The underground sources of drinking water in the Wakatipu Basin need better protection, an Otago Regional Council scientist says.
Aquifers under the Wakatipu Basin around Lake Hayes, Frankton Flats, the Shotover River and Mill Creek need to be managed to protect their important water supply roles, council groundwater resource scientist Jens Rekker says.
A report to the council this week recommended the basin's groundwater be divided into six distinct aquifers and protected by proposed groundwater protection, nitrogen-sensitive and allocation zones.
''The combination of nitrogen and waste controls would reduce the risk of contamination of good groundwater quality and allow continued drinking of bore water without significant treatment,'' Mr Rekker said.
The year-long investigation of the Wakatipu Basin aimed to provide guidance for groundwater management in the area.
As land use had changed from grazing to residential in the areas next to Queenstown and Arrowtown so had the water needs of the basin, he said.
The aquifers were now used for domestic, communal and individual water supplies, with little taken for irrigation or industry.
They were replenished by rainfall, rivers, creeks and springs.
It was suggested, given the high importance of the aquifers for drinking water supply, they be given groundwater protection zone A listing under the proposed Water Plan Change 6A (water quality), he said.
The groundwater protection zones would introduce controls for waste discharges and soil disturbance over defined aquifers.
Of the six aquifers, the Mid-Mill Creek aquifer was found to be over-allocated, Mr Rekker said.
Cr Michael Deaker said given the Windemeer aquifer was next to Lake Hayes, which had significant water quality issues, it was surprising it was not affected.
Mr Rekker said it was thought Lake Hayes was a natural glacial lake and its silted clay sealed it off from the downstream aquifer.
Cr Gretchen Robertson said with one aquifer already over-allocated, the area needed to be carefully managed. The report will now be considered by the council's policy committee.
