Detailed design work has begun for a $375 million irrigation scheme for the Canterbury Plains.
Supporters of the Central Plains Water irrigation scheme have spent 10 years planning and negotiating consents to take water from the Rakaia and Waimakariri rivers.
Central Plains Water chief executive Derek Crombie said it will be built over about four years and farmers will have to pay about $500-a-hectare per year to fund it. He acknowledged it won't be cost-effective for everyone.
The pipes and canals will irrigate 60,000 hectares between the Waimakariri and Rakaia rivers; more than double what is now irrigated by wells.
Construction is expected to begin in early 2014.