Indicator assessment
CONDITION
TREND
DATA QUALITY
Recreational water quality is poor in the ACT for both lakes and rivers. All of Canberra’s lakes experienced closures in every recreational season due to the exceedance of enterococci and/or blue-green algae guidelines. Lake Tuggeranong has by far the most closures, regularly suffering from cyanobacterial blooms and high levels of faecal contamination. These are often accompanied by odours and highly turbid water, reducing the recreational and aesthetic value of the lake and surrounds. The 2022–23 recreational season had the highest total closures across the ACT since 2015–16, with Lake Tuggeranong closed for 80% of the recreational season. The Murrumbidgee, Cotter, and Paddys rivers experience closures in every recreation season due to high enterococci concentrations.
CONDITION
Environmental condition is healthy across the ACT, OR pressure likely to have negligible impact on environmental condition/human health.
Environmental condition is neither positive or negative and may be variable across the ACT, OR pressure likely to have limited impact on environmental condition/human health.
Environmental condition is under significant stress, OR pressure likely to have significant impact on environmental condition/ human health.
Data is insufficient to make an assessment of status and trends.
TREND
DATA QUALITY
Adequate high-quality evidence and high level of consensus.
Limited evidence or limited consensus.
Evidence and consensus too low to make an assessment.
Assessments of status, trends and data quality are not appropriate for the indicator.
Introduction
For information on this indicator, including the assessment of recreational water quality in the ACT, see Background: Water.
Recreational water quality results show that the ACT often experiences substantial recreational site closures, although this can be highly variable between lakes and rivers, recreational seasons, and even between sites within a waterbody. Ongoing occurrences of recreational site closures mean that urban and rural rainfall run-off continues to deposit high levels of bacteria and nutrients into the ACT’s lakes and waterways. To reduce the number and duration of recreational closures, there needs to be improved run-off management and interception in urban areas and the re-establishment of riparian vegetation in both urban and rural areas.
The occurrence of cyanobacteria blooms is also driven by climate factors such as extended dry periods and hotter temperatures. With these conditions projected to increase in the future (see Climate change), reducing the amount of nutrients in waterways will be required to prevent longer and more frequent algal blooms and recreation closures in the future.
Canberra’s lakes
There is much variability in the total recreational season closures between Canberra’s urban lakes (Figure 23). For the recreational seasons from 2015–16 to 2022–23, Lake Tuggeranong had by far the most closures, with Lake Burley Griffin having the fewest closures for all but one season. Recreational closures for Lake Ginninderra were generally much lower than for Lake Tuggeranong, but similar to Lake Burley Griffin between 2018–19 and 2021–22. The 2022–23 recreational season had the highest total closures across the ACT since 2015–16.
Figure 23: Proportion of the recreational season that Canberra lakes were closed to recreational activities, 2015–16 to 2022–23.
Data sourced from: Environment, Planning and Sustainable Development Directorate. Lake Burley Griffin data from the National Capital Authority.
Notes: Data shows the average closures across monitored sites during the recreation season (around mid-October to mid-April), including for Lake Tuggeranong (5 sites), Lake Ginninderra (4 sites), and Lake Burley Griffin (8 sites).
Lake Tuggeranong
Lake Tuggeranong was frequently closed over the eight recreational swimming seasons from 2015–16 to 2022–23 (Figure 24). In six of those seasons, the lake was closed for around 60% or higher of the recreational season. In 2022–23, the lake was closed for nearly 80% of the recreational season, the highest closures since 2015–16. The high frequency of recreational closures for Lake Tuggeranong are likely due to its small size in comparison to its catchment area, combined with high inputs of nutrients and enterococci bacteria from rainfall runoff.
Figure 24: Proportion of the recreational season that Lake Tuggeranong was closed to recreational activities by closure reason, 2015–16 to 2022–23.
Data sourced from: Environment, Planning and Sustainable Development Directorate.
Notes: Data show the average closures across five monitored sites during the recreation season (around mid-October to mid-April). Recreational closure data is only available for Lake Tuggeranong from 2015–16.
Most of the recreational closures are caused by high concentrations of cyanobacteria in the lake. Although closures also occurred in each season because of the high levels of enterococci, this includes 2022–23 when enterococci was responsible for most of the recreational closures.
The frequent recreational closures in Lake Tuggeranong clearly demonstrate a failure to meet the community’s recreational and aesthetic expectations for the lake. The prolonged closures prevent community access to Lake Tuggeranong for a range of summer water activities that involve primary contact. In addition, the loss of amenity, including strong odours and aesthetic impacts caused by algal blooms, have consequences for community health and wellbeing.
More extensive information on recreational water quality in Lake Tuggeranong, including reasons for water quality issues, can be found in the 2022 Investigation into the State of the Lakes and Waterways in the ACT.
Lake Ginninderra
Although the number of closures for Lake Ginninderra was highly variable over the eight recreational swimming seasons from 2015–16 to 2022–23, closures occurred for around 20% or more of each recreational season (Figure 25). The highest number of closures occurred in 2022–23 when the lake was closed for nearly 60% of the recreational season.
Figure 25: Proportion of the recreational season that Lake Ginninderra was closed to recreational activities by closure reason, 2015–16 to 2022–23.
Data sourced from: Environment, Planning and Sustainable Development Directorate.
Notes: Data show the average closures across four monitored sites during the recreation season (around mid-October to mid-April). Recreational water quality Recreation water quality is only available from 2015–16 for Lake Ginninderra.
High enterococci concentrations have been responsible for most of Lake Ginninderra’s recreational season closures, occurring in every season since 2015–16. This contrasts with recreational closures for Lake Tuggeranong and Lake Burley Griffin which experience more frequent periods of high cyanobacteria concentrations. The 2016–17, 2017–18, and 2022–23 seasons were the only years where cyanobacteria had a significant impact on recreational usage. It is not clear why there were high levels of cyanobacteria in these years. It is thought that the recreational water quality results for Lake Ginninderra may be influenced by the location of sampling sites. Some of the sampling sites are known to be key congregation points for ducks and other waterbirds which may be causing high enterococci levels. This requires further investigation.
More extensive information on recreational water quality in Lake Ginninderra, including reasons for water quality issues, can be found in the 2022 Investigation into the State of the Lakes and Waterways in the ACT.
Lake Burley Griffin
Recreation water quality monitoring results for the period 2011–12 to 2022–23 show that prior to 2020–21, Lake Burley Griffin was generally open for around 80% to over 90% of the recreation season (Figure 26). From 2020–21 to 2022–23, the lake was closed to primary contact for at least 25% of the recreational season, with 2020–21 closed for more than 30% of the season, the highest recreational closures since 2011–12. The increase in recreational closures may be from the high levels of rainfall runoff increasing concentrations of nutrients and bacteria in the lake. Despite the increased recreation closures in recent years, Lake Burley Griffin generally has fewer recreational closures than Lake Tuggeranong and Lake Ginninderra.
Figure 26: Proportion of the lake Burley Griffin recreation season closed to recreational activities, 2011–12 to 2022–23.
Data sourced from: National Capital Authority.
Notes: Data shows the average closures across eight monitored sites during the recreation season (around mid-October to mid-April).
The cause of recreational closures in Lake Burley Griffin have been highly variable with no clear reasons for the differences. For recent high rainfall years, cyanobacteria caused most of the recreational closures in 2020–21, but in 2021–22 and 2022–23, enterococci was the main cause of closures. Over the dry period from 2017–18 to 2019–20, most closures were for cyanobacteria, but in 2019–20, enterococci caused slightly more closures. Improved knowledge on the causes of recreational closures in Lake Burley Griffin is required to improve recreational water quality.
More extensive information on recreational water quality in Lake Burley Griffin, including reasons for water quality issues, can be found in the 2022 Investigation into the State of the Lakes and Waterways in the ACT.
ACT rivers
Over the eight recreational swimming seasons from 2015–16 to 2022–23, all of the monitored river recreation areas for the Murrumbidgee, Cotter and Paddys rivers experienced closures in every recreation season (Figure 27). All of the closures were the result of high enterococci concentrations.
Figure 27: Proportion of the recreation season closed to recreational activities for monitored ACT rivers, 2015–16 to 2022–23.
Data sourced from: Environment, Planning and Sustainable Development Directorate.
Notes: Data shows the average closures across monitored sites during the recreation season (around mid-October to mid-April), including for the Murrumbidgee River (7 sites), the Cotter River (1 site) and the Paddys River (1 site).
The Paddys River had the highest number of closures from 2015–16 to 2022–23 with five seasons having around 50% or higher of the recreational season closed, and only one season having less than 30% of the recreational season closed. The poor recreational water quality results for the Paddys River are a concern with substantial periods of closures for the single site monitored.
The Cotter and Murrumbidgee rivers typically have fewer recreational closures but do experience periods of poor recreational water quality. Between 2020–21 and 2022–23, the Murrumbidgee River had between 20% and 30% of the recreational season closed and the Cotter River had around 20% of the recreational season closed for two seasons.
Recreational water quality is also assessed for the Molonglo River immediately upstream of Lake Burley Griffin. Recreational water monitoring results from 2015–16 to 2022–23 show that the Molonglo River had few closures, typically around 10% or less of the recreation season, with five years having closures of 5% or less of the recreation season. Cyanobacteria is rarely the cause of closures, only occurring in 2018–19. The location and character of the Molonglo River recreation area is very different from the ACT’s other monitored river recreation areas and is also downstream of the Queanbeyan Sewage Treatment Plant. Consequently, it is not possible to compare results for the Molonglo River with the other assessed river recreation sites.
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