A landmark decision will allow a mining company to dredge 50 million tonnes of ironsand a year from the South Taranaki Bight using a giant magnet, the Environmental Protection Authority says.
The EPA today released its decision in favour of Trans Tasman Resources consent application lodged 12 months ago.
The final decision was split 2:2 between the four members of the decision making committee, with chairman Alick Shaw, making the casting vote to approve the application.
The company's application for consent covered an area of 66 square kilometres between 22km and 36km off the west coast of South Taranaki within New Zealand's exclusive economic zone.
The proposal to mine and export titaniferous iron sand was called "a sustainable and world leading development" and would have little environmental effect, the company said.
It had been opposed by Kiwis Against Seabed Mining (KASM), Patea - based iwi Ngati Ruanui, and Talley's Fisheries who also submitted against the mining when a previous application by TTR was declined by the EPA in 2014.
KASM and Ngati Ruanui said they will appeal the decision.
Last year a 6000 signature petition was presented to parliament by KASM and Ngati Ruanui calling for a moratorium on seabed mining.
Much of the concern from opposing groups focused on a sediment plume from the mining process which would be widely dispersed back to the seabed during the dredging.
The plume would affect marine animals living in and outside of the proposed mining area, objectors claimed.
Research by the council found at least five threatened species of invertebrate lived within the proposed mining area.
In August TTR updated its application with further scientific and engineering research, and refined the environmental impact.
Under the application the company plan to dredge up to 50 million tonnes of iron sand each year by separating ore from the sediment on a processing ship.
Around 44m tonnes, or 90 per cent, of the sand would be returned to the seabed into previously mined areas.
The sea floor where the dredging will take place contained no significant marine features, and was an area of significant wave and tidal action.
TTR estimated the project would generate between $20m and $160m in local, regional and national GDP, and provide between 300 and 1650 jobs.
The project would also generate between $45m-$300m in expenditure in Taranaki and nationally, and also add to government income through taxes and royalties, TTR said.