May 13, 2014 9.45am

High water levels in Lakes Wakatipu and Wanaka

Heavy rainfall is expected in the headwaters of the Lake Wakatipu catchment over the next 24 hours. Lake Wakatipu has already risen by more than a metre since mid-April, due to a succession of heavy rainfall events in the catchment headwaters.

Whilst the additional rainfall over the next few days is likely to result in further lake level rise, low-lying parts of the lakeside communities of Glenorchy, Queenstown and Kingston are unlikely to be affected based on current forecasts and modelling.

The potential for minor flooding of low-lying areas around Queenstown occurs once the lake reaches 311.30m.

Lake Wanaka is expected to rise to around 279.2m. Surface flooding is possible there at 280m.

ORC director of hazards, engineering and science Dr Gavin Palmer said based on current predictions flooding of the townships was not a high risk. However, rainfall predicted for the next 24 hours would push the lakes’ levels up to near surface flooding levels.

Dr Palmer said there was some uncertainty around the impact on lake levels of localised thunderstorms. He urged everyone in low-lying areas to be prepared in case the rainfall is heavier than predicted.

The lakes are expected to be high from late today or early tomorrow and remain high for the rest of the week.

These lakes have a history of flooding, so taking steps now to ensure mitigation measures were ready was appropriate, Dr Palmer said.

The last time Lake Wakatipu caused some concern was in May 2010 when levels reached 311.48m above sea level and caused some localised flooding through the stormwater system.

The Clutha River downstream of Clyde is running high at around 1,000 cumecs and flows in the lower river are expected to remain high for several days. However, surface flooding is not expected.

ORC will continue to monitor the situation.

For more information go to http://water.orc.govt.nz, call the Flowphone on 0800 426 463 or you can receive flood alerts via Twitter. For more information, see the ORC Twitter Flood Alerts page at www.orc.govt.nz

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