Reservoir closed after chemical is discovered
Jersey Water stopped using Queen’s Valley as a precautionary measure for two weeks.
Chief executive Helier Smith said: ‘We detected metrabusine [weedkiller] in our routine testing but we don’t know where it came from as there was no planting taking place in that area at the time, so the Environment Department is conducting an investigation.’ Jersey Water also had to close Handois reservoir in St Lawrence six weeks ago, after the level of pesticides in a stream in its catchment area exceeded the regulatory drinking water quality standards.
Mr Smith said they began drawing water from Handois for treatment last Friday before releasing it into the Island’s mains water supply.
He said: ‘We have been monitoring the stream that feeds Handois and passing it by the reservoir for a number of weeks until the level of chemicals was low enough.
We then started putting it back into the reservoir to dilute it down and we also allowed the reservoir to fill and overflow for a number weeks to dilute it further.’ These are the first serious water pollution incidents since high levels of farming chemicals were detected around the Island two years ago.
Val de la Mare was closed for five months in March 2016 and Jersey Water had to divert polluted streams around its other reservoirs to maintain a safe drinking supply to Island homes.
Since then, farmers have been working with Jersey Water and the Environment Department to clean up the Island’s surface water sources through the Action for Cleaner Water Group.
Mr Smith said that Jersey’s regulatory drinking water limit for farming chemicals was 0.1 micrograms per litre, which is consistent with limits applied in the UK and across the EU.
When chemical levels exceed that limit, the company stops drawing water from that source, or blends it with other water sources to reduce the contamination to safe levels, before sending it to its treatment works.