A water scientist says Canberra's network of concrete channels carrying stormwater to the city's lakes are a planning tragedy, largely responsible for growing summer stench along the foreshores.
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But Ian Lawrence, who has studied the lakes extensively, believes broad grassy banks on either side of the channels are a great opportunity for creating wetlands and fixing the problem.
Mr Lawrence has recommended six wetlands to overcome Lake Tuggeranong's summer stench, which drives people indoors.
He says grassy easements could be developed into suburban wetlands, trapping nutrients that now race unchecked down the concrete channels into the lakes where they feed blue green algae outbreaks.
''One of the great opportunities in Canberra's stormwater design is we have very substantial easements with the ability to limit the 100-year flood to those easements, so all housing is clear of a 100-year flood,'' Mr Lawrence said.
''While the water flows down those channels very quickly - in fact they only take one-in-five-year and one-in-10-year flows - the bulk of the big, one-in-100-year flood condition is actually through those grassed easements, so there is an opportunity in a number of places to accommodate wetlands within those easements.''
Mr Lawrence described the concrete channels as the city's great tragedy. ''We could have done much better had we integrated [wetlands] during construction of the suburbs and limited use of concrete channels.''
The Southern ACT Catchment Group says the ACT Government has agreed to construct two wetlands at Tuggeranong should it receive $85 million from the Murray Darling Basin Authority.
The wetlands would improve water quality at Tuggeranong, Yarralumla and Ginninderra by June 2016, according to the Parliamentary Agreement, which catchment chairwoman Glenys Patulny said Chief Minister Katy Gallagher confirmed at a Tuggeranong Community Council.
The commitment is also in the parliamentary agreement with the Greens to support Labor's fourth term of office.
But Environment Minister Simon Corbell said earlier this month no specific commitment existed.
While Mr Lawrence has assessed the economic impacts from blue green algae pollution in Lake Burley Griffin, which prevents international and national rowing, triathlons, marathons, skiing and dragon boat racing on the lake, he said it was more difficult to quantify the cost of Lake Tuggeranong's odour and health issues.
Retrofitting wetlands was expensive, involving breaking into the drainage system.
Mr Lawrence said the suggestion to divert significant stormwater flows through Tuggeranong Homestead's old creek line and incorporate wetlands through that system would be a cost-effective solution for some of the catchment.
Tuggeranong and Woden's steep channels would make it difficult to create shallow wetlands.
In North Canberra wetlands had been built from $200,000 up to $800,000.
The low-scale ones fitted neatly into neighbourhoods, where residents took ownership of them.
A residential developer realised wetlands would enhance land near the O'Connor shops and included in the project $200,000 for the David Street wetland.
Community and catchment groups hope the Land Development Agency's new Southquay development on both sides of Lake Tuggeranong achieves a similar outcome to make the foreshore more attractive for unit owners.
