While acknowledging TANK had come a long way, Forest and Bird (one of the co-applicants) chief executive Kevin Hague said the first thing to remember was that when the application was made in 2015, TANK had been going on for some time and moving at a "glacial pace".
"The application was made when it did not look like TANK was going to be able to deliver on its mandate.
"As a participant in that process we acknowledge, particularly since [current Hawke's Bay Regional Council chief executive] James Palmer started, that the process has some legs but there is still no guarantee that it will produce an outcome that achieves what the WCO seeks to."
He said the critical point of legal difference was that a WCO gave priority to conserving the outstanding values of a water body for all time, which was not part of the TANK remit.
The TANK process took a compromise-based, multiple-use approach, the outcome of which lasted for only 10 years.
The hydrological science being generated to inform the TANK process, however, could also usefully inform the determination of conditions to protect lower river outstanding characteristics, and this was recognised by all parties, he said.
This week the special tribunal accepted a request to split the hearing into two stages - the first to consider issues relating to the upper reaches of the Ngaruroro, the second to consider the lower reaches, pencilled in for consideration in May next year when the TANK science information became available.
When the application was first proposed in 2009 there was no science available, and when it was prepared in 2015 it was accompanied by a draft order that contained some possible flow levels.
Some of these numbers had alarmed opponents, but were not part of the subsequent formal application, Mr Hague said.
"They are taking speculative numbers from that document and applying more recent science and saying if those numbers existed all sorts of terrible outcomes could be imagined.
"What they need to understand is that that draft order has no legal status."
He stressed that the applicants were not applying for a level of flow, they were applying for protections of values in terms of the supporting science, and that they were open to waiting until the regional council's science was available to inform that process.
In reacting to the WCO, opponents had raised fears that it would hinder the local economy and put jobs in jeopardy.
Mr Hague said it was important to preserve jobs and that the WCO was not a threat in this regard.
"When the application was filed a lot of the thinking behind it came out of local conversations in Hawke's Bay and the idea that having a river that was nationally valued in this way would become something of a marketing opportunity for Hawke's Bay.
"It could show that Hawke's Bay people take pride in their rivers and waterways and have an economy that works in harmony with the protection of nature and water."
Fish & Game was a co-applicant and its chief executive Bryce Johnson agreed the WCO could be good for both the environment and the economy, pointing to the fact under section 207 within Part 9 of the Resource Management Act the tribunal was obliged to have regard to the "needs of primary and secondary industry, and the community".
He also noted that section 199 of the act outlined the purpose of a WCO, which was to recognise and sustain any outstanding amenity or intrinsic values of waters in their natural state and the preservation as far as possible of any water body considered to be outstanding.
This included as a habitat for terrestrial or aquatic organisms, as a fishery, for its wild, scenic or other characteristics, for scientific and ecological values, and for recreational, historical, spiritual or cultural purposes.
The RMA, under section 217, provided that 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.
As such, Mr Johnson said the legislation provided controls to allay the substantive fears of opponents.
"It does not disturb existing resource consents - we are applying for a WCO with whatever resource consents are in place now".
"When those consents come up for renewal we will not have grounds to oppose that - our goal is to establish the nature and protection of river, including the fishery, with existing consents in place."
WhiteWater NZ, Jet Boating NZ and Ngati Hori ki Kohupatiki also supported the application and WhiteWater NZ's conservation officer Doug Rankin said that the upper Ngaruroro provided "two of the best multi-day whitewater rafting and kayaking trips in New Zealand".
Used by kayakers, rafters and white water adventurers both from the Hawke's Bay and nationally, it contained consistent Class II and III rapids, and a few higher Class IV rapids, making the river accessible and challenging to a wide range of white water kayakers, and especially intermediate kayakers, he said.
The river, on the Class II Oxbow section, was said to be an ideal nursery for developing paddlers from the Hawke's Bay Canoe Club (HBCC), school groups, youth groups and visitors to the region.
The braided section of the lower reach of the river between Whanawhana and Fernhill was also a popular area for jetboaters, and in the WCO application it was noted that almost 2500 jetboat passengers used that area each year due to the persistent and reliable shallow water jetboating opportunities it provided for people across the North Island.
As kaitiaki of Clive River Ngati Hori ki Kohupatiki were deeply spiritually and culturally connected to the Ngaruroro River and the lower reach, as well as the Clive River, was used for kai gathering and other uses, the application said.
