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A lake feeding the Clyde and Roxburgh dams is about to hit its minimum operating level as hydro storage throughout the South Island remains stubbornly low.
Lake Hawea, near Wanaka, could reach its minimum 338m level within days, prompting a warning by residents about the environmental cost if more water is taken.
Contact Energy operates the dams and can take another 2m of water, to 336m, if the tight power supply situation continues.
Guardians of Lake Hawea chairman Grant Fyfe said the area would suffer consequences for months or years from a lower lake, but the country as a whole isn't making any sacrifice.
"The Government refuses to acknowledge there is a crisis, so why sacrifice our environment if there is no crisis?"
Mr Fyfe said minimum operating levels were introduced in the 1970s when the lake fell to 327m, exposing river deltas and causing constant dust storms that carried as far as Ranfurly about 100km away.
Farmers found their wool quality affected, and exposed silt posed a danger similar to quicksand.
Energy Minister David Parker said the situation at Lake Hawea was a reminder that the environmental consequences of electricity production were borne mostly by people in small, distant communities.
Contact spokesman Jonathan Hill said the company had been in regular dialogue with the local community about the issue.
The level was likely to be drawn down to 338m over the next week and it was also expected to head towards the resource consent minimum of 336m during July.
"Hydro storage is still very tight. North Island thermal generation is running absolutely flat out and large volumes of electricity are being sent south."
Hydro storage is 56 per cent that of average, but power conservation measures during the past week have achieved savings of 3.6 per cent compared to the same period in 2007.
