Opening the spillway

The lake levels are too high in the Waitaki hydro lakes so Meridian Energy has opened the spillway in Benmore dam:

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More water from the Benmore dam fills Lake Aviemore so the spillway in the Aviemore dam is also open and that in turn puts more water into Lake Waitaki so the  the Waitaki dam is now overflowing:

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The Waitaki River is now flowing at 950 cubic metres a second. We might want to remember that next time there’s a power crisis.

However, the high flow is welcome because the flood will clean up a lot of the didymo (also known as rock snot) which is thought to have been brought into New Zealand is fishing waders and now infects many of our rivers.

The high flow will also move a bank which has developed at the river mouth.

10 Responses to Opening the spillway

  1. rayinnz says:

    We went over the lower bridge last night, the traffic were all just crawling along checking out the Waitaki running bank to bank………a “banker” they used to call floods in the old days
    Mind you last time there was a real flood it was carrying almost three times as much water……awsome

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  2. Julie Fairey says:

    Wow, that’s pretty impressive!

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  3. pdm says:

    Call me simple but wouldn’t it make sense to have diverted the surplus water into storage lakes as back up in case of low flows in winter? Or is that not practical.?

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  4. Tim Selwyn says:

    A spectacular event. Good photos.

    It’s not to clean out didymo, seriously. That can’t be right. How much of the material will be washed downstream, how much will remain? I can’t see it having any impact at all – apart from spreading it. Where did this didymo claim originate?

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  5. homepaddock says:

    pdm – these are the storeage lakes and they’re full.

    Tim – people from Fish & Game and the Canterbury Regional Council both mentioned the didymo clean-out in news reports though to clarify neither said it would get rid of it completely, just flush a lot of it out to sea.

    I read your post disputing this: http://tumeke.blogspot.com/2009/01/didymo-infestation-herald-thinks-water.html

    The ODT: http://www.odt.co.nz/the-regions/north-otago/40035/crowds-turn-out-see-dam-spills quotes a Fish & Game officer saying didymo would”take a fair pounding”.

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  6. My daily water use in eight seconds!

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  7. Rissoles says:

    pdm – As homepaddock replied, these are the storage lakes.

    There are two main reason they need to spill water.

    1 – Environmental. The lakes within the scheme are required to stay between the upper and lower limits set by authorities and the power stations are optimised to run at these levels. Outside these limits environmental impacts are considered adverse – bank erosion, lake side plant health (too much/not enough water), fish health, aesthetic value etc. etc.

    2 – The electricity system in NZ -If Meridian don’t sell all their power on the market when the lakes are full they are forced to ‘pour their power down the river’ as they cant keep it (I don’t think this happens very often at all).

    I believe penalties apply if the lakes fall out of the operating limits, so obviously Meridian felt that the lake recharge (snow melt & rainfall) was sufficient to maintain high levels when power is needed most in winter.

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  8. […] I didn’t have a camera with me so took these photos on my phone. Better quality shots from when the spillway was opened in Janaury are here. […]

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  9. kay says:

    Fantastic photo’s – Am about to plan a visit to benmore this decemeber / Jan (2009). – I was born in otemata – (currently living in australia).

    My father was one of the many that was part of the building of the Benmore dam way back in the 1950’s.(sadly he died when I was six years old.

    I have some great photos of them all at work – when there was No dam to start with. If anybody is interested let me know would be happy to forward on photos.

    Would really appreciate any information from past workers on the dam if any of you guys know how to trace any of them – please let me know.

    cheers
    Kay

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