The government says the proposed Waimea Community Dam near Nelson would deliver major economic benefits through the potential to double annual profits from the catchment.
Primary Industries Minister Nathan Guy is in Nelson today to deliver a report on freshwater management on the Waimea Plains.
He said the report showed building the dam would secure the area's water supply and increase profits from $14.5 million annually, to nearer $30m.
The Tasman District Council allocated $25m in this year's long term plan to the expected $80m project, which has drawn criticism from other water users and rate payers.