He said his information was sourced from Niwa, "not from crazy greenies".
The farming sector, he said, needed to stop attacking "good science".
Fellow panelist, Central Hawke's Bay farmer Hugh Ritchie, said the Bay was poised to face some "tough decisions", and backed water storage as one option. "There are issues with certain catchments and some farming systems need to evolve," Mr Ritchie said.
Yet rather than targeting all dairy, cropping or stock farmers, he said authorities should concentrate on anyone who breached their water take.
Local blogger and publisher, Tom Belford, one of the forum's five panelists, said Hawke's Bay Regional Council was poised to deliver policy that would dictate "how the region manages water for years to come".
"2012 is going to be a watershed year for water policy in this region," Mr Belford said. "It will effect how the region manages water for decades to come."
Council had historically favoured the region's economic wellbeing over the environment, he said. "Their stance seems to be how much can we afford the environment to interfere with productivity. This needs to be turned on its head."
Other panelists were iwi adviser Morry Black and Hawke's Bay Regional Council chief scientist Graham Sevicke-Jones.
The panelists answered many questions from the audience. Fisherman John Scott applauded the presence of the sole regional councillor Liz Remerswaal but criticised the absence of her fellow councillors.
"They're the key thing that's missing from tonight's forum - they're the policy makers."
Election candidates for Hawke's Bay electorates also addressed the forum.