Bird lovers see positives in road plan

Guardians of a marine reserve in the Waitemata Harbour see potential for environmental gains from widening the Northwestern Motorway into the reserve.

Although the motorway is likely to be widened by 3m to 5m into the Motu Manawa-Pollen Island Marine Reserve, to cope with extra traffic from the $1.15 billion Waterview link, conservation organisation Forest and Bird believes that will open opportunities for repairing and reducing long-standing environment impacts.

The Transport Agency intends widening the motorway from St Lukes to Westgate over more than 10 years for about $860 million, including upgrading interchanges and raising a marine causeway between Waterview and the northern end of Rosebank Peninsula to protect it from floods at an earlier stage.

It has promised to add stormwater treatment facilities missing from when the causeway was built in the 1950s, and to work with the Department of Conservation and Forest and Bird on revegetating the area.

Its plans to encroach on the marine reserve have raised some concerns among Auckland Regional Council members, who maintain a link between the Northwestern and Southwestern motorways could have been built along Rosebank Peninsula from Avondale with less environmental and social disruption than through Waterview.

Up to 447 homes are expected to be destroyed by a Waterview link, including 83 potentially needed for a wider Northwestern.

But Forest and Bird's Auckland Central branch chairwoman Anne Fenn, whose organisation applied in 1995 for the marine reserve to be created, says plans to upgrade the causeway open the door to remedy some of the motorway's adverse impacts.

She said water quality in the reserve could be improved with more culverts under the motorway to maintain tidal movement and to stop silting in Waterview Bay. Weeds beside the motorway, particularly through Traherne Island, were also a problem and removing them would be a very positive step.

"Not only would it help beautify the area pre-World Cup, but it would help save habitat for animals living there and remove a growing seed source for other weeds to invade neighbouring areas," Mrs Fenn said.

As the area was a rare habitat for semi-flightless fernbirds, and a royal spoonbill was, unusually, sighted there last month, extra care should be taken to protect it.

Transport Agency official Paul Glucina told a regional council transport committee meeting separately that adding a lane to each side of the motorway was likely to mean extending the causeway 3m to 5m towards the marine reserve's extensive saltmarsh zone.

But he said a preliminary indication from the National Institute of Water and Atmospheric Research was that it would have no impact on the functioning of the saltmarsh.

Council chairwoman Christine Rose said it was sad to see rubbish mar planting efforts.