What lies beneath? Monitoring our urban streams

  • Published Date 10 Jan 2019

Greater Wellington Regional Council will shortly be heading underground in the next phase of a project to see what's alive in Wellington's network of underground piped streams.

Residents of some of our inner city suburbs won't realise it, but freshwater scientists contracted by Greater Wellington will be crawling through confined spaces to set traps and mount low-light motion detection cameras to see what fish and invertebrates are moving through the pipes.

Their task is to identify what's living in our piped streams to help us understand the health status of the habitat piped streams provide, all of which is ultimately about protecting our environment.

"This is the first phase of our underground survey and we'll be focusing on piped streams in Miramar, Hataitai, Wellington CBD and Island Bay,” says Greater Wellington Senior Environmental Scientist Dr Evan Harrison, "It's a trial to see what results we can get, with a view to monitoring other areas in the future."

This new underground phase follows three years’ work on sampling above ground streams throughout Wellington through an Urban Stream Project partnership between Greater Wellington and Wellington City Council.

Before Wellington's major earthquakes in 1848 and 1855, the city was made up of a network of rivers, streams, wetlands and swamps. Most of the waterways were severely polluted and were prone to flooding, so the solution was piping and culverting the streams underground. Today, more than 95 percent of the waterways in the city are piped underground.

"We want to assess how healthy our urban streams are, by identifying the fish and macroinvertebrates that live there, both above ground and in pipelines. This will provide a benchmark for improving ecosystem health. Results from around the city have varied depending on what the habitat is like and whether there are barriers to fish movement such as culverts," says Evan.

"Most Wellingtonians experience our thriving birdlife and flourishing restoration planting efforts, but many of us are disconnected from our streams," says Daniela Biaggio, Urban Ecology Manager at Wellington City Council.

"Our above ground surveys are showing that despite the amount of development and pollution, our urban streams still hold wildlife treasures such as kōaro and tuna longfin eels.  Finding out how streams and their inhabitants are affected by pipes will open up opportunities for how we can restore our streams and improve their health. Our wellbeing is tied to the health of our streams and it is great to know we can take action to improve them."

Evan Harrison says the amount of life in the streams depends on what's upstream of them.

"Contaminants from cars, roads, roofs and driveways, people washing cars or the disposal of paint or sediment into stormwater drains can have a detrimental impact on the level of healthy life in the waterways."

Recently Greater Wellington environmental scientists found a kōaro, a whitebait species which is classified as "at risk: declining" in Kumutoto Stream near Victoria University.

"To get there this fish would have had to climb through piped sections of the stream under the city, all the way from the harbour! It really brings home to us the importance of looking after our city waterways to protect the fish that are literally living under our feet."

Evan Harrison adds that people can help protect Wellington city's waterways by disposing of paint, oils and other chemicals at the landfill; putting litter and cigarette butts in a bin; washing cars on grass; and picking up their dog's poo.

If you see anyone dumping material down drains or funny colours in streams, report it to Greater Wellington’s environmental pollution hotline 0800 496 734.

Updated April 28, 2022 at 10:50 AM

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