"We want to determine how we manage our environment and our resources," he said.
"The whole community has got together and said 'Hawke's Bay for Hawke's Bay'. We don't want to be bullied by Wellington-based NGOs coming here to tell us what to do when we have an existing consultative process under way."
Eleven speakers have been lined up to give speeches at Farndon Park, including Ngati Kahungunu Iwi chairman Ngahiwi Tomoana, Bruce McKay of Heinz, Federated Farmers president Katie Milne, local government figures, and political candidates.
One of the speakers, Hawke's Bay Regional Council chairman Rex Graham hoped lots of Hawke's Bay residents would come out and show their support for the TANK process, a water management process being led by the council.
People also need to advocate for "local decisions to be made locally", he said. If decisions about the environment could not be made at a local level, this would be a "dreadful breach" of mana whenua (territorial rights), and the rights of regional residents.
There has been widespread concern about the potential impacts of the WCO if granted - particularly about restrictions it could impose on new water takes, and the preference for the TANK process.
Responding to the rallies, applicant Whitewater NZ president Nigel Parry said that people would form their own views, but their members' and supporters' interests lay in the upper Ngaruroro.
"It is an outstanding section of wild river set in a magnificent environment and a worthy candidate for a Water Conservation Order, the equivalent of a National Park status for rivers."
Applicant Fish and Game chief executive Bryce Johnson welcomed comments last week from the chairman of the Special Tribunal hearing the application, "regarding the ineffectiveness of protest rallies on the tribunal and its deliberations".
He added WCO applicants were engaging with submitters to ensure the best information was accessible to the tribunal to support its deliberations.
"We anticipate this information will include the science being developed for the HBRC's TANK process, which will assist the determination of any conditions and rules, particularly for outstanding characteristics identified in relation to the lower river."