Various options for using water from the Mackenzie lake have been examined in the past, but came to a head in 2004 when the Aoraki Water Trust took Meridian Energy to the High Court to challenge the electricity company's right to water.
The court ruled Meridian had the right to all the water in Lake Tekapo and no-one else could use it without the company's permission.
This year, Environment Canterbury (ECan), which controls access to water in the Mackenzie district, commissioned a study on transferring water for environmental and irrigation use from Lake Tekapo to South Canterbury, through Burkes Pass. It was part of a wider consideration of water options for South Canterbury, ECan commissioner David Caygill said yesterday.
More than 100 years of previous work were studied to answer existing water quality, environmental and cultural challenges.
Two options were looked at using two different amounts of water from Lake Tekapo, but neither appeared to be economically viable.
Option one, costing between $264 million and $382 million, was using 2cumecs of water all-year round which would irrigate 11,550ha; option two, costing between $478 million and $691 million, 10cumecs on a seasonal basis which would irrigate 25,000ha.
Taking into account construction, operational and on-farm costs, option one for a dairy farm would result in an estimated loss of $2430 per hectare.
The same dairy farm would have an estimated loss of $1857 per hectare under option two.
The economic analysis in the report also allows for the lost generation from the existing Waitaki hydro-electric scheme, any potential generation from the transfer scheme, as well as the benefit from additional or more reliable irrigation in the South Canterbury region.
However, the study would provide water management zone committees with the information needed to make comparisons between the Tekapo concepts and other ideas and proposals for bringing water into the relatively water-short South Canterbury region.
''While the report shows neither of the Tekapo transfer concepts appear to be economically viable, it provides a comprehensive suite of information useful as a resource to inform further work and ongoing discussions,'' Mr Caygill said.
