The NCA's water quality program comprises three sub-programs to monitor the overall environment of the Lake as well as the bacterial quality and algal conditions during specific periods at specific sites (to support the recreational use of the Lake).
These sub-programs are summarised below.
A brief summary of the testing program is also discussed below.
Routine Testing of Midstream Samples
This is a monitoring program to determine how the water quality of the Lake is performing against management benchmarks and established long-term trends, as well as to report on the overall environmental condition of the Lake.
Under this program, water quality conditions are assessed and reported (usually on a monthly basis excluding April, June, July and September), using midstream samples from four sites (five sites from April 2009) within the Lake. A wide range of physical, chemical, microbiological and biological analyses are carried out at these points to determine the overall water quality at these sites. These analyses then allow judgements to be made about overall water quality right across the Lake. The concentration of bioavailable nutrients at the end of the mixing period provides an indication of the potential for primary production the following summer. Where possible, inclusion of oxidation-reduction potential to the suite of temperature, dissolved oxygen, conductivity, pH and turbidity is recommended.
The results are analysed annually and compared with historical data and the benchmark values of this WQMP. Assessments of the trends of selected water quality indicators are also carried out to identify an improvement or a deterioration in water quality.
- Routine lake monitoring by boat (eight sampling events, commencing August).
Routine water quality testing, assessment and reporting is carried out by ECOWISE Australia Pty Ltd, trading as ALS Water Resources Group. The routine monitoring of Lake Burley Griffin water quality began in December 1981. It has been continued, with a few modifications, to the present day by ECOWISE Australia Pty Ltd, trading as ALS Water Resources Group (with the exception of the 1998–99 period when monitoring was undertaken by the University of Canberra).
Microbiological Monitoring of Designated Recreational Sites
This is a program carried out during a specific period at specific sites from a public health and safety viewpoint to support the recreational use of the Lake.
Under this program, bacterial quality of the water is tested in accordance with water quality guidelines. The sites are tested periodically (not more than seven days apart) for the levels of intestinal enterococci in the water.
- Routine bacterial monitoring of beaches (weekly between the second week of October and the mid week in April).
Beach sites are monitored routinely between the second week of October and the mid week in April for microbial indicators of water quality contamination. This part of the program is designed to keep lake users informed of the health risks associated with the primary or secondary contact water activities permitted in those areas.
The ACT Health Protection Service also undertakes some monitoring of the upper reaches of the Lake, again associated with establishing the health risks for users of those parts of the Lake. The outcomes of the monitoring programs are managed separately and are outside the scope of this program.
There is also a need for increased monitoring should sewage spills occur and reduction in potential health risks requires the collaborative efforts and notifications of all agencies. Testing should be for reliable indicators of the potential presence of pathogens. The use of intestinal enterococci as an indicator is recommended by the Australian Government (2008).
Algal Monitoring Program
This is also a program carried out from a public health and safety viewpoint to support the visual and recreational use of the Lake.
This activity is part of the ACT-wide program to test and report on algal levels. Visual observation and laboratory testing for algae are carried out routinely in selected locations and actions are taken in accordance with the ACT Guidelines for Recreational Water Quality (ACT Government, 2010). Reliance on visual observation for the presence of potential toxin-producing cyanobacteria, which normally form blooms below the surface, is not recommended. The testing for both cell and toxin concentrations is recommended as this is a more reliable assessment of human health risk.
The NCA reserves the right to undertake or support ACT Government authorities in additional:
- events based tests;
- stormwater monitoring, sampling variability investigation;
- pathogenic free-living protozoans survey (when water temperatures are high or following sewage spills or treatment plant malfunctions in summer);
- investigate sources of faecal contamination if the above is recorded;
- monitoring of hypolimnetic concentrations of nutrients, particularly the bioavailable forms of ammonia/ammonium nitrogen, oxidized nitrogen and soluble reactive phosphorus when the water column is stratified.
- additional monitoring as required by the NCA during the swimming season.
The NCA undertakes to conduct periodic Sanitary Surveys to identify changes in source of faecal contamination.
Routine water samples are collected from a tube sampler, being 5 metres in depth (where depth is sufficient). Bacterial samples are collected 0.3 m below the water surface by ‘grab sampling' directly into the final sample bottle. Detailed information on the exact method of sampling is contained in Appendix A.
General Management Response
Decisions to issue warnings or close the Lake are based on a series of test results (five tests) taken over a period of time not exceeding 5 days. Management actions should be based on the ACT Guidelines for Recreational Water Quality (ACT Government, 2010).
The NCA's management response generally includes routine communications with regulatory agencies including the ACT Environment and Sustainable Development Directorate's Environment Protection Authority and ACT Health Protection Service, and also the transfer of data, consultation and formulation of management actions. In case of contamination, the NCA consults with the regulatory agencies to ensure an immediate response and appropriate regulatory action.
If a closure is recommended, this is coordinated with the ACT Water Police in consultation with commercial operators and event organisers, with warning signs informing the public erected at the affected sites.
Wherever necessary, the NCA's communication strategies include appropriate public announcements, media statements, interviews, Lake Closure notices, regular update of the NCA's website, and Lake signage of the current water quality condition.
Detailed discussions of the management responses are covered in the following sections.
General Catchment Management Issues
The catchment of Lake Burley Griffin covers parts of NSW and the ACT. Consequently, there is a significant catchment management role played by:
- NSW state government agencies and departments such as the NSW Government Office of Water;
- NSW local governments such as the Queanbeyan City Council;
- ACT government agencies and departments such as the Environment and Sustainable Development Directorate and other sections of the Territory and Municipal Services Directorate; and
- Community organisations comprising Landcare and catchment management interest groups such as the Molonglo Catchment Coordination Group.
This Plan also supports good land management practices in catchments, adhering to relevant environmental policies aiming at nutrient reductions, sediment control and pollution removal. Management of stormwater quality is critical to the maintenance of lake water quality. In this respect, the catchment management roles played by the agencies stated above contribute to achieving good water quality in the Lake.
In terms of the above-mentioned organisations, the ACT Environment and Sustainable Development Directorate provides a key water management role and has produced a range of documents relevant to this WQMP, including:
- ACT Government (2011). ACT Water Report 2009-2010.
- ACT Government (2004). Think water, act water, Volumes 1, 2, and 3.
- ACT Government (2006) Environmental Flow Guidelines.
The ACT Health Protection Service has produced the local recreational water quality guidelines relevant to this WQMP: