Stephen Grundy, of Omarama, inspects the new Waitaki River
mouth, which was opened by a digger last Friday, and
enlarged by the 950cumecs flushing flow over the 48 hours
until noon yesterday. The mouth, over the past few years,
had moved about 3.5km north, fed by the channel at centre
left. Photo by Ruth Grundy.
The Waitaki river started falling at noon yesterday,
after 48 hours of a 950cumecs flushing flow that was released
by Meridian Energy.
The release, originally planned for 24 hours, swelled the
river from 6am on Monday, reaching its maximum at midday
Monday.
On Tuesday, it was supposed to fall from midday but, after
consultation with Environment Canterbury (ECan), it was
decided to keep it going for a further 24 hours to maximise
the benefits to the river.
Those include flushing the river of didymo, and consolidating
a new river mouth at the end of the main stream, instead of
about 3.5km further north, where it had shifted over the past
three years.
The release was to ease pressure on storage in Lakes Pukaki
and Tekapo, which were over-full.
Meridian needs to maintain a buffer in the two lakes so it
can cope with any heavy rain in the catchment.
Meridian's external relations manager Claire Shaw said
yesterday the river started falling from midday and at about
5pm was at 750cumecs.
It has to be lowered according to conditions in Meridian's
resource consents to operate the Waitaki hydro generation
system.
Today, the flow was expected to reach 450 to 500cumecs, where
it could be held for a few days.
However, that would depend on in-flows into the storage
lakes, and the extent of a heavy rain warning for southwest
New Zealand until Sunday.
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