Whanganui District Council's discharges of sewage into the sea have been branded a health risk and "repugnant" at a resource consent hearing.
The hearing in the council's application to continue to discharge sewage into the Tasman Sea was held last week.
After two days of submissions, the panel adjourned for the hearing.
The council wants consent to discharge milli-screened effluent via the existing ocean outfall located 1800 metres off Castlecliff's South Beach.
It wants a three-year consent from Horizons Regional Council while its new $38.7 million wastewater treatment plant is built.
But a report by coastal scientist Shane Kelly, of Coast and Catchment Ltd, said he did not consider the milli-screening to be an appropriate form of wastewater treatment for a population of around 36,000 residents.
"The assessments clearly indicates that the current discharge poses a health risk, and affects water quality, sediment quality and benthic ecology," the report said.
But Mr Kelly agreed there was no better alternative and said a short-term consent would give time to produce an economically and environmentally better solution.
Meanwhile, a joint iwi statement from Whanganui/Tupoho, Wairiki Ngati Apa, and Ngaa Rauru Kii Tahi opposed the consent - though also said, should consent be granted, iwi wanted to establish agreed protocols with council.
"The practice of discharging wastewater to sea is repugnant to iwi. It violates the mauri o Tangaroa and breaches tikanga and kaitiakitanga," the statement said.
Iwi wanted a condition of the consent to be the establishment of a Iwi Advisory Group to work with council on various wastewater matters, including the design and development of the new sewage plant, appropriate cultural and environmental monitoring, implementation of cultural restoration and support projects and promotion of alternative waste disposal options at source.
Horizons Regional Council group manager strategy and regulation Nic Peet said the hearing had not yet closed and Horizons was waiting to hear from the panel about when a decision would be released.