Environmental groups did not get a chance to air their views at a weekend forum for Canterbury and Otago water users.
Agriculture Minister David Carter, who arranged the event, says they were deliberately left out - but their views won't be ignored.
Some 120 farmers and industry and irrigation scheme representatives from Canterbury and Otago attended the water infrastructure forum on Saturday.
Infrastructure and Finance minister Bill English, and Economic Development minister Gerry Brownlee also attended.
Mr Carter says 28 water schemes from North Canterbury to South Otago are in various stages of development, and a more co-ordinated approach to water supply is needed.
He says the forum needed to see what was possible for water supply and environmental groups were not invited.
Fish & Game chief executive Bryce Johnson says the decision not to invite environmental groups was loaded with "agricultural arrogance".
However, Mr Carter says no supply scheme will go ahead without environmental concerns being addressed.
Mr Carter says attendees were also worried that water supply projects won't be able to get off the ground without changes to the Resource Management Act.
He says the issue of water allocation won't be included in an initial review of the RMA, which will be in Parliament by February.
But he says there's every possibility that will be included in a second review, which will be passed into law before the next election.