Lake Burley Griffin is an important part of the Murray–Darling Basin’s tributary system; it acts as a water quality retention pond for downstream parts of the system. Lake Burley Griffin also supports a variety of water-based commercial and recreational uses. This means that there is increasing pressure to provide better water quality outcomes to support these secondary functions and to protect the health and safety of users. The ACT’s recreational water bodies, such as Lake Tuggeranong, Lake Ginninderra and Yerrabi Pond, are subject to similar demands as Lake Burley Griffin, and the problems are expected to be similar for all of these water bodies.
Lake Burley Griffin. Photo: ACT Government Environment and Planning Directorate
Nutrients and blue–green algae in Lake Burley Griffin
Nutrient-rich water flows into Lake Burley Griffin are the primary cause of blue–green algae blooms in the lake. These nutrients can build up in the lake as a result of inflows from surrounding urban areas that carry:
- sediments and soil flowing into stormwater drains
- fertilisers and organic matter (grass clippings and leaf litter) from gardens flowing into drains
- food scraps that have been dumped into waterways
- leakages from blocked or damaged sewers and drains.
Catchment management to improve Lake Burley Griffin water quality
Water quality conditions in Lake Burley Griffin reflect the composition of water and pollutant loads from the rivers, creeks and drainages that enter the lake, as well as biological, chemical and physical processes within the lake. The ACT Commissioner for Sustainability and the Environment has made recommendations for management interventions to help remediate the lake’s environmental and recreational values, such as:
- urban catchment water quality management, including assessing water-sensitive urban design effectiveness and future sites for installation (eg urban wetlands to filter pollutants entering the lake)
- rural catchment water quality management, including actions to reduce soil erosion from upstream catchments
- regular review of sewage treatment and discharge management for the Queanbeyan and Fyshwick sewage treatment plants
- consideration of the feasibility of flow releases from Googong Dam to increase river flows into the lake during low-flow summer periods, to dilute pollutants and improve water quality.
The ACT Government is implementing the recommendations made in the Commissioner’s report through the Lake Burley Griffin Action Plan: A Healthier, Better Functioning Lake by 2030. Specific actions being undertaken include:
- a water strategy for the ACT based on catchment management principles
- an ongoing catchment management expert panel
- a comprehensive catchment education awareness program
- a volunteer-driven Landcare program
- examination of options for enhancing water quality and vegetation monitoring to inform future actions
- water column manipulation trials
- ongoing renovation of the stormwater system, and further constructed wetlands and pollution control structures (eg gross pollutant trap maintenance and constructed wetlands to capture urban water run-off).