Lake Hawea and the Neck in the backgbround, and Lake Wanaka in the foreground. Photo by Stephen Jaquiery.
A ''hypothetical'' plan that would reduce the risk of
Wanaka's town centre flooding and also generate enough
electricity for a town the size of Lake Hawea is being
floated by a University of Waikato PhD student.
Mohammed Majeed has been studying the potential in Central
Otago of using cheap off-peak electricity to pump water
uphill so it can be used later to generate electricity when
demand is high.
One of the two most promising possibilities he found was to
build a 5m-10m diameter tunnel between Lakes Wanaka and Hawea
at the Neck - the 2km-wide piece of land between the two
lakes on State Highway 6 to Makarora.
Mr Majeed's supervisor, earth and ocean sciences Associate
Prof Earl Bardsley, said yesterday the tunnel would be like
having another river, besides the Clutha River, flowing out
of Lake Wanaka.
Lake Wanaka is 65m lower than Lake Hawea and water going down
the tunnel into Lake Wanaka could drive turbines to produce
Water could also be pumped back up the tunnel into Lake Hawea
- at the rate of 100cumecs - when Wanaka's lake level was
The scheme's net power output was calculated to be 30MW. The
Clyde Dam, by comparison, produces 400MW.
Prof Bardsley said Lake Wanaka's natural high levels
coincided with high lake levels elsewhere and with low
''So it makes sense to reduce high lake levels in Lake Wanaka
by pumping into Lake Hawea with low-cost electricity.''
There was also the advantage that pumping would reduce Lake
Wanaka shoreline flooding.
''Mohammed's computer simulations indicate that the November
1999 foreshore flood in Wanaka township could have been
avoided if the scheme had been in place,'' Prof Bardsley
Lake Wanaka Guardians chairwoman Helen Tait said one of Lake
Wanaka's ''positives'' was that it was a natural lake, not
part of the hydro-electricity system.
''We would have serious concerns about anything that would
interfere with the natural status of Lake Wanaka.''
The Lake Wanaka Preservation Act was passed in 1973 to
maintain the lake's natural state.
Ms Tait said she did not consider any idea should be
dismissed ''out of hand'' and would be interested in its
likely effects being reviewed.
Wanaka identity Dr Dennis Pezaro said the idea had been
considered 40 years ago and dismissed as impracticable
because it required a ''base load'' of electricity that New
Zealand's system did not have.
Prof Bardsley has previously advocated a similar but much
larger scheme, to pump water 20km from the Roxburgh Dam to
Lake Onslow for hydro storage.
Mr Majeed presented the Neck scheme at the New Zealand
Hydrological Society conference earlier this month.
Queenstown Lakes Mayor Vanessa van Uden said it was difficult
to make an ''informed comment'' on the idea and a spokeswoman
for Contact Energy, which operates the Clyde and Roxburgh
Dams, said yesterday it had not been approached officially
and had ''no view''.