He noted that new science was enabling growers to increase productivity within the same land area, and that a substantial amount of that growth was happening in Hawke's Bay.
Without certainty of water supply, however, investment in horticulture, potentially across the entire Heretaunga Plains, would stop, he said.
"I urge the tribunal to recognise that horticulture is a natural outstanding attribute ... horticulture has been here for generations, it's a fundamental part of the social and cultural framework of the region."
Like other submitters New Zealand Apples & Pears raised concerns that the WCO application was an attempt to usurp the current TANK (Tutaekuri, Ahuriri, Ngaruroro, Karamu) Hawke's Bay Regional Council (HBRC)-led plan change process.
This issue was raised with regional council chief executive James Palmer who also appeared before the tribunal yesterday.
The regional council had opposed the WCO in both the lower and upper reaches of the Ngaruroro River, and Mr Palmer said a key element of that opposition was that it interrupted the consultative TANK process.
When asked why the HBRC had taken such a strong stance on TANK, when other submitters had suggested the WCO could work in parallel with that plan change, Mr Palmer said the key factor was that the WCO did not take into account community views.
"This process is one in which the community is not making decisions about the management of the resource.
"We consider the idea that resources should be managed at the most local of levels is a very important underpinning of the RMA.
"We have had a chequered past as a council in the extent to which we have worked with the community - we are moving fundamentally as an institution to work in partnership with communities.
"We run the risk of decisions being taken away from the community in some parameters and it's for that reason that we favour the TANK collaborative process."
He acknowledged there was a reasonable chance if a WCO was granted that the provisions would work in with any TANK plan change rules, but added that it was not so much the product that was of concern to the council, it was the journey to get there.
Mr Palmer said the scientific information gathered through TANK around river flows would be available to the tribunal in April or May next year.
The hearings had been split into two stages, the first considering matters to do with the upper Ngaruroro River, which was due to continue until January next year.
Stage 2 of the hearing would be for the lower reaches of the Ngaruroro and Clive Rivers, and was likely to begin in May next year or when the scientific information was available.
