Recreational water qualityIndicator
Recreation water quality is poor in the ACT for both lakes and rivers. Nearly every monitored recreation site experienced closures due to the exceedance of enterococci guidelines, and blue-green algae has required extended closures in Canberra’s lakes. Lake Tuggeranong was closed for most of the 2018–19 recreational swim season due to poor recreational water quality.
Indicator assessment legend
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.
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
- Recreational water quality monitoring
- Blue-green algae
- Impacts of urban and rural run off
Recreational water quality refers to the suitability of water for swimming and other activities that involve direct contact with the water. Canberra’s lakes and rivers are important for providing amenity and opportunities for recreation. However, the use of lakes and rivers depends on having good recreational water quality.
Assessments of recreational water quality are based on the potentially harmful bacteria known as enterococci and blue-green algae (cyanobacteria). Enterococci, also known as faecal coliform bacteria, are not necessarily a problem for aquatic ecosystems, as they generally serve as food for aquatic organisms without causing them harm. However, the presence of high numbers of faecal coliforms can affect human health when recreational activities involve direct contact with the water. Ingestion of these bacterial pathogens can lead to gastrointestinal illnesses such as diarrhoea. Stormwater run-off is the main source of enterococci, with sewage overflows and releases from damaged pipes also potential sources.
Blue-green algae are naturally present in aquatic ecosystems, but under certain conditions their populations can increase causing a potentially toxic bloom. Low river flows, high temperatures and high levels of nutrients are the primary cause of blue-green algal blooms. Blue-green algae can produce toxins that are harmful to humans and animals when they are swallowed, inhaled, or come into direct contact with the skin. Reactions are variable, depending on the length and type of contact. Common symptoms include irritated skin, flu-like symptoms and gastrointestinal illness resulting in vomiting, diarrhoea, fever and headache.
Recreational water quality monitoring
Recreation water quality monitoring is undertaken in accordance with the ACT Guidelines for Recreational Water Quality across a total of 17 sites in Lake Ginninderra, Lake Tuggeranong and the Murrumbidgee, Paddys and Molonglo riversACT Health, 2014, ACT Guidelines for Recreational Water Quality, found at https://health.act.gov.au/about-our-health-system/population-health/environmental-monitoring/water-quality Recreational water quality is also assessed at 10 sites in Lake Burley Griffin by the National Capital Authority.National Capital Authority, 2019, Lake Burley Griffin 2018–2019 Recreational Season: Summary of Alerts and Closures, found at https://www.nca.gov.au/national-land/lake-burley-griffin-management/lake-water-quality Although the ACT Government is not responsible for the management of Lake Burley Griffin, this data is included because of the important amenity and recreational value of the lake to Canberrans.
Water samples are taken weekly during the recreational swimming season (between approximately October to April) for enterococci and throughout the year for blue-green algae. If samples for enterococci and blue-green algae exceed guideline levels, then a resample is obtained and tested. If two consecutive samples exceed guideline levels, then the site is closed for primary contact. Reopening a recreational site after a closure requires two samples within guideline levels.
Condition and trends
The ACT Recreational Water Guidelines were updated in October 2014 and the new exceedance levels were incorporated into monitoring from 2016–17. Due to this change, this report only includes data from 2016–17 onwards.
Results for enterococci monitoring over the 2016–17 to 2018–19 period for are shown in Figure W27. It is important to note that total closures are based on results for all monitored sites for each location. Closures for each site occur concurrently and so the data presented does not represent the actual period each location was closed to recreation over the swimming season.
The main trends are:
- nearly every monitored recreation site experienced closures due to the exceedance of enterococci guidelines.
- for lake recreation areas, Lake Ginninderra had the highest number of site closures for each year, although there were slight declines in enterococci closures over the reported period.
- Lake Ginninderra is the only lake where enterococci is the main cause of recreation closures.
- Lake Burley Griffin had the lowest total enterococci closures for Canberra’s lakes.
- the Murrumbidgee River had a high number of site closures for enterococci, but this is likely a reflection of the greater number of sites monitored in comparison to other recreation areas.
- enterococci results for Paddys River are a concern with substantial periods of closures for the single site monitored, including for 20 weeks in 2017–18 (the recreational swimming season is typically around 27 weeks), and
- all recreational closures for the Murrumbidgee River and Paddys River were due to enterococci.
Figure W27: Total weeks of site closures due to exceedance of enterococci guidelines over the recreational season (October to April), 2016–17 to 2018–19. The number of sites monitored is shown for each recreation area.
Results for blue-green algae monitoring over the 2016–17 to 2018–19 period for are shown in Figure W28. The main trends are:
- the principal reason for recreation closures for Lake Tuggeranong and Lake Burley Griffin is blue-green algae.
- Lake Tuggeranong had the highest number of blue-green algae closures in 2016–17 and 2018–19, and Lake Burley Griffin for 2017–18.
- Lake Tuggeranong was closed for most of the 2018–19 recreational swim season due to severe blue-green algal blooms.
- There were no closures due to blue-green algae for Lake Burley Griffin in 2016–17, and
- the Molonglo River was the only river to have recreation closures due to blue-green algae.
Figure W28: Total weeks of site closures for exceedance of cyanobacteria guidelines, 2016–17 to 2018–19. The number of sites monitored is shown for each recreation area.
Impacts of urban and rural run-off on recreational water quality
The high number of recreational site closures due to enterococci shows that urban and rural run-off is depositing high levels of this bacteria into the ACT’s lakes and waterways. To reduce the number and duration of 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 (see Case study – Expert commentary: Water quality in the ACT).
Urban and rural run-off is also the main driver of recreation closures due to blue-green algae. Rainfall run-off transports high amounts of nutrients into lakes and other waterways enabling algal blooms to occur. Consequently, improved run-off management and interception is key to reducing algal blooms in Canberra’s lakes. However, the occurrence of algal blooms is also driven by climate factors such as extended dry periods and hotter temperatures. With these conditions set to increase as a result of climate change (see Indicator CC1: Climate trends), reducing the amount of nutrients in waterways will be required to prevent longer and more frequent recreation closures in the future. The prevention of blue-green algae blooms will not only increase the amenity of the ACT’s lakes and waterways, but will also prevent potential impacts on aquatic ecosystems such as fish kills.