An image of the area where gathering shellfish and whitebait is prohibited due to problems with the Motueka Wastewater plant. Photo: Supplied/ Tasman District Council
Ngāti Rārua is calling on the Tasman District Council to accelerate essential repairs to the Motueka Wastewater treatment plant, almost a month after problems were detected with its filtration system.
Tasman District Council engineers noticed in late September that the final membranes in the filtration system were degraded, and not working as expected.
The council's team leader of water supply and wastewater Becky Marsay said the membranes removed any remaining bacteria and minute particles before the water was discharged from the processing plant.
Marsay said the team were at a loss to explain why this was happening, however, it was likely the membranes would need to be replaced.
"Sourcing new membranes or having them manufactured, then getting them on to site and installed could take several months."
The council has reverted to using an older system, where partially treated wastewater is pumped into an adjacent soakage area and filtered through the ground.
This treatment method was retired several years ago but was being used again to avoid uncontrolled wastewater overflows.
Warnings were issued against collecting shellfish or whitebait and Te Tauihu iwi placed a rāhui across the Motueka coastline last week.
Te Rūnanga o Ngāti Rārua pouwhakahere Shane Graham said a long-term solution was needed to protect the health of people and the taiao.
Despite action being taken by the Tasman District Council to cope with the equipment failure - partly treated wastewater had entered estuarine areas around the Motueka River.
Graham said it was likely to have entered the tupuna awa and moana and the plan to replace the membranes needed to be accelerated.
"The council's own planning acknowledges that with climate change and rising sea levels predicted to have increasing effects in the coming years, our estuaries will be more vulnerable to inundation and storm surge."
The Wastewater Activity Management Plan shows the plant, which services Motueka, Riwaka and Kaiteriteri, is scheduled for replacement in the 2030s.
Graham said it was not an asset to "sweat to the point of failure" and the iwi wanted the scheduled replacement of the plant to be brought forward.
"We simply cannot risk the health or the mauri of the taiao in one of Aotearoa's most beautiful areas."
Graham said moving the plant to an inland location, where the treated wastewater could be discharged to land rather than awa or moana was a far better long-term solution.