"The WCO will be detrimental to our economy and hundreds of jobs will be lost. We think we can achieve the environmental balance with the processes we have in place."
A rally is planned for September 19 where it's expected hundreds of Hawke's Bay residents will hit the road, alongside tractors and plenty of heavy machinery.
The rally is planned to start at the Hawke's Bay Showgrounds in Hastings and move through to Clive.
"We are also expecting crowds to come from Napier and Hastings with everyone congregating in Clive. Its important that Hawke's Bay stands up for Hawke's Bay because this WCO will impact our whole region," Mr Van Beek said.
Despite an existing consultative process called TANK that involves councils, growers, environmentalists, iwi and other groups, the New Zealand Fish and Game Council, along with four others lodged the WCO application with the Minister of the Environment.
Hawke's Bay Regional Council Chairman Rex Graham said he was disappointed outsiders had interfered with the TANK process, which had been underway for about four years.
"We have been working to achieve a balance between farming and the environment. But the WCO will decimate horticulture on the Heretaunga Plains,
"If the WCO goes ahead it will be the death of business in the region. Let's not under estimate this - we will be fighting it to the end."
All the water use linked to the Ngaruroro River WCO must be consented; including rural, urban and industrial takes. Roughly two thirds of actual water use is urban and industrial use and one third is irrigation.
According to the WCO application, the consented volume must drop from the current 55,475 litres per second to 1581 litres per second; a 97 per cent reduction.
The application also proposed to increase the minimum flow at Fernhill bridge, when restrictions on irrigation kick in, from 2400 litres per second to 4200 litres per second.
Mr Graham said under this plan there would be an average of 27 irrigation ban days, and in a dry year there could be up to 90 irrigation ban days.
That lack of confidence in water being available when needed was said to see growers deciding not to plant crops and processors being unable to secure supply to keep factories running.
"This is not just about the growers and farmers. It is about everyone in Hawke's Bay. We need to get everyone understanding that if the WCO goes ahead it will have devastating consequences," Mr Graham said.
Submissions closed on August 24 and a pre-hearing conference is set to be held on the September 15.