Moves afoot to change river's direction
Parts of the flood-prone Upukerora River could be restored to their pre-2009 channel shape to help protect Te Anau and its two sewage ponds from flooding.
In June, The Southland Times reported the Upukerora River threatened to swamp parts of Te Anau and its two sewage ponds because it was overflowing and diverting down alternative channels.
Environment Southland catchment works supervisor Ken McGraw said yesterday the regional council was currently working on a design to reposition parts of the channel from the Milford Rd bridge to downstream of the Te Anau sewage ponds.
The design included moving parts of the river to its pre-2009 flood event channel, installing rock work to maintain the channel, and moving a further 30,000 cubic metres of river bed gravel and sediment.
The proposed design comes after a survey on the Queen's Birthday Weekend flood event showed a loss of capacity in the channel, which needed to be addressed, Mr McGraw said.
There was no risk to the sewage ponds at this stage but the regional council did not want another flood event to threaten the ponds.
When complete, the design will be presented to the Southland District Council engineers and the Te Anau Community Board to decide if it will go ahead.
Mr McGraw said he would know the cost and who would pay for the works in about two weeks.
Emergency work conducted on the Upukerora River in June cost Environment Southland ratepayers in the Te Anau Basin rating district $60,000 after the cost had earlier been estimated at $40,000.
It involved removing about 40,000 cubic metres of material, building a flood defence bank on sections of the river and creating a new diversion channel.
There was not enough time for an in-depth costing or surveys, the focus was on getting the job done to avoid further breakouts, he said.
Gravel and debris ran downstream, built up in the middle of the river and caused it to divert down alternative channels.
Environment Southland catchment manager Noel Hinton told The Southland Times in June that future maintenance costs could also fall on ratepayers if there was no demand for the river's gravel by the construction industry.
- © Fairfax NZ News
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