Iwi and environmentalists are crying foul after Auckland Council suggested more than half of the submissions opposing a proposal to dredge the Rangitoto shipping channel should be rejected.
The council-owned Ports of Auckland wants to dredge up to 3.25 million cubic metres of seabed from the shipping channel and the Fergusson Terminal route over 35 years.
The council received 207 submissions on the proposal - 194 in opposition and 13 in support.
The council is recommending 116 of the opposing submissions be struck out as these raised issues that were outside of the project's scope, such as where the dredged material is to be disposed of.
Adverse effects on water quality, marine life and insufficient consultation with mana whenua were among the concerns laid out in opposition submissions that were deemed to be out of scope.
Ports of Auckland has consent from the Environmental Protection Authority to dump up to 2 million cubic square metres at an established dumping site 50km east of Cuvier Island, near Great Barrier Island.
Environmental group Protect Our Gulf's Kathy Voyles said the council was acting undemocratically.
"[The council] allows people, groups and iwi to make submissions and yet before they've even got to the next part of the process, they're struck out. What's the point?
"It really strikes me as extraordinarily undemocratic."
Kelly Klink of Ngāti Rehua Ngātiwai ki Aotea said previous dumping near Cuvier Island had already damaged the iwi's traditional fishing grounds.
Klink said their submission was struck out because it addressed the material possibly being dumped near Cuvier Island again, as well as the dredging itself.
"In te ao Māori, we look at the whole process holistically rather than individually. Wherever you might dredge or dump it has a flow-on effect to other areas."
Tangata whenua co-chair for the Hauraki Gulf Forum Nicola Macdonald called for an end to all dumping in and near the marine park.
She also urged the port to minimise dredging and find a different way to dispose of materials.
"We don't see that [the port] disposing of dredged materials off of Great Barrier Island and Repanga Cuvier Island needs to continue. It's outdated and archaic, and it doesn't belong in the 21st Century."
Auckland Council resource consents manager Mark White said in a statement the suggestion to strike out was based on rules in the Resource Management Act.
White said the application related only to dredging, so submissions relating to the disposal of material were out of scope.
The disposal of material was covered by the marine dumping permit approved by the Environment Protection Authority.
Ports of Auckland communications manager Matt Ball said the port was working to minimise the amount of dredging it carried out as it was costly.
To reduce the amount of dredging required for safe passage of ships, the port restricted ship entry to high tide and tailored how much seabed was dredged to the size of ships.
"It's sound business and it's sound environmentally to minimise that dredging, so we will only do what's necessary and only do it when it is necessary."
Previously, the port disposed of dredged material by mixing it with cement and using it in land reclamation, but sea disposal was now the best option as it was moving seabed from one place to another.
Ball said there was no indication dumping near Cuvier Island affected fishing grounds.
"[Sea] currents in that area don't go anywhere near Great Barrier, it doesn't go near land. It's highly unlikely that any of that clean material disposed out there would have any impact on fishing grounds."
A week-long hearing will begin on 22 June. Hearing commissioners will make a decision on the proposal and whether the submissions in question will be discounted.