Dredging of Kawarau Arm ruled out

WELLINGTON: Contact Energy is ruling out any major changes to its management of Lake Dunstan.

It comes in response to the announcement last week by the Otago Regional Council that parts of the electricity giant’s consent to operate Clyde Dam will be reviewed.

Every five years the council has a threemonth window to notify Contact Energy of its intent to review consent conditions.

But it is a rare, and potentially unprecedented, step to actually act on the ability.

The council notified Contact Energy on Tuesday, with just a day left in the threemonth window.

The council will review conditions relating to the impact of the dam’s operation on the Kawarau Arm of Lake Dunstan.

Lake Dunstan was formed at the confluence of the Clutha River and Kawarau River by the damming of the Clutha at Clyde.

Since it was filled in the early 1990s, the lake has provided recreational amenity to the community of Cromwell.

But the Kawarau Arm has in recent years become a shallow and at times smelly and dangerous mess, due to silt that used to wash down the Kawarau River and onwards along the Clutha River now being trapped and accumulating for three decades.

Last month, the council issued an abatement notice against Contact Energy over the Landscape and Visual Amenity Management Plan — basically the road map for how the Clyde Dam’s effects on the Kawarau Arm will be managed.

The council’s confirmation of a review followed pressure from community groups, who said Contact was not fulfilling its obligations as a corporate citizen.

Contact Energy said it welcomed the review and the opportunity to clarify the consent.

Its head of hydro generation, Boyd Brinsdon, said the root of much of the disagreement over the management of the Kawarau Arm was due to a lack of clarity.

‘‘I think part of our struggles — and I’ll call them that — over the last couple of years is a lack of clarity over what those conditions require and are meant to do. So having more clarity . . . as to what is required and what we do going forward is a good thing.’’

The Kawarau Arm was destined to become a braided river. It was about managing how that occurred and what management of the process looked like, Mr Brinsdon said.

‘‘It’s just a resolution about what can be added [to the consent conditions], consideration around native plantings, consideration of what other things we can do to improve and mitigate the transition from a lake to alluvial river environment,’’ he said.

He ruled out largerscale interventions, such as mechanical dredging of sediment in the Kawarau Arm, deeming it ‘‘completely impractical’’.

‘‘Our consents consider that and the hearings panel back in the 2000s acknowledged that. Their wording is very clear — the effects over the next 35 years, the terms of the consents through to 2042, will mean accumulation of sediment in the Kawarau Arm. The obligation on Contact, which isn’t clear, is to manage only the visual amenity values of that.’’

That will come as a blow to some members of the community who had been calling for dredging and removal of the sediment.

Otago Regional Council regulatory and communications general manager Richard Saunders said there was no timeframe for when the review would be completed. — RNZ