The Queenstown Lakes District Council is investigating the cause of a blocked sewer pipe, which led to a discharge of waste water into Lake Wakatipu via a drain into Horne Creek this morning.
The blockage has been removed, the foreshore where Horne Creek discharges into the lake is being disinfected, and water quality testing is under way.
Council estimates about 5000 litres of contaminated water entered the lake at the southern end of Queenstown Bay.
Council infrastructure and assets general manager Erik Barnes said as a precaution, a small area of beach around the Horne Creek outlet would be closed today and testing would be undertaken throughout the day,
Because of the blocked pipe, pressure had forced the liquid up through a manhole.
It was too soon to say what had caused the overflow, but contractors who had cleared the blockage said that there appeared to be gravel and stone, possibly from construction debris, in the pipe.
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