The mayors of Napier and Hastings have requested that the Hawkes Bay Regional Council produce an independent economic analysis of the proposed Ruataniwha water storage scheme.
The regional council and its investment company have made applications to the Environmental Protection Authority on the project, which would supply water to about 25,000 hectares of land from a dam on a tributary of the Tukituki River.
Hastings mayor Lawrence Yule says the regional council is proposing to invest tens of millions of dollars of ratepayers money in the dam.
He says both he and his Napier counterpart Barbara Arnott want to make sure the project does not place regional ratepayers at risk.
"We want to make sure there is some independent thought and reporting given to the commercial realities around the dam, particularly around the ratepayers' interests."
He says the regional council, which is driving the project, is considering investing up to $80 million of ratepayers money - the largest single investment ever in Hawke's Bay.
Mayor backs scheme
However the mayor of the Central Hawke's Bay District says it's time to hit the go button on the scheme, which he says will bring tremendous economic benefits.
Peter Butler says 200 - 300 farms are likely to benefit directly, and there will be gains for the wider community and the environment.
Mr Butler says water from winter will be stored and then released.
"This dam is going to be nearly 100 metres tall, the wall of the dam and go back seven or eight kilometres - there's a massive amount of water there - and at periods during the summer they're going to release extra water to flush the river - so there's good for the greenies as well."
Mr Butler believes the scheme will be the making of Central Hawke's Bay, and says his council is fully behind it.