Boil-water notices were lifted from Glendhu Bay and Arrowtown yesterday.
Queenstown Lakes District Council capital works manager Ken Gousmett said the low levels of E.coli detected recently at the Glendhu Bay Water Treatment Station, which services the Glendhu Bay Lakeside Holiday Park, were a ''minor transgression''.
A boil-water noticed was issued to campers 12 days ago, but results from water samples had been clear for the past week. The council and camp managers had opted to leave the boil-water notice in place beyond the required three consecutive days of clear samples as a precaution, Mr Gousmett said.
While further testing would be carried out to confirm the cause of the contamination, the suspected source was run-off - resulting from recent heavy rain - travelling down the Alpha Burn stream which passes through the camp. The bacteria could have come from any warm-blooded animal living in the stream catchment.
''It helps if we can isolate the source, then we can plan better for it,'' Mr Gousmett said.
QLDC communications manager Meaghan Miller said council staff had not identified a definitive cause of the low level E.coli discovered on Friday after mandatory testing of the Arrowtown water supply, which comes from a bore.
''The Arrowtown community has historically chosen to have an untreated supply, given that the river gravels act as a natural filter. Regardless, the supply is tested on a regular basis,'' Ms Miller said.
''On occasion, particularly after heavy rain, there has been an issue with the supply but it is not a common event. The bore supply has on the whole proved to be excellent. Council will mitigate any potential issues when it installs a UV treatment system, which is funded next year.''
