24 January 2022

Recent rain sends Lake Tuggeranong's floating wetlands, well, floating

| Lottie Twyford
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Tuggeranong floating wetland

The Tuggeranong floating wetlands will need to be moved after the recent spate of wet weather. Photo: ACT Government.

The trial of floating wetlands in Lake Tuggeranong, which were intended to help address recurring algae problems, has hit a bump in the road (so to speak).

Recent wet weather and wild storms have caused the 500 square metres of wetlands to dislodge from their bearings, so they will need to be repositioned.

The wetlands are part of a two-year trial funded by the ACT Government through the ACT Healthy Waterways program.

Initially, the wetlands were strategically installed at the inlet where Village Creek enters the lake – a spot previously identified as an algae-producing haven.

It was hoped the wetlands would compete directly with algae for both light and nutrients and stop algal blooms from being formed in the bay so they couldn’t then wash into the lake.

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Unfortunately, although the bay is generally quiet, recent storms meant the water became turbulent and water levels simply became too high, program manager Dr Ralph Odgento explained.

“We thought good anchors to both banks and long tethers would allow us to overcome these problems as the wetlands could float above it all. But, in the first storm a few months ago, one side of the anchors actually ripped out of the banks,” he said.

So the team acquired better anchors and re-anchored the wetland to the bottom of the lake instead of the bank.

This didn’t work either.

“The anchors didn’t fail, but the wetlands were just buffeted in the turbulent flows of the water.

“The flows were just too much for the wetlands – one ended up on top of the other,” he said.

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Despite the setbacks, it’s not the end of the trial. The wetlands will most likely be moved to a quieter location in the lake.

“We haven’t decided exactly where yet, but we need to find a less turbulent environment for them,” Dr Odgento said.

It might also mean they aren’t as effective as originally hoped.

While they will still work indirectly by lowering the overall nutrient level in the lake, they won’t be able to work in the bay where they could directly compete with algae for light and nutrients.

Lake Tuggeranong has long been plagued by hazardous algal blooms, particularly in the warmer months. This means the lake is often not safe for swimming, water sports, or other activities.

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Dr Odgento, however, is realistic about the impact the wetlands can have on the lake’s overall water quality.

“They are a very good water-quality asset, but they on their own would not be able to intercept enough nutrients to prevent algal blooms in Lake Tuggeranong,” he explained.

There’s also the issue of the plants on the wetlands needing to grow before they can be fully effective.

“They are, however, one piece of the puzzle to mitigating the algal blooms in the lake,” Dr Odgento explained.

While measuring the success of the floating wetlands is also a challenge, Dr Odgento is hopeful he and his team will be able to find a way to do so before the trial comes to an end.

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Capital Retro5:17 pm 25 Jan 22

A lot of doggy doo contributes to our waterways pollution.

Anyone else get the sense that after a decade of failures on Lake Tuggeranong that the water experts and researchers don’t really know what to do and that they just keep using Lake Tuggeranong as a cash cow for minor experiments on water quality.

If I hear another water expert on Canberra radio or in print talking up their next ‘amazing’ plan for Lake Tuggeranong.

They talk a ‘big game’ pre project, then go small game after they get funding for their trial.

Turning an artificial pollution trap into a clean waterway with actual amenity is a huge ask with countless unknowns. It was always going to require lots of experimentation. Remember, to a scientist a failed experiment is not a failure, you have just learnt something you didn’t not anticipate. And I cant blame those facing the media for getting excited about new trials. If, like me, they are passionate about environmental management these are genuinely exciting experiments.

The problem is that short of getting rid of the Lake entirely, there is no easy (or cheap) solution.

Most of the problems are catchment related, where solutions are more difficult and expensive. There wasn’t too much thought given to long term water quality in our lakes before they were built and so here we are.

Although this is one area that the ACT Government does deserve some credit on, recognising the issue and attempting to address it with various projects. They obviously aren’t there yet, but there’s good work being done.

Tuggeranong’s water quality has not been getting better. I didn’t know you were such an easy marker on the score of ACT government are doing a good job.

BTW, I certainly know it’s not an easy fix. No one has ever said that.

Problem is that ACT Government has used a big chunk of the massive Federal waterways funding to build the Holder wetlands and new water facilities around the new Molonglo suburbs. Also pumped money into Barr and Rattenbury’s local Lyneham wetlands. ACT Government only provided 10% of the funding but primarily directed the funding decisions.

A lot of the proposed projects and trials for Lake Tuggeranong weren’t funded despite most experts conceding Lake Tuggeranong was the worst water area and most in need. Individual Project funding was often based on political imperatives and community consultation.

These same issues and promises for Lake Tuggeranong have been going on for years. We keep hearing about upcoming solutions for Lake Tuggeranong and then finally “we’ll continue to look at management interventions for Lake Tuggeranong “.



Whilst I think politics definitely influenced early parts of the project, Tuggeranong has since seen the construction of the Kambah Wetlands, Isabella pond being rebuilt as well as a number of smaller rain garden projects and similar.

And that’s not even mentioning the floating Wetlands and other research projects on Lake Tuggeranong that are ongoing.

As above, the problem is big and not easily fixed.

Of course the issues are catchment related, the lake was designed to be part of a pollutant trap sitting between the suburbs and the Murrumbidgee!

The ponds in Gungahlin the same, though at least they are not referred to as a lake and their function a little more obvious.

Just how bad does the water quality have to be before you guys start to question things?

How many failed water improvement projects, how many closed days on the lake, how bad the smell, how much redirected money to fund other projects, how many out of priority order water projects in ministers own electorates, how much poorly designed cement hardscaping from new housing developments built too close to the lake, how many empty promises to improve things, how many human error mistakes, how many ignored recommendations from government reports, how many catchment filter traps not cleaned to schedule and how many water experts complaining about the management of Lake Tuggeranong does it take for you guys to think “actually on reflection, something isn’t working that well”.

I would have thought this was an open and shut case compared to other grey area issues discussed on this website. I’m at a loss how anyone can so easily defend the current management of Lake Tuggeranong.

The construction of the many ponds, wetlands and rain gardens has only recently finished. Many of them require up to 2 years of growth before they begin to be effective in up taking nutrients. And after that there’s the issue of the lake already being saturated with nutrients (not to mention the carp problem inhibiting water plant growth in the lake itself). This is a VERY long term project because it has been a VERY long term problem. Criticism of project only funded since 2014 for not yet fixing a very complex problem shows a deep misunderstanding of the time scale of this kind of rehabilitation project.

I don’t think I could disagree with your last comment more.

That’s because you think the efforts on Lake Tuggeranong have been a good.

I’m not just criticising this project from 2014, I’m criticising two decades of broken promises, failed projects and the redirection of water funding to other projects.


To be honest, It’s because I think you’re uniformed on the scope and causes of the problem, the research that has been occurring in the area and I disagree with your overall assertions around what has happened with specific projects and funding.

Ha, that should read uninformed, not uninformed.

BJ, on that link you’ve provided, have you actually read the ICRC report on secondary water uses and why the original proposed projects were canned?

As I said above I believe there was some politics involved early in the piece, but since then it really hasn’t been a big impact on what’s occurred.

The problems in Tuggeranong’s water quality goes way beyond that.

Of course I’ve read it Chewy. I’ve even read the 1978 report for the ‘proposed Lake Tuggeranong’ that highlighted the potential for the current issues with the Lake if proper management, care and maintenance wasn’t undertaken.

I also used to read the reoccurring pre election brochures from my local members along the lines of “Labor to fix Lake Tuggeranong”.

I’ve read the plethora of reports on water quality with recommendations that were adopted in principle but not adopted in practice.

I’ve read the project funding proposals with grand promises and impressive solutions.

I’ve read the analysis showing Lake Tuggeranong was the most polluted waterway in the country and most of the blame was placed at the feet of rubbish. Things like cigarette butts and plastic lids not being caught in the ineffective and unmaintained lake filter system.

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