Friends of Grasslands
supporting native grassy ecosystems
PO Box 987
Civic Square ACT 2608
Phone: 02 62.. ....
The Office of the Commissioner for
Sustainability and the Environment
PO Box 356
Dickson ACT 2602
Dear Dr Cooper
Investigation into the state of the water courses and catchments for Lake Burley Griffin: terms of reference
As you know, FOG is a community group dedicated to the conservation of natural temperate grassy ecosystems in south-eastern Australia. One of FOG’s particular concerns is the restoration and conservation of the nationally threatened species and grassy ecosystems that exist on the lands adjacent to Lake Burley Griffin. The catchment of Lake Burley Griffin contains some of the most valuable remnants of grassy ecosystems left in south eastern Australia, examples being Yarramundi Reach and Stirling Park. While not our primary mission, FOG also advocates good management of freshwater biodiversity. We hold the view that actions on the adjacent land will impact on the Lake and its water quality, and that some management problems are common to both the grassy ecosystem sites and to the Lake itself.
We note the terms of reference for your investigation into the state of the water courses and catchments for Lake Burley Griffin including:
- possible improvements for managing water quality and the appropriateness of the current protocols for lake closures;
- identifying the causes of lower water quality, including possible resource implications of addressing them;
- jurisdictional implications for water quality management of the lake; and
- the implication of these findings for the ACT’s other major recreational waterways, such as Lake Ginninderra and Lake Tuggeranong.
However, we argue that the terms of reference are too narrow. The jurisdictional coordination challenge should apply to all management aspects, not only water quality. The inquiry should also consider adding additional terms of reference along the lines of:
- management of the Lake to benefit indigenous wildlife (particularly fish) and riparian vegetation to maximise biodiversity conservation;
- adaptive management of Scrivener Dam to enable continual environmental improvement and adaptation to climate change;
- implementation of the 2007 “ACT Aquatic Species and Riparian Zone Conservation Strategy”.
Our reasons for these additions are that we perceive a number of interlinked environmental problems with management of the Lake that require an integrated response, consistent with the measures recommended in the ACT Conservation Strategy but not yet implemented. For example, algal blooms are clearly a major issue in lake management due to excessive inflows of nutrients via the catchment and to poor Lake management. The advent of higher temperatures and changed hydrology with climate change will only exacerbate the problem. Policies for reduction of diffuse nutrient pollution (through riparian zone conservation for example) and greater use of artificial wetland filters are two key approaches that could help reduce algal blooms. Both riparian zone conservation around the Lake and grassland and grassy woodland conservation in the Molonglo River catchment can contribute to reducing nutrient inflows.
Another problem is that much of the shoreline of Lake Burley Griffin is now occupied by exotic deciduous plants. These species contribute to water quality problems through the mass deposition of leaves in autumn and offer poor habitat for indigenous fauna. Replacement of these exotic species with flora indigenous to riparian habitats in the ACT would assist in improving water quality, with the added benefit of providing better habitat for birds and aquatic fauna. In our view, the Lake should, as far as possible, be managed as habitat for indigenous biota, with weeds and pest animals discouraged.
The Lake environment is in a very poor ecological condition as an artificial dam that has not been adaptively managed to incorporate modern conservation measures. Some obvious measures that should be explored include addition of a fish ladder on Scrivener Dam to facilitate native fish migration and breeding, installation of a thermal pollution control device, cessation of stocking the Lake with non-native fish species. Removal of exotic vegetation along key sections of lakeshore is needed to enhance indigenous fauna habitats. Further, to desiccate Carp eggs and to encourage growth of aquatic vegetation the Lake's water levels should be varied to further enhance the Lake’s ecosystem.
Thank you for the opportunity to contribute to this inquiry. Further information on the comments in this submission can be provided by Dr Jamie Pittock.
John Fitz Gerald
27 July 2011