Wary eye on lake levels as heavy rain predicted

All four spillways were open yesterday  on the Clyde Dam and holiday-makers (from left) Catherine...
All four spillways were open yesterday on the Clyde Dam and holiday-makers (from left) Catherine (8), William (5) and Isabella (9) Sole, of Auckland, enjoyed the spray shower. Photo by Lynda van Kempen.
The Lake Wanaka wharf disappears beneath the waves. Photo by Mark Price.
The Lake Wanaka wharf disappears beneath the waves. Photo by Mark Price.

Predicted heavy rain from tomorrow is raising concerns about possible flooding of Lakes Wakatipu and Wanaka.

Both lakes are already about a metre above normal levels because of heavy rain at New Year.

While levels are dropping, Queenstown Lakes District Council emergency management officer Jon Mitchell says more heavy or prolonged rain could create problems for low-lying properties.

The level of Lake Wakatipu yesterday was 310.5m above sea level and is considered high at 310.8, when it reaches the top of beaches.

Flooding can occur in Queenstown at 311.3m but the serious flooding in Queenstown in 1999 occurred when the level was 312.8m.

Lake Wanaka was at 278.3m yesterday. Flooding starts at 280m.

Mr Mitchell said, it was ''business as usual''. The council would not take action ''unless the situation looks likely to be changing for the worse''.

Any flood warnings would be issued by the Otago Regional Council.

The district council would then call together emergency services and others to ensure everyone was working as a team.

''At the moment the forecast is only for possible heavy rain.

''We would wait and see what is being delivered, but it is certainly better to be ahead of the game rather than wait until there's water in the streets.''

Businesses in low-lying areas have plans to remove stock and equipment if necessary and sandbags would be provided by the council in some circumstances.

''As it gets higher the water tends to come in through drains so sandbags are only useful for a low-level event.''

Mr Mitchell said the problem of higher lake levels could be compounded by wind creating waves and washing debris ashore.

Southerlies or southwesterlies affected Queenstown and westerlies affected Wanaka.

Mr Mitchell said the heavy rain was predicted to fall for a short time but if it lasted longer or was more intense ''then there could be some issues''.

MetService spokesman Ramon Oosterkamp said an active front would move on to the South Island tomorrow, bringing heavy rain in the west, as well as gale or severe gale northwest winds in the east.

''The western and alpine areas of the South Island may see another period of heavy rain, which may pose problems to those areas affected by the wet weather of last week,'' he said.

Contact Energy hydro generation manager Graham Quinn said the Clutha river flow was roughly twice the average for this time of year and while the level was relatively high, sediment was being ''flushed'' from Lake Roxburgh, moving it further downstream to alleviate the risk of flooding in Alexandra. The flushing operation began on Friday and would continue while flows were high. If the predicted rain upstream eventuated, the dam would be forced to spill anyway, he said, as there was not much head room in the lakes behind Contact's dams.

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