In Summary, the short term solution is to manage the blooms through treatments such as Phoslock and hydrogen peroxide. Unfortunately GCCC do not currently have equipment to treat with hydrogen peroxide. Computer modelling has indicated that the installation of Aerators would give the best result in reducing algal blooms.
Some Statements Taken from the Report
Our report does not provide any additional information on catchment management options because its purpose is to review and propose in-lake options for managing algal blooms. However, we note that ongoing evaluation of stormwater volumes and nutrient loads is required and that the success of these will determine the longevity of in-lake management options.
Conceptual models showing the state of the lake in 2008 (Management Plan), and a scenario of a transition to a eutrophic system highlighted the potential outcomes that could occur with continued excess nutrient inputs, such as algal blooms and fish kills. It is clear that some of the anticipated issues identified in 2008 have come to eventuate in 2018 and that more active management intervention actions are required.
Computer Modelling showing aeration giving the best result in Algae reduction. (green Line)
Water quality of Lake Hugh Muntz has deteriorated markedly over the past 15 years.
Once management actions are adopted at the whole lake scale, an idealised scientific approach of a single action followed by observation(s) is not generally possible or desirable, and the approach should be to adopt multiple management actions concurrently. For example, if a geoengineering material (Phoslock etc) was applied within the lake, then catchment management actions should be adopted concurrently, to maximise the durationon which the geoengineering treatment was effective.
In the shorter term, managing blooms using interventions within the lake is likely to be the most cost-effective option. Our lab analyses showed positive effects, both for the application of hydrogen peroxide and PhoslockTM but other chemicals (e.g., PAC) may have complementary effects related to additional inactivation of phosphorus.
It is important to note that the application of hydrogen peroxide is only an intermediate solution and will not solve the underlying cause of cyanobacteria blooms (i.e., the combination of high nutrients and the shallow freshwater lens in the lake). Simulation scenarios indicated that complete overturn of the water column through installation of a bottom aerator (i.e., artificial destratification) was the most effective remediation methodbut it is very expensive and would elevate nutrients and salinity in the surface water layer as well as maintaining particulate material in the water column for longer periods of time. This technique may result in little change in water quality although it would reduce the incidence of surface blooms.
For immediate action, we recommend:
initiating mesocosm experiments in the field, trialling the effectiveness of hydrogen peroxide and PhoslockTM under natural conditions. This will then demonstrate whether hydrogen peroxide is effective for C. ovalisporum at concentrations tested in the laboratory and minimising the effect on other algae and animals. Additionally, Phoslock trials will test how effectively the compounds reduces phosphorus concentrations in the water column, and caps the sediment.
water quality model runs to test adequate dosages and timing of application to avoid spending unnecessary resources and/or achieving sub-optimal results.
laboratory measurements to better understand the growth requirements and toxin production of C. ovalisporum isolated from Lake Hugh Muntz. This is a poorly studied species so the literature is not helpful for the modelling questions. Additionally, the isolates Lake Hugh Muntz will be locally adapted to specific salinity, temperature, light and other conditions. This information is crucial to effective modelling.
Have received information from Council that recent water quality testing undertaken within Lake Hugh Muntz has indicated an increase in Algae Biovolume. Council is currently testing the water on a weekly basis.
This information is in line with the current observations of reduced water clarity and the lake turning a green/brown colour. Will provide further updates on progress when received.
Great to see the recent rain but unfortunately this has washed soil into many areas of the lake on top of the recent Phoslock application. Soil together with leaves, lawn clippings etc added directly to the lake are only going to add nutrients to the water that feed the algae and reduce the effectiveness of this expensive application.
It is important that GCCC and residents accept responsibility and take action. Minimise any erosion of soil and lawn clippings entering the lake by ensuring adequate maintenance of lawn areas, mowing of lawns with catchers and erosion control measures to reduce this damage.
The Phoslock treatment of the lake is progressing and the even spread of the product is important to provide the best possible outcome for the lake. To ensure an even distribution, please adhere to the Councils signage and do not enter the water this weekend!
Some great news with a trial of Phoslock to begin next week! This trial will involve a whole lake treatment, not just a small trial area.This could not of come at a better time with the latest water quality results indicating an increase of algae in all areas with the lake possibly heading for closure in the near future.
Phoslock has been highlighted by Griffith Uni as one of the key products to offer possible improvements to the condition of LHM. It should be noted that due to many variable factors, there is no guarantee that this treatment will provide the desired results.
The treatment will involve the spreading of Phoslock to the surface of the lake by boat. The treatment will take time to settle to the bottom. As a result the lake will be closed all next week and signs will be erected notifying the public.
The challenge now is to implement an effective Management Plan to ensure that any improvements are maintained to provide long term improvements in water quality for the benefit of all lake users.
From experience, nothing every happens quickly in Council!
Council should be commended for getting this major treatment implemented before the next algae outbreak with special mention to Paul Taylor, Steven Mc Veigh and Darren Ford for getting this treatment over the line in a very short time fame.
After an incredibly long 9 months LHM is now open. Grab your swimmers and tell your friends to get down and enjoy this fantastic community asset while you can!
We are currently waiting on the release of the Long Term Options report due in September and more importantly what Council intend to implement and will advise when received.
Official statement from Council below;
As a major stakeholder in Lake Hugh Muntz, the City would like to advise you of the following;
Water quality sampling has confirmed that blue-green algae levels at Lake Hugh Muntz (LHM) have returned to acceptable levels in accordance with the National Guidelines.
Weekly water quality testing has confirmed that both the algae and toxin concentrations have declined and are no longer at a level where they pose a risk to public health.
Whilst the algal bloom has declined significantly, the species of algae that has persisted in LHM (Chrysosporum ovalisporum) is known to produce spores. These spores can often remain dormant in the sediment of a waterbody and become activated when weather conditions become favourable, especially during warmer temperatures. This may result in another algal bloom in the near future as temperatures increase during summer.
Whilst temporary warning signage has been removed from the lake, please continue to exercise caution and avoid contact with water:
where scums or floating debris are visible
that looks discoloured, murky or smells unpleasant
near stormwater drains
for up to three (3) days after heavy rainfall
if you have an open wound or infection
Routine water quality sampling will continue at LHM to monitor conditions. Should conditions change, further advice will be provided.
Council are currently testing a real time water quality monitoring system in Lake Hugh Muntz. If the unit can provide regular, consistent data over time, this will be invaluable in not only mapping changes in water quality, but in measuring the effectiveness of possible future solutions implemented.
The unit is currently installed in the West side of the lake which has some serious problems with no oxygen at depth and high nutrient levels. It is important that the unit is not disturbed so please keep clear!
“There is high uncertainty of a positive outcome for many options, time is required for engineering development (e.g., a boat designed to distribute hydrogen peroxide) in some cases and/or permits are required by State and Commonwealth authorities for discharge to the canal”
Council have confirmed, NO implementation regarding the Short Term Options.
With no action planned, a lot is dependent on the Long Term Options Report Due in 2 weeks!
Urgent action is required by Council to implement Long Term Options that are effective and in a timely manner preferably before the next bloom. Permanent damage as has already occurred with the loss of most, possibly all underwater aquatic plants. Any delays are going to increase difficulty, increase time frame and cost of lake restoration.
Without intervention, and with the rapid increase and severity of past algal blooms, the trend is for an even bigger bloom this year. No one can predict the outcome but the question has to be asked “are we heading for an ecological disaster”
Clearly the lake cannot enter a Third year of algal blooms without Action!