The Green Party has criticised plans for what it calls a mega-sewerage system in the Bay of Islands.
The Far North District Council is proposing a multi-million dollar treatment scheme, draining into wetlands at Waitangi.
The Bay of Islands has been plagued with sewage spills for many years, with frequent reports of illness from polluted shellfish.
Green Party co-leader Russel Norman says the Waitangi scheme is aimed mostly at supporting wholesale new property development.
He says the council's priority should be fixing the many smaller schemes around the north that are failing.
Dr Norman says there is evidence that most shellfish sites do not meet water quality guidelines.