E coli out­break cause not fully de­ter­mined

Central Otago Mirror - - NEWS - By CHE BAKER

An Otago Re­gional Coun­cil in­ves­ti­ga­tion into an e coli con­tam­i­na­tion in Lake Hawea’s retic­u­lated wa­ter sup­ply has proven in­con­clu­sive, but a coun­cil en­gi­neer be­lieves stock ef­flu­ent was the cause.

Coun­cil en­vi­ron­men­tal of­fi­cer Stephen Smith said the in­ves­ti­ga­tion was con­ducted about two weeks af­ter the con­tam­i­na­tion was found on Jan­uary 7.

At a Wanaka Com­mu­nity Board meet­ing on Jan­uary 28 Queen­stown Lakes District Coun­cil in­fra­struc­ture en­gi­neer Ni­cola Greaves told the board the con­tam­i­na­tion was likely caused by nearby stock ef­flu­ent.

‘‘Find­ing out the cause two weeks later is dif­fi­cult to con­clude,’’ Mr Smith said.

Sev­eral fac­tors could cause e coli con­tam­i­na­tions in­clud­ing bac­te­ria found in hu­man, an­i­mal and bird fae­ces.

There was ev­i­dence of ‘‘pug­ging and ero­sion of the river bank’’, Mr Smith said.

He spoke to the farmer of the land who was adamant there had not been stock in the area since Septem­ber. While it was not an of­fence to have stock in the lake or river, it was if it caused con­tam­i­na­tion.

The area was a ‘‘ mi­nor trib­u­tary’’ and ‘‘swampy en­vi­ron­ment’’ and could stay static for a very long time, Mr Smith said.

‘‘The wa­ter doesn’t run reg­u­larly down it,’’ he said.

The in­ves­ti­ga­tion, while ‘‘cer­tainly jus­ti­fied’’, could not con­clude what the cause was.

The farmer was pro­vided with in­for­ma­tion about his obli­ga­tions un­der the wa­ter qual­ity rules.

The Queen­stown Lakes District Coun­cil has in­di­cated the town’s wa­ter sup­ply should start to be taken from new un­der­ground bores lo­cated at Scott’s Beach from mid-year.

The wa­ter would be sub­ject to UV treat­ment only and should elim­i­nate the need to have pe­ri­odic chlo­rine treat­ment, which has been re­quired in the past when e coli con­tam­i­na­tion had been de­tected in the wa­ter sourced di­rectly from the lake.

Eil­ish Keane started at Wanaka Pri­mary School on Fe­bru­ary 3.

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