2021-08-10
This is a statement I made to the Legislative Assembly last week on the important work we are doing as part of the ACT Healthy Waterways program.
Our local waterways support so much life and are one of the great things about living in Canberra. Many of us enjoy visiting these waterways regularly, whether for exercise, recreation or social events. They are also hubs for biodiversity, supporting a myriad of plant and animal life.
For years now, blue-green algal blooms have afflicted our urban lakes. Lake Tuggeranong is regularly closed in summer due to outbreaks of blue-green algae, and last summer was one of the worst for blue-green algae in Lake Burley Griffin in years. Our other urban ponds are not immune to this problem either.
Blue-green algal blooms are a symptom of urban water pollution, which means that there are likely to be other, less apparent pollutants in our waterways as well.
Our urban lakes and ponds were designed to trap pollution bound for the Murrumbidgee River and downstream communities, and they are doing this job extremely well.
However, today’s community expectations are broader than just this purpose. The community also values our lakes and ponds for recreation, amenity, and for the commercial values they provide. They can be equally great places to hold a picnic or a triathlon.
Residents and businesses alike are attracted to lakeshore views—think of the Kingston foreshore. But these values are diminished every time there is an algal bloom.
The ACT Government has just wrapped up a $94M co-investment program with the Australian Government to improve water quality in the region—the ACT Healthy Waterways Project.
Nineteen water quality assets—raingardens, wetlands, ponds and channel restorations—were constructed. Over 460,000 water plant seedlings were planted in 17 of the water quality assets and these grew to cover a combined treatment area of almost nine hectares. In addition, the riparian zone of the Molonglo River upstream of Lake Burley Griffin was restored to arrest channel erosion. The area around these projects was landscaped and over 160,000 herbs, shrubs and trees were planted from a plant list of local native species.
Together these projects are now reducing the yearly load of pollutants in our waterways by an estimated average of 1900 tons. Around twenty percent of the pollution that was destined for Lake Tuggeranong is now being intercepted by the seven water quality assets built there. Feedback from residents about the water quality assets is very positive, with many locals appreciating the amenity and opportunities for exercise these afford.
Birdwatchers have enjoyed visits to the assets and drawn attention to some rare migratory visitors to the wetlands.
The estimated benefits of these water quality assets are based on water quality models.
Healthy Waterways monitored water quality across Canberra and the performance of several existing assets to improve the accuracy of these models, giving us a better understanding of their value.
Research was conducted by the University of Canberra to understand the links between pollution in stormwater and Lake Tuggeranong sediments, and the occurrence of algal blooms in the lake.
What we learned from this work is that more water quality improvements are needed.
Stormwater coming from Canberra suburbs is carrying high levels of pollution into our lakes.
Research by the University of Canberra suggests that it is possible to suppress an algal bloom in the Lakes via the use of “Phoslock” which is a clay product developed by the CSIRO which binds phosphorus in water with sediments, and reduces unwanted algal growth. Unfortunately, it was also determined that four to five times the amount of phosphorus required to sustain a bloom was still entering the lake from its catchment and this would very quickly negate the benefits of any such suppressant. Until we can manage this, there is no point in spending resources locking up the phosphorus in the lake sediments as the algae will be amply fed by phosphorus pollution entering from the catchment.
The work also shows that it will be a major challenge for water quality assets to filter out all of this pollution before it reaches our urban lakes, where it can cause problems like blue-green algal blooms.
So, water quality assets are an essential tool to improve water quality but we can’t rely on these alone to solve the problem. To stop these algal blooms, we also need to reduce catchment pollution at its source.
Every lake and pond is different, but these findings are relevant outside of the Tuggeranong catchment, which is the catchment most intensively studied. We know, for example, that Lake Burley Griffin is on the cusp of either good or poor water quality. Last summer it tipped towards poor water quality, after improvements made over the last decade. We know we need to do more to prevent pollution from entering the lake in wet years like last summer.
We need to reduce inputs of pollution from suburbs that drain into Lake Burley Griffin and be careful that any future developments in the catchment do not tip the lake towards more regular episodes of poor water quality and blue-green algal blooms.
So what steps can we take to further improve water quality? The ACT Government continues to invest in innovative ways to manage water quality problems. The ACT’s first large-scale floating wetland has recently been deployed in the Village Creek bay of Lake Tuggeranong. The aim of this wetland, together with modifications to the gross pollutant trap just upstream, is to discourage blue-green algal growth by taking up nutrients that would otherwise pollute the water.
This wetland is undergoing a two-year trial after which it will either be left in place or relocated to a stormwater pond. I had the privilege of inspecting this great industry-supported innovation when I launched the floating wetland earlier this year.
This autumn, ACT NRM and Healthy Waterways joined forces to trial a new H2OK public education program in five suburbs across Canberra that focussed on preventing autumn leaves from entering drains. Nutrients rapidly leach out of leaves on the ground, so leaves that accumulate in roadside drains contribute to the nutrient pollution in stormwater. The H2OK program encouraged householders to keep drains adjacent to their blocks clear of leaves. The results of this trial are now being evaluated by Griffith University.
The Environment, Planning and Sustainable Development Directorate has begun planning for a new program of work: Stage 2 of Healthy Waterways. In Stage 1 the focus of infrastructure was on water quality assets that filter pollutants from stormwater. But as we have just heard, water research and monitoring suggests that this approach is not going to solve the problem alone.
Therefore, in Stage 2 the Healthy Waterways team is exploring new ways to prevent stormwater pollution from occurring in the first place. Pollution is generated in urban areas because runoff is diverted to concrete channels rather than flowing through soils and vegetation, which act to cleanse it before it makes its way into waterways. So the team is investigating infrastructure to make use of green corridors and spaces within our catchments to cleanse stormwater. They are also looking into ways to store and slowly release stormwater so that it does not overload the water quality assets in the system. Plans are being drawn up in parts of the Tuggeranong catchment and in selected locations across Canberra, including in the Yerrabi Pond catchment.
It is anticipated that Stage 2 of Healthy Waterways will rely on much more than just infrastructure to improve water quality. An extensive public education campaign is planned that will focus on what households can do to prevent leaves and grass from entering drains, building on lessons from the trial this past autumn. EPSDD will also work with the Transport Canberra and City Services Directorate to understand lifecycle costs of assets and how to better manage green spaces, and continue its work with the Suburban Land Agency to reduce the amount of pollution escaping from new suburbs under development.
Plans for Stage 2 research and water monitoring are focussed on narrowing down the sources and quantum of pollution so that infrastructure can be sited where it is the most cost-effective. Water quality models will be upgraded to be more accurate and to take into account the measured performance of recently constructed water quality assets. This will allow for comprehensive catchment plans to be developed for urban lakes and ponds, as well as some rural catchments. The plans will detail various options—actions, assets and their locations—available to Government to manage Canberra’s water pollution problems, and their associated costs and benefits.
Therefore, the Government is working to build on the achievements of Stage 1 of Healthy Waterways, both for the benefit of the environment and the wellbeing of Canberra’s residents and businesses that make use of waterways.
Because, as the recent and comprehensive Dasgupta Review on the Economics of Biodiversity emphasises, environmental health is not an alternative to economic health but a contributor to it.
The Dasgupta Review is an independent, global review on the Economics of Biodiversity led by Professor Sir Partha Dasgupta who is the Frank Ramsey Professor Emeritus of Economics at the University of Cambridge. The Review was commissioned in 2019 by the British Treasury and has been supported by an Advisory Panel drawn from public policy, science, economics, finance and business interests.
Healthy catchments produce clean water that not only benefits aquatic flora and fauna but all those who rely on our lakes and ponds, including businesses and community.
This information highlights the strong correlation the Healthy Waterways initiative has with the Wellbeing domains, namely Environment and climate, Social connection and Living standards respectively.
The cost–benefit analysis of the original Healthy Waterways initiative shows the program has present value benefits of $127 million and present value costs of $76 million. Sensitivity analyses indicate the net present value ranges from $24 million to $126 million and the benefit–cost ratio ranges from 1.3 to 2.6. These results indicate that the program was economically viable as the benefits of the program outweigh the costs.
I would like to commend the achievements of the Healthy Waterways initiative and congratulate the small, dedicated team at EPSDD who delivered this work.