The Manuherikia Catchment Water Strategy Group has developed new figures for the plan after it last year deemed price estimates in a feasibility study too high.
It is considering low, medium and high options for a dam which would be the basis of a widespread irrigation scheme in the Manuherikia and Ida Valleys.
The low option would involve raising the height of Falls Dam, whereas the medium and high options would require a new dam to be built at the same site.
The new estimate for the high option is $80million, down from a previous estimate of $146million, due to a design change to create a rock-filled concrete dam instead of one made from solid concrete.
The cost of the distribution system remains about $100million.
In about a month's time the group will send information packets to potential irrigators with a declaration of interest form to determine how many would use the scheme and how much water each would use.
The amount of interest would determine which dam option the group would take.
Group chairman Allan Kane said it was hard to know what the interest would be "but there has been substantial re-investment in irrigation in the valley."
"I believe the new prices are more viable.''
He was confident the plan would go ahead in some form.
Initially the group considered building two dams in the Ida Valley to increase irrigation in the area.
While "not off the table'', that option was not being pursued by the group as it did not seem economical, he said.
It developed some alternatives, with the most likely being building a water race from Falls Dam to the Poolburn Gorge.
The water group was created in 2011 to represent the interests of six irrigation companies, private irrigators and community interest groups in the Manuherikia and Ida Valleys.
