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Christchurch City Scene
November 2002

Lead Stories

Leaky home moves

A celebration of Aranui

Reflections on peace

Sculpting new Gallery's skin

Wastewater plant 40

 

Back to the November Index

Summer on the way: it's sea lettuce time


Administrative work over the winter means the City Council is ready to deal with sea lettuce build-up in the estuary this summer.

In warm conditions the plant can increase its mass by up to 35 per cent a day so it is fortunate that conditions are rarely ideal. Last summer more than 600 tonnes was collected along the Southshore foreshore and taken to the landfill. A similar or greater amount is expected to be removed this summer.

Over the winter the Council has gained Environment Canterbury (ECan) permission to try small-scale removal and control trials at nine sites, including McCormacks Bay, within the Estuary. It also sought, and got, permission to keep removing sea lettuce buildups along Southshore.

The Council has a three-year consent to try a range of waterborne and shore-based manual and mechanical methods.The first in a series of small-scale trials began this month and public notification has been given.

ECan says the Southshore removal operations can continue for another five years, using tractor-mounted rakes, loader and truck and the number of days a year the crews can work has been increased from three to six. As well, the area was extended slightly to include the foreshore from Tern Street north to the south end of Estuary Road.

A programme to regularly monitor sea lettuce growth and accumulation at 17 sites around the estuary has recommenced. Remote monitoring using satellite imagery and colour and infrared aerial photography is also being investigated.

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