Te Arawa Lakes Trust is opposing plans to discharge treated wastewater into Lake Rotorua in what is being described as a "surprise" move at a late stage.
It's a blow for Rotorua Lakes Council which has worked on the $37 million wastewater upgrade since 2015.
However, the trust backs local hapū concerns, who say Lake Rotorua is a "taonga not toilet".
The trust has released a statement saying it will oppose the council's application seeking resource consent to upgrade its existing treatment plant with one that discharges treated wastewater to the Te Arikiroa Channel and Lake Rotorua at Puarenga Bay (Sulphur Bay).
Submissions on the resource consents closed last week and it is now before the Environment Court.
The lakes trust made its decision at its meeting on Friday and lodged a submission in opposition.
Trust chairman Sir Toby Curtis said the discharge proposal would be a direct conflict with the position of the ahi kā/mana whenua (tribal authority for the lake), and in relation to its values with the Te Tūāpapa o Ngā Wai o te Arawa (Te Arawa Cultural Values framework).
"As a trust, we are responsible for the sustainable and responsible oversight and
management of Te Arawa's settlement assets – including the region's 14 lakes.
"The trust supports the upgrade of the wastewater plant and the method of treating the
wastewater, however, we cannot support the discharge of this water into Te Arikiroa
Channel and Lake Rotorua."
He acknowledged the lakes council had gone to great effort in an attempt to consider cultural values for this project, which had included the development of a "contact bed" to restore the mauri (life force) of the water before it reached the lake.
"However, we also acknowledge and support the genuine concern of local hapū that the
contact bed does not sufficiently address their concerns."
He said local hapū concerns included a "loss of mana" and the "belittling of rangatiratanga".
He said that included a loss of mana to an ancestral icon - that the association of the lake with wastewater was perceived as an offence and that the discharge would have a significant negative impact on the ability to harvest, cook and clean in and around the area.
"We support these concerns. In addition, we are also concerned about the potential negative impact of 20 million litres of treated wastewater entering the lake every day."
Rotorua mayor Steve Chadwick said the recovered water from the upgraded wastewater treatment plant would be the cleanest water entering the lake from any source, including all streams, and would be significantly cleaner than the lake itself.
"We explored alternative options but there are no viable, affordable land disposal alternatives. As part of what's now proposed we thought and believed we had a method of cultural treatment that was acceptable, so we were really surprised and disappointed that at this late stage Te Arawa Lakes Trust has expressed a different view."
She said it was an important project for the community and the council needed a solution that found a balance between environmental outcomes, cultural aspirations, community affordability, practicality and what's achievable.
"We'll reflect on the material we have now received from Te Arawa Lakes Trust and will consult our Te Arawa partners regarding the implications."
Environment Bay of Plenty Māori constituency councillor for Kohi Tīpene Marr said the treated wastewater was "clear not clean". He said despite his position on the regional council, he put in a submission opposing the discharge into Lake Rotorua.
"I want to see who is going to drink a litre of it when it comes out."
"They should buy a farm and pump it out there ... I agree with the sentiment that's been used on social media that our lake is a taonga not a toilet."
Kuia Blanche Hohepa-Kiriona said her hapū, Ngāti Tuteniu, Ngāti Rangiteaorere, Ngāti Uenukukopako, Te Roro o Te Rangi, told the council they would work with them to find a solution but they "ignored their bottom line", no discharge into the lake.
"We're proud of Te Arawa Lakes Trust for having our backs on this and the backs of every ratepayer in this city because an even sicker lake, and second rate sewerage treatment plant, isn't going to be good for any of us."
Her daughter, Renee Kiriona-Retiti, who is leading the "Taonga not toilet" online campaign said she hoped the council would "see sense" and find a solution that didn't involve "threatening the earth's most precious resource - freshwater or the health of their ratepayers and all those who love to fish in this lake".
"This lake is already sick and any more pollution will be a death sentence for it."
Te Arawa Te Waka's Facebook page ran a poll last week asking followers if they were for or against treated wastewater being discharged into the lake for the next 35 years. There were 1100 votes and 98 per cent were against.
Te Taru White, chairman of Te Tatau o Te Arawa, the iwi board in partnership with the council, said the lake trust's decision was a "surprise".
"They have chosen to oppose it and that is their choice ... They have their responsibilities and role and we had a role to play in terms of the process."
White said he was comfortable with the council's consultation process, saying it was four years in the making and included 20 one-on-ones and presentations with small groups and 10 formal hui.
He said there was also a cultural assessment report done and consultation around that.
"When you put that together, that's significant consultation."
In 2013, the Environment Court directed the Rotorua Lakes Council to find an alternative effluent disposal method to replace the irrigation of treated wastewater in Whakarewarewa Forest following strong, ongoing concerns from tangata whenua.
The council had been using the forest spraying disposal method since 1991 but made a commitment to stop doing so by December 2019.
A large plume above Whakaari/White Island prompted questions.