An abandoned gold-miner's cottage in the Roxburgh Gorge,
beside Lake Roxburgh. Photo by Stephen Jaquiery.
Contact Energy called off plans to flush sediment from
Lake Roxburgh on Thursday, after expected high flows in the
Clutha River failed to eventuate. Heavy rain fell in the upper
Clutha catchment area on Tuesday and Wednesday and the power
company had hoped the river would rise enough to start the
flushing operation, for the first time in several years.
Contact generation manager Graham Quinn said Contact dropped
the level of Lake Roxburgh by 4m on Wednesday to prepare for
flushing.
"By lowering the level of the lake, it speeds up the velocity
of the water passing over it, and as it moves, it scours out
the sediment and moves it downstream."
As part of its consents issued in 2005 to continue operating
the Roxburgh and Clyde hydro dams, the company was required
to reduce the volume of sediment in Lake Roxburgh and in the
Manuherikia River to help mitigate the risk of flooding
during high flows.
The river was expected to rise to more than 1300cumecs
yesterday but the flow was closer to 850cumecs.
lynda.van.kempen@odt.co.nz
Bookmark/Search this post with:
A name, residential address, and (preferably residential) telephone number is required from readers who comment on ODT Online. These details will not be visible to site visitors.