There is also angst from the protesters that the WCO "rides roughshod" over the community-led water management process TANK, and growing unease at decisions about the region being made outside it.
"The people of Hawke's Bay, we feel we are actually hamstrung by the WCO application," organiser, grower, and pitchfork-toting Jerf Van Beek told the crowd.
"But we actually have got a voice, we've got that here today, the whole nation is watching us and what we're doing here".
Placards reading "Let the TANK roll on", and "our rivers our decision" were hoisted as speakers discussed the impact of the WCO - from a young orchard worker worried about her career, Ngati Kahungunu Iwi Inc chairman Ngahiwi Tomoana, and political candidates.
"This application, if accepted in its current form, will decimate primary production in Hawke's Bay. Its proposed prohibitions and restrictions that will severely restrict the ability of all water users to continue to function as they do today," said Bruce McKay of Heinz Watties.
He compared the change to the restrictions to "dropping the speed limit on the open road from 100km/h to 3km/h".
"Actual extraction is less than the consented volume, but its easy to see there's nothing left for growers or industry once the supplies for people and basic infrastructure are deducted."
"Without those crops, or fruit, or grapes, there is no industry. Hastings will no longer be the fruit bowl of New Zealand, but the dustbowl of New Zealand, while all the water that currently makes us prosper flows out to sea."
The horticulture sector had a big presence at the rally, but mingled with farmers, winegrowers and urban residents. This united front was more stark given recent divides in Hawke's Bay - as mentioned by Federated Farmers provincial president Will Foley.
"There's been too much division for too long now. One of the benefits I see out of this is unity."
"Technology, innovation, and the Kiwi number eight wire attitude, with locals in charge of local matters, is how we need to move forward. Let's stop wasting time and money on special hearings, court cases, and lawyers, and get our Hawke's Bay community back around the table, working out what's best for Hawke's Bay".
Fears on the WCO's urban impact were expressed by regional council chair Rex Graham, Hastings mayor Sandra Hazelhurst, and Napier mayor Bill Dalton.
Mr Dalton said his community would stand with Hastings.
While his primary sector knowledge might be lacking, "what I do know is that every so often Wellington rises up on its hind legs, and tries to impose an unreasonable condition on Hawke's Bay, when those decisions are much better made by the people of Hawke's Bay".
"We need to tell them to go and get stuffed. We need to tell the people in Wellington that Hawke's Bay people are quite willing and able to make the right decisions for Hawke's Bay people."
Mr Graham defended TANK's progress, saying such processes were slow because they had to involve input from the entire community. This needed to be defended, so communities could make decisions about their own area.
"[The applicants] have bought a fight, and they're going to get it from this community."
Parked at the protest were nearly 400 tractors which made the journey from Hawke's Bay Showgrounds yesterday.
Bostock orchard hand Robert Hunter said he felt the applicants needed to realise how things worked in Hawke's Bay.
"And how people rely on it, because if they don't get the water then there's no work, no apples, nothing."
Among the 20 or so people who walked from Waitangi Estuary were concerned Havelock North residents Peter and Margaret Watt.
"I'm really ticked off that someone from out of the region thinks they can tell us what to do with our water," Mr Watt said.
Mrs Watt said she thought the TANK process was a much better way to protect the waterways.
The majority of those gathered yesterday opposed the WCO, but many in Hawke's Bay support it, or support it with changes.
This is shown in the nearly 400 submissions received on the application, with almost the same amount supporting the WCO as opposing it.
Those in support believe the WCO will preserve the rivers, and their wildlife, and ensure the rivers can be used for recreation. Others say it would protect the waterways as a taonga.
A number of horticulture industries oppose the WCO on the lower reaches of the Ngaruroro, but support it on the upper part.
