A proposed multimillion-dollar widespread irrigation scheme in the Manuherikia and Ida Valleys could be hindered if the Otago Regional Council sets minimum river flows too high.
Manuherikia Catchment Water Strategy Group chairman Allan Kane updated the Central Otago District Council about plans for the scheme at a meeting in Alexandra yesterday.
Potential irrigators have until October 25 to register their interest.
They would put up $50 per hectare they wanted irrigated to fund the next stage of the project.
The Otago Regional Council is in the early stages of setting minimum flows in the Manuherikia River.
Mr Kane said the plans were based on a minimum flow of 1200 litres per second.
''There would be a significant additional cost to irrigators if it was set much higher than that.
''We had hoped that regional council, who are involved in our group, may have just accepted the consultation and assumptions that we have been doing towards this and been able to put that into effect. But they are very strong on the fact that they are doing their own procedures.''
Cr Clair Higginson questioned whether biodiversities in the river would be preserved.
Mr Kane said as much of the land was already irrigated, he did not think there would be many areas where indigenous species would be effected.
The group thought it was important to preserve wildlife which was already there, he said.
He had ''no idea'' at this stage what the interest would be, he said.
''But existing irrigators within the Manuherikia understand that something has got to be done and I think the private water rights people do, too.''
Depending on the interest the scheme would involve either raising the Falls Dam by 6m, or building a new dam, 15m or 20m higher, directly downstream.
It would be ''beneficial to everyone'' build a new dam, he said.
''If we're trying to raise and upgrade that one, it almost means most of the season will be dry and that's totally unacceptable for most of the farmers.''
Estimated costs for dam construction work range from $28million to $80million and the estimated cost of the largest distribution option is $100million.
It would probably take three years to get to the point were construction could begin and a further two to build it, Mr Kane said.
