Former Sewage Farm to be a Bird Sanctuary

Forest and Bird, Issue 307, 1 February 2003, Page 42

Former Sewage Farm to be a Bird Sanctuary

and

SARAH GIBBS

ANNE FENN

describe the recovery of 500 hectares on the Manukau Harbour.

sewage-treatment Ane covering 500 hectares in Auckland has been restored as a habitat for wading birds. Forest and Bird has played an active role in having the sewage plant upgraded and replaced with an area of ponds and bird roosts. The Mangere sewagetreatment plant was established in the 1960s on the Manukau Harbour by the erection of a series of ponds linking the foreshore with Puketutu Island. The plant took all the sewage, industrial waste and stormwater from central Auckland, Manukau and Waitakere cities. At the time it was built, the Mangere plant was considered by many to be a massive improvement on discharging raw sewage directly into the Waitemata Harbour on the

other side of the isthmus. Yet, by the early 1990s, pressure from local communities culminated in agreement that an upgrade was necessary. The initial proposal was for

an extended pipeline, meaning effluent would simply be disposed of further out into the Manukau Harbour. However, environmental groups, including Forest and Bird, successfully argued that the emphasis should be on treating the effluent to a standard where a near-shore discharge would be an acceptable option. The advocacy from environmental groups had two important outcomes. Firstly, it resulted in the development of a new ultra-violet wastewater treatment plant — considered world-leading technology. This in turn meant that the old treatment ponds were no longer required and could be decommissioned. The money saved from not having to build an extended pipeline meant that funds set aside for this could be used for environmental restoration. The decommissioning of the treatment ponds meant that seven kilometres of coastline was available for restoration. Environmental groups argued that the coastline should be restored, as near as possible, to

how it was before the sewage plant was commissioned. This included eco-sourcing coastal plants, and restoring the Mangere Tuff Crater (also known as the Mangere Lagoon) to its original tidal state. Another key part of the restoration plan has been the construction of several large bird roosting areas. The northern harbours of New Zealand (including the Firth of Thames, Manukau and Waitemata harbours of Auckland) are generally considered by ornithologists to be internationally important. The Manukau is visited, for example, by large numbers of international migratory birds, including up to 7500 eastern bar-tailed godwit and 7000 lesser knots. These species breed in the tundra of Siberia and Alaska, but migrate to New Zealand to escape the Arctic winter. Many native species live in these harbours all year round, including pied stilts and royal spoonbills. Other native birds, such as pied oystercatchers and wrybill, breed in the South

Island, but migrate to northern harbours including Manukau. More than 60 percent of New Zealand’s wading birds use the Manukau Harbour either for the whole winter, or for pausing en route to another harbour. Some fly between the Manukau and other harbours around the Auckland region so they can feed for extended periods, following low tides in different harbours. With increasing development and other pressures around Auckland’s coastline, roosting areas are at a premium. Bird roosts constructed as part of the Mangere project will provide vital habitat for both native and migratory birds. An added bonus is that the new roost sites will draw birds away from Auckland International Airport, where they are a significant hazard to aircraft landing and taking off. Although the area is still closed while construction is ee

completed, the Mangere foreshore will be marvellous place for recreation once restoration is finished. Coastal walkways, viewing platforms and bird hides have been made an integral part of the landscaping. The estimated time of completion is October 2006 but, with work almost two years ahead of schedule, the area could be open to the public long before then. — SARAH GIBBS is northern field officer for Forest and Bird. ANNE FENN is a member of the national executive. quam * ae ar wen,