The Benmore dam spillway drew a large crowd yesterday, all
keen to see the spectacular sight of about 970cumecs of
water being released from the lake. The spill will continue
until noon today, then ease. Photo by David Bruce.
Spectacular spills from the Waitaki hydro dams yesterday
attracted large numbers of spectators as Meridian Energy
released almost 1000cumecs of water into the Waitaki River to
drop the level of over-full storage lakes.
Water was being spilled from the Benmore, Aviemore and
Waitaki dams.
Benmore proved the most spectacular, with two of its four
spillway gates open and the water hitting the concrete
footing and shooting high into the air.
The river was carrying about three times its mean flow at the
Waitaki dam.
Meridian has gone from worryingly low lake levels in
August-September in the controlled storage lakes of Pukaki
and Tekapo to coping with over-full lakes because of heavy
westerly rainfall.
With a further wet front expected on Thursday, it had to
release water to lower the lakes to provide a buffer to cope
with any further major inflows.
Since early January, the Waitaki River has been running high,
but the decision to spill even more water was made last week
after consultation with Environment Canterbury (ECan),
Central South Island Fish and Game Council and the Department
of Conservation - it was decided to release more water over a
24-hour period as a "flushing flow".
Yesterday morning, Meridian started boosting the river,
reaching a flow of about 970cumecs by midday.
That high flow is due to remain in place until about noon
today.
It is believed the flushing will benefit the river - for
example clearing didymo before the peak of the salmon angling
season and reopening the river's mouth in its normal place.
ECan senior engineering officer Bruce Scarlett said yesterday
a digger opened a new mouth for the river on Friday with the
aim of using the high flow to shift it back south.
Over the past few years, the mouth had shifted steadily north
until it was about 3km above the Glenavy huts on the north
side of the river.
Mr Scarlett said the new channel was "working well", with the
new mouth opening up and the old one to the north slowly
closing.
Central South Island Fish and Game officer Graeme Hughes said
the high flows and discoloured river would not initially help
anglers.
However, the new mouth would be easier to access and didymo
"should take a fair pounding", which would improve fishing
when lower flows resumed.
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