A huge diesel spill at Turoa ski field has contaminated Raetihi town water supply 20 kilometres away, forcing its closure.

It could take more than 10 days for the water to become decontaminated.

Fresh water is available from a tanker in the town, and the council said the sewerage system was still operational.

Up to 15,000 litres of diesel, from a tank at the Ruapehu Alpine Lifts (RAL) ski field base, leached into the Makotuku stream - the primary tributary to the Raetihi town water supply.

Ruapehu District Council deputy mayor Don Cameron said the spill appeared to have happened some time on Sunday, but how it happened was unknown at this stage.

‘‘There was a smell coming from the water,’’ he told Radio New Zealand.

It was originally assumed to be a bacterial contamination after heavy rain, "but it was apparent by Sunday evening that that was definitely not the case and it was definitely a hydrocarbon of some kind.’’

Two people were reportedly ill after drinking the water, but there had been no confirmed cases of illness, he said.

The council was dealing with it as ‘‘a serious public problem’’, he said.

’’We do know the stream is slowly clearing but it is not yet clean enough to flush out pipes and flush out the reservoir.’’

Residents reported a ‘‘stinky, stenching’’ smell and one said the water tasted like ‘‘diesel’’.

A daycare centre and some businesses in the town closed yesterday.

Authorities said the Raetihi reticulated water supply system could take more than 10 days to be decontaminated, though the Ruapehu District Council initially signalled that the supply would initially be shutdown for up to 36 hours.

RAL chief executive Dave Mazey said the company was not yet clear about how the spill happened, but confirmed it was ‘‘significant’’.

‘‘It appears there is a strong linkage between the spill and the contamination and we are working through the appropriate authorities as fast as possible to firstly, identify the cause, and secondly, resolve and address it,’’ he said.

Mazey said the spill happened at part of the base area on the southern slopes of the Turoa ski field where the tank was sited. The diesel leached into a water catchment areas and into the upper headwaters of the Makotuku.

‘‘We will be working closely with Horizons [Council] and DOC to understand what the impact is,’’ he said.

Ngati Rangi chief executive Che Wilson described the spill as ‘‘devastating’’, both for the communities it affected and the environment, which is a world heritage site.

The impact on native flora and fauna was unlikely to be known for several days while Department of Conservation teams surveyed the area, including any impact on whio, a blue duck classified as a national vulnerable species.

Maungarongo Marae, in Burns Street, Ohakune, and the local rugby club are allowing Raetihi residents to use their showers at set times.



