Environment

The nearly $100 million effort to clean up Canberra’s waterways

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ACT Healthy Waterways project manager Justin Foley and Martin Boyd from lead contractors Construction Control on the site of the Holder wetlands.

Photo: Elesa Kurtz

The big-picture aim is to improve the quality of the water in Canberra's lakes and river systems but the campaign has its roots in the humble gutters and driveways of the national capital's suburbs.

The focus is on improving water quality higher up in the catchment where rainwater becomes stormwater. That means physical infratructure to filter the stormwater, but also a campaign to change the mindset of Canberrans, to help them understand that blowing leaves down the gutter or hosing off the driveway sends pollutants ultimately to our waterways.

The biggest cause of water pollution in lakes and waterways is contaminated stormwater run-off from streets, house blocks, development sites, retail and industrial areas. Leaf litter is one of the biggest contaminants, overloading waterways with nutrients, contributing to the blue-green algae outbreaks.

The ACT Government says "every house in Canberra is uphill from our waterways so every drop of water we use as well as all the rainwater that falls ends up in the lakes''.

"We're retro-fitting older suburbs where in the 1950s and 1960s, the focus of stormwater management was on mitigating the risks of flooding,'' Mr Foley said. "But its become clear that we needed to deliver a better water quality outcome and we all have a role to play in that.''

Wetlands under construction at Holder, off Dixon Drive, is one of the 19 projects. The finished wetlands will eventually contain about 2.4 million litrees of water, about the same as an Olympic swimming pool.

The wetlands at Holder will be gravity fed by the stormwater, making for some engineering challenges.

Photo: Elesa Kurtz

Water will be diverted from existing stormwater pipes in the area to the wetlands before flowing into Weston Creek and the Molonglo River.

The stormwater will pass through gross pollutant traps first to collect larger rubbish, collected ultimately by maintenance crews . It will also travel through ponds where sediment will settle on concrete bottoms and be collected and disposed of using a bobcat, likely ending up in landfill. Then the water will pass through the wetlands where plants will filter out the nitrogen and phospherous, before going into Weston Creek, a lot cleaner than it started.

The wetlands will not be filled with water until the plants are established. At Holder, construction is due to finish mid-year but the wetlands won't be fully functional for another two years after that. The wetlands are gravity fed and will be filled by the stormwater, once the timing is judged to be right to open the pipes.

Other projects include rain gardens which "look like a garden on the surface but have a storage and filtration structure underground that reduces nutrients from stormwater before it enters the drainage system''.

Another major wetlands project is at Isabella Pond in Tuggeranong, which will eventually be stocked with native fish. Almost 1.6 tonnes of carp were removed from Isabella Pond 12 months ago.

Mr Foley said the projects would also add to the amenity of the areas. Wetlands built in Dickson in 2011 had attracted birds, animals and reptiles and were used by the community for walking, riding and other recreation.

Twenty-one projects have been selected for the funding, 19 infrastucture and two research:

  • Wetlands Isabella Pond Under construction
  • WetlandsBetween Dixon Drive and Cotter Road, Holder Under construction
  • Rain gardenUpstream from Upper Stranger Pond Under construction
  • Waterway restorationBetween Corlette Crescent and Charleston Street, Monash Under construction
  • Rain garden Flood Memorial site near Service Street, Curtin Under construction
  • Pond Athllon Drive, Mawson Under construction
  • Rain garden Athllon Drive between Langdon Avenue and Fincham Crescent, Wanniassa In final design
  • Rain gardenFadden Pines Reserve In final design
  • Pond Between Kett Street and Drakeford Drive, Tuggeranong In final design
  • Waterway restoration Upstream of the confluence of the Queanbeyan and Molonglo Rivers, Oaks Estate In final design
  • Rain gardens Alanbar Street and Kenneth Place, Queanbeyan In final design
  • Waterway restorationYarralumla Creek, Lady Denman Drive, Yarralumla In final design
  • Waterway restoration McCulloch Street and Cotter Road, CurtinIn final design
  • Wetland Corner of Ginninderra Drive and Copland Drive, Evatt In final design
  • WetlandCroke Place, McKellar In final design
  • Waterway restoration Tattersalls Crescent, Florey In final design
  • Wetland Eyre Street, Kingston In final design
  • Wetland between Matina Street and Monaro Highway, Fyshwick in final design
  • Wetland Jerrabomberra Creek, Fyshwick In final design
  • Research In-lake Lake Tuggeranong Monitoring underway
  • ResearchPond West Belconnen catchment, Lower Molonglo catchment, North Canberra Monitoring underway

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Megan Doherty

Megan Doherty is a reporter for The Canberra Times

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