Drought may force closure of irrigation scheme

17:14, Feb 26 2013
Tim Laverack
Big dry: Tim Laverack checks an irrigation valve at Lone Gum Vineyard which he manages ahead of the scheme that waters the vines being shut down this week

The Marlborough District Council will shut down the Southern Valleys Irrigation Scheme on Thursday or Friday, unless rain falls this week.

Council hydrologist Val Wadsworth said yesterday the scheme fed water from the Wairau River to about 4500ha of mostly vineyard land. Supply would be cut to affected properties in the Benmorven, Fairhall River and Hawkesbury areas as well as Guernsey Rd and Fareham Lane, once flow in the Wairau fell below 8 cubic metres per second (m3/s).

People pumping class B water from the Wairau River west of Renwick must also stop irrigating if flow fell below the trigger point, Mr Wadsworth said. That could affect up to 50 takes covering 5000ha of irrigated pastoral, cropping and dairy farms as well as vineyards.

Flow was falling steadily, on Sunday averaging 11.5 m3/s, he said. People with Class B water takes from the Waihopai and Awatere Rivers might also have to stop irrigating in one or two weeks.

"We are not seeing anything that looks like rain for a fortnight at least," he said.

Mr Wadsworth expected Southern Valleys growers to pump from wells and storage dams, if available.


Groundwater levels had recovered well in the past few years, he said. Spy Valley Wines general manager Blair Gibbs said the Southern Valleys scheme watered 50ha of the company's 200ha of Marlborough vineyards.

If the scheme shut down the company would tap wells on the property, Mr Gibbs said.

"We are a long way off any serious problems."

In the past the scheme had been shut down for two or three days then rain fell, he said.

This season, the fine weather looked likely to last.

Chris Simmonds, who grows 40ha of grapes in Brookby and Dog Point roads, was not worried about the shutdown yesterday, despite having no back-up supply for one vineyard. A member of the scheme's establishment committee, he said records showed the Wairau River flow had never stayed below 8m3/s for more than 10 days and the end of the season was close.

Developers considered building a storage dam into the Southern Valleys scheme but rejected the idea because of the cost to the community, he said.

Nautilus viticulturist Mike Collins said yesterday the company could irrigate pinot noir grapes in its 5ha Clay Hills vineyard in the southern valleys using water drawn from a large dam.

That held enough water to irrigate the vines for about four weeks at a low rate. Ideally, the block would be watered until about a month after harvest when leaves started to fall, he said.

Pinot noir ripened earlier than sauvignon blanc which "will be a bit of a help".

Shutdowns during dry periods were part of the deal with the Southern Valleys scheme, which was why Nautilus built the dam as an insurance, he said.

The Marlborough Express