certain areas and more targeted application of pesticides and fertilisers are in place for the 2018 potato season, following the success of a trial farmers carried out last year to apply fertiliser more precisely.

Precision placement

In 2018, farmers are expected to plant approximately 80% of potatoes using specialised machines part-funded by the Department of the Environment’s Countryside Enhancement grant scheme. These machines place fertiliser where it is needed, rather than spreading it across the field in the traditional broadcast method.

However, there is concern about a recent increase in pesticide traces in surface water caused by heavy rainfall. While the number of pesticide breaches recorded by Jersey Water in Island streams has been similar to last year, the high rainfall has contributed to higher than usual traces of boscalid, metribuzin and azoxystrobin in untreated surface water near Handois reservoir, which is now out of service. Mains drinking water supplied by Jersey Water remains clean and safe.

Viable industry

The Minister for the Environment said ‘I’m pleased with the continued close dialogue and co-operation of our farmers who have gone the extra mile to improve the way they work. However, although the overall trend is positive, there are still occasions when we’re picking up pesticide traces over the regulatory limits. We will continue to investigate these to get the balance right – to ensure we have a viable industry with a minimal negative impact on the environment.

‘With the heavy rain likely to continue for a while, I urge farmers to check the forecast before spraying; not to spray on water logged fields to reduce the chance of run off; and to take care in choosing the right fields to apply slurry for maximum benefit and minimum environmental impact.’

Close monitoring

The potato season isn’t yet in full swing and the area in which exceedances were recorded has not yet been planted with potatoes. Officers will be monitoring water quality closely in the coming weeks and, as usual, investigating any significant traces of pesticides in untreated surface water.

Levels of the historically-used pesticide oxadixyl in public and private water supplies continue to be monitored. All tests show they remain below the current advisory World Health Organization-based health limit. However, the rising groundwater levels due to the recent rain may cause both nitrates and oxadixyl levels to increase in future test results. 

Audax report

Surface water streams are regularly checked for both pesticides and nitrates. The findings are discussed at the joint government/industry ACWG meetings with recommendations being made to improve. ACWG continues to monitor, adjust and put into place the recommendations of the Audax report which include:

  • tighter controls on pesticide use in certain sensitive areas, such as Val de la Mare, Queen's Valley and Handois catchments
  • using less fertiliser (with a lower phosphate content)
  • targeted use of less soluble pesticides by farmers
  • expanding areas for trials (such as the use of slow-release fertiliser)
  • the introduction of new machinery to provide more precise application of pesticides and fertiliser
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