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Further rains threaten water supply

NZ Newswire logoNZ Newswire 22/03/2017

Auckland's water shortage could become more acute if rains forecast for this weekend cause further sediment to run into treatment plants.

Run-off has already crippled Auckland's main Ardmore Water Treatment Plant after heavy rain and floods between March 7 and 12 clogged it with debris and reduced it to running at half its normal capacity.

Watercare chief executive Raveen Jaduram said new video showed mountain slips hundreds of metres long cutting swathes through native bush and forest plantations in the Hunua Ranges,

He said it didn't bode well if further rains fell this weekend.

"With large areas of exposed soil and water-laden earth, further rainfall ... elevates the risk of more silt washing into our water supply dams," he said.

It comes as Watercare said early indications were the unprecedented storm dumped up to two and a half times more rain on the Hunua Ranges than Cyclone Bola in 1988, which caused an estimated $90 million in damage.

Watercare subsequently became concerned it would run out of water and be forced to release untreated supplies that Auckland residents would need to boil.

To avoid this, it urged residents to each cut their water use by 20L per day.

However, Mr Jaduram said his staff had since worked hard to increase the water supply, over the past week increasing production from the Ardmore plant by 30 million litres a day.

"This is a real achievement by our water treatment team as the silt levels at the dams remain extremely high," he said.

"However, we are still producing significantly less water than normal, and with another rainfall event on its way, we're not intending to increase the output of our Ardmore plant further this week.

"This means the need for everyone to reduce their water use by 20 litres of water per day is still as important as ever."

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