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Water quality update

27 May 2016

​Ongoing testing shows that levels of the chemical Oxadixyl in Val de la Mare reservoir and the Val de la Mare west stream continue to rise in line with seasonal expectations. The increase is due to less dilution in the stream from rainfall as the drier summer months approach.

Samples of water tested are still well below the advisory World Health Organization (WHO) health-based limit for Oxadixyl and Jersey Water continues to select and blend water resources to ensure clean and safe public mains water supplies.  The treated water supplied by the company to its customers continues to meet all regulatory and health-based limits and remains safe for consumers.

Environmental Protection officers from the Department of the Environment are continuing to monitor the levels of Oxadixyl in private water supplies and all tests show they remain below the current advisory WHO-based health limit.

Officers from the Department of the Environment and Jersey Water are continuing to monitor the levels of Oxadixyl in streams in the west of the Island and its impact on Val de la Mare reservoir. 

New higher limit

Jersey initially followed a precautionary WHO advisory health limit for Oxadixyl of 3 ug/l (micrograms per litre). This is considered conservative. A revision to a new, higher level is expected to be set soon, following best practice elsewhere. The Water (Jersey) Law 1972 requires Jersey mains drinking water to contain no more than 0.5 ug/l of pesticides overall and no more than 0.1ug/l of any one pesticide.

Val de la Mare reservoir is still not in use by Jersey Water. The company will need to bring the reservoir back into service soon to secure the Island’s water supply during the summer months.

Once in service, Jersey Water will continue to blend water from around the island to offset the slightly higher levels of Oxadixyl levels in Val de la Mare. However, there may be occasions when levels in the treated water exceed the permitted regulatory limit of 0.1 ug/l. 

If there is any risk that regulatory limits may be exceeded, in accordance with the requirements of the Jersey Water Law, Jersey Water may apply to the Minister for the Environment for a temporary ‘dispensation’ or exemption under the law. The Minister must consult with the Minister for Health and Social Services before making a decision.

Dispensation application

The Minister for the Environment, Deputy Steve Luce said “any application for a dispensation will be precautionary at this stage. Jersey Water is currently drafting an application for a dispensation relating to Oxadixyl in case the water supply exceeds the lower regulatory limit during the drier summer. I want to assure people that I, the regulator and Jersey Water will be working together to ensure that any dispensation is actually used as infrequently as reasonably possible.” 

The level of the other previously detected pesticides in water has dropped off recently following the end of potato planting. But officers remain vigilant and will continue to regularly monitor water sources for those pesticides used by growers in case heavy rain causes a temporary increase.

The Minister and the department continue to work closely with farmers to minimise any detections during next year’s planting. 

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