Fears for native species in Wellington stream if huge reservoir goes ahead

Mount Cook resident Frank Cook showing the site of a major slip into the stream. Photo / Mary Hutchinson.

A Wellington stream could be devastated by plans to build one of the country's biggest reservoirs, according to concerned locals.

The Prince of Wales, or Omaroro, reservoir is planned for Prince of Wales Park in Mt Cook. It will hold 35 million litres of water, the equivalent of 14 Olympic-sized swimming pools, but residents are worried about its impact on the surrounding area.

There are concerns heavy machinery using a small track near Papawai Stream will cause land slips and pollution, which will have flow-on effects throughout Wellington's waterways.

Papawai Stream is home to several endemic species, including the banded kokopu, koura, otherwise known as freshwater crayfish, and native eels.

A child holds a koura, one of New Zealand's freshwater crayfish, that was found in Papawai Stream. Photo / Mary Hutchinson.

Mt Cook resident Mary Hutchinson said there were already problems with slips and sediment, which can expose old rubbish.

"There's a lot of fill, or old tip material which constantly appears on the sides of the stream.

"Ancient bits of wiring, shoes, clothing, plastic bags, all kinds of weird stuff."

Hutchinson said they even found some old records once, one of which was still able to play.

"The stream and local ecology can't cope with any more assaults."

She said sediment from land slips filled the cracks between the rocks in the stream bed, destroying the habitat for insect life "which is what the fish and koura are dependent on for their food source".

Papawai stream is home to banded kokopu, which won't enter streams unless they can smell an adult fish. Photo / Mary Hutchinson.

These fears about stream ecology were raised by both individuals and community association Mt Cook Mobilised in reservoir submissions to Wellington City Council last month.

Fellow resident Frank Cook also had concerns about the submission process.

"One submitter didn't see the connection between the reservoir and the stream, [but the reservoir] could have a really severe impact on the stream," he said.

Wellington Water project director Ulvi Salayev said minimising ecological impacts, including for Papawai Stream, was a key focus of the project.

"Wellington Water and Wellington City Council have recently invested a considerable amount of money in the rehabilitation of the stream and the reduction of flooding risk so will continue to ensure that it is protected from the impact of construction and heavy vehicles."

Those fighting to preserve the stream are hoping to make headway by raising awareness of the waterways running through the city.

Hutchinson and Cook unveiled their stream-mapping project at the Community Central forum last night, which they designed alongside Victoria University student Birgit Bachler.

The project, which they hope to make interactive, will allow people to plot photos they take with GPS, and add their own stories about the stream.