However since a large September protest, WCO angst has quietened.
Yesterday Twyford Irrigators Group spokesman Jerf Van Beek said they did not want to comment ahead of the first hearing, other than to say "we're comfortable with where it's heading".
Sally Gepp, lawyer for applicant Forest & Bird, said she felt there was now more understanding about what the WCO sought to achieve, and how it would interact with the Hawke's Bay Regional Council-led TANK project.
"It's been really good to see a bit more information and a bit more clarity get out there. We are looking forward to the hearing kicking off next week, we've got some evidence on native birds and native fish that is looking really good."
There will be about 115 presentations before the tribunal, with the hearing to end by December 11.
A vast range of parties will present their stance on the WCO, and evidence supporting this - including several local councils, Department of Conservation, Hawke's Bay primary sector representatives, local business owners, and recreational groups.
Three days will be taken up by presentations on behalf of the applicants.
This hearing will end with a site visit by the tribunal to locations of interest for the application.
The second stage of the hearing will consider the Ngaruroro's lower reaches, pencilled in for consideration in May next year when scientific information from TANK becomes available.
A large number of submitters on the application - including many from the horticulture sector - opposed the WCO on the lower part of the Ngaruroro but supported or were neutral on it for the upper reaches.
Of the application's 400 submissions, almost equal numbers supported it as opposed it.
However an extensive local campaign was led against the WCO, claiming it would decimate primary production in Hawke's Bay - including a protest which involved three simultaneous rallies, nearly a thousand people, and hundreds of tractors.
Vocal opposition came from the water-dependent primary sector, with fears a WCO would restrict water use, and remove the power to make decisions about how water was used from the community, and leaders. There was concern this could impact the local economy.
Many felt the planning process TANK is a better approach - this community-run water management project aims to protect water resources while balancing this with the needs of the community, and economy.
However the WCO applicants have maintained it could be good for the environment and economy, and assured it was not a threat to jobs.
Legislation states no WCO should affect or restrict any resource consent granted or any lawful use established in respect of the water body before the order was made.
Instead the WCO would recognise, sustain, and preserve outstanding values of the rivers.
Applicants have also noted it would give priority to conserving a water body's outstanding values for all time, rather than the smaller timeframe of the TANK remit.
There are 15 water conservation orders in New Zealand.