The site of the proposed Ruataniwha Dam near the Makaroro River. Photo / File

Federated Farmers is fighting back against claims the Ruataniwha dam will be bad for the environment.

The Hawke's Bay Regional Council voted seven to two, to put $80 million into the Ruataniwha Water Storage Scheme, as long as an investor is found.

Greenpeace says the dam will be disastrous to the environment.

SEE ALSO: Protests to prevent ratepayers' money funding the Ruataniwha dam

But Regional Federated Farmers President Will Foley said the original reason for the Ruataniwha dam was to relieve low water levels in the main catchment zone of the Tukituki River.

Mr Foley said biodiversity there has been threatened since the 2007, 2008 and 2009 draughts, and the dam would help correct that.

He said it's a couple years late but they're in the grips of another drought and farmers need the irrigation to get through the dry periods, and increase their productivity.

Mr Foley added that of the 196 farmers who've signed onto the scheme, only one is a new dairy farm; the rest were already there so it shouldn't have a negative impact on the environment.

But Greenpeace Agriculture campaigner Genevieve Toop said the scientific evidence doesn't agree. She said the rise in farm production the dam allows will be enough to pollute more waterways.

Ms Toop said the message is simple: if we want clean rivers we need fewer cows, to have fewer cows we need to stop building large irrigation schemes that create more industrial dairy farming.

She added it would be a terrible misuse of public money because not only would the 80 million be from tax payer money, but the clean up will be too.

Will Foley said it's likely an investor will be found within weeks.