Inquiry told of illegal' discharges into reserve

A visualisation of the Waterview connection. Photo / Supplied

Plans by the Transport Agency to treat stormwater runoff after upgrading an Auckland motorway causeway follow years of illegal discharges into a marine reserve, says the Royal Forest & Bird Protection Society.

The society's conservation manager, Mark Bellingham, has said in written evidence to a board of inquiry considering the $1.7 billion Waterview Connection project that the agency's predecessor, Transit NZ, was required to apply in 2001 for new rights for discharges from the Northwestern Motorway into the Motu Manawa (Pollen Island) marine reserve.

Yet Dr Bellingham said the society had been unable to find any evidence that an application was made or any discharge consent was granted.

Although much of the hearing has been focused on proposed new motorway tunnels through Waterview, the Transport Agency also wants to widen the Northwestern from St Lukes to Te Atatu, for which it will enlarge and raise by 1.5m a causeway built in 1952 with no stormwater treatment features.

The agency is counting plans to treat 80 per cent of stormwater runoff from the enlarged causeway as mitigation for the loss to the project of part of the marine reserve, which was gazetted in 1995 on a nomination of Forest and Bird.

It is also offering to restore coastal wildlife habitat along the motorway corridor, which cuts through Traherne Island, and to provide replacement planting at a park between the motorway and Pt Chevalier.

But Dr Bellingham said the removal of contaminants from stormwater discharges to the marine reserve was what the agency and its predecessor had been required to do in any case since at least 2001, and should not be counted as mitigation.

Among mitigation measures sought by the society are a replacement area of marine reserve along Te Atatu Peninsula and a redesigned culvert to help with the tidal flushing of Waterview Bay, which it believes is needed for healthy mangroves.

Earlier, Transport Agency marine ecology consultant Sharon de Luca said greater water flows might stir up buried contaminants, causing adverse effects.

Forest and Bird advocate Bill McNatty told the inquiry a report submitted by the Transport Agency estimated the section of the motorway included in the project already generated 29 tonnes of sediment, 379 kilograms of zinc and 56kg of copper annually.