Effect on whio not yet known, says F&B

Boom across the Makotuku Stream at Horopito which had diesel leaked into it from Ruapehu Alpine Lifts Turoa ski field.

It is too early to know if the endangered whio (blue duck) will be affected by the diesel spill into the Makotuku Stream but any reduction of their food supply is a significant issue, Forest & Bird says.

North Island conservation manager Mark Bellingham says the whio are going into their breeding season and supplies of caddis, damsel and stone flies are essential for egg production and then feeding the ducklings.

The 15,000 litres spilt from the Turoa ski field has gone into prime whio habitat.

"Any repercussion for the birds won't be known until the water is tested by DoC or Horizons and we can see how much diesel is still around," he says.

"It's one of those things that depends on a number of issues. If we have rain for instance that will help flush it down the river."

Mr Bellingham said he was surprised there was no set-up such as a bund at Turoa to contain diesel from the tanks.

"I wonder why they didn't have some kind of concrete platform?"

Fish & Game say staff are investigating the impact of the diesel spill and are advising anglers to avoid fishing the Makotuku Stream for now.

Fish & Game Taranaki says there have been no reports of any fish kills so far, but until further inspections have been carried out, this can't be ruled out.

Fish & Game officer Allen Stancliff said it appeared that by the time the authorities were notified days after the event, most of the spill had already been flushed down the stream.

"There have been a couple of minor freshes which would have assisted the flushing process.

"Makotuku Stream is a tributary of the Mangawhero River and an important spawning and juvenile rearing area for brown trout that run up from the Mangawhero to spawn. "So in our view, it contributes to maintaining the regionally significant Mangawhero River trout fishery."

Mr Stancliff says the Makotuku is a minor trout fishery but, fortunately, given what has occurred, doesn't receive a lot of use by anglers.

"We advise anglers to steer clear of the Makotuku until the all-clear is given and, of course, avoid eating any fish caught in this waterway as a precaution."