The Kurow Duntroon Irrigation Company is undertaking a $45 million expansion and modernisation.
Its coverage will increase from 1983ha to a potential 5500ha and some 44km of open canal will be replaced with 37km of underground pipes.
The water will be taken from Lake Waitaki rather than from tributaries of the Waitaki River.
That was an environmental gain for the creeks, company chairman Geoff Keeling said.
Improved irrigation efficiency meant no more water would be used despite the larger area to be covered.
The scheme, one of the last to receive funding from Crown Irrigation Investments Ltd before it withdrew from large-scale irrigation developments, was designed and being constructed by Monadelphous New Zealand.
It began in January.
Project manager Marcus Brown said there were 15 staff in the office and up to 40 on the ground.
They included five pipe-laying crews. One was working from the Waitaki dam towards Kurow, one from the Kurow Racecourse towards the dam, and the others ''at the back of the scheme, on the laterals''.
He hoped all pipes would be installed by mid-November and water would be flowing in February.
''They're making good progress and making the most of all the good weather,'' Mr Brown said.
''The acid test will be in September when we do the link between the dam and Kurow.''
The scheme would have ''very positive'' outcomes for local landowners and the wider community and economy, he said.
From day one it would supply 4200ha, so there was already significant commitment and room for more.
''Fingers crossed - it's an intensive project. There's a lot happening.
''We're cautiously optimistic.''
