Lake Hugh Muntz – water quality project

• Project typeOcean, beaches & waterways
• Project schedule2018 onwards
• Contractor nameGriffith University

We have engaged Griffith University's Australian Rivers Institute to investigate feasible options for reducing future algal blooms at Lake Hugh Muntz and across the city's urban lakes.

Water quality at Lake Hugh Muntz

Algal blooms are not unique to Lake Hugh Muntz. Like many urban lakes in south east Queensland and across the world, it is fed by nutrient-rich stormwater runoff. This can cause changes in water quality resulting in algal blooms.

The lake has a number of challenging characteristics which have led to outbreaks of blue-green algae:

• the irregular shape
• variable depths (from 4 to 12 metres)
• volume of water (equivalent to 280 Olympic sized swimming pools).

Other factors contributing to water quality include:

• stormwater inflows
• urban run-off
• the age of the lake
• climate
• salinity changes
• groundwater input.

Investigating options to reduce algal blooms

In 2018 we engaged Griffith University's Australian Rivers Institute to investigate feasible options for reducing future algal blooms.

The University's experts in lake management have undertaken several programs of work.

Stage 1, 2018

In 2018, the University:

• researched 20 potential management options used in Australia and around the world
• provided advice about options likely to work best for Lake Hugh Muntz.

Read Griffith University's reports for Stage 1:

Study of Management Options to Mitigate Algal Blooms in Lake Hugh Muntz (2018)(PDF, 9MB)
Evaluation of Management Options for Lake Hugh Muntz (2018)(PDF, 775KB)

Following review, many of these options were found to be impractical, of no benefit, not recommended, or requiring further testing.

Stage 2, 2018–19

Activities undertaken include:

• A trial of Phoslock®. This modified bentonite clay works by binding the nutrients which the algae require to grow. Phoslock® has been used around Australia and the world, having been successfully applied to over 400 water bodies. The effectiveness of the Phoslock® trial is continuing to be measured and assessed.
• Landscaping and park works were carried out to reduce sediment runoff into lake.
• The footpath from the Bel Air Carpark to the lake was widened to reduce edge erosion.

Read the Griffith University 2019 Phoslock® Trial report(PDF, 645KB)

Stage 3, 2019 – ongoing

• September 2019: the University began investigations to determine whether a trial to 'cap' the bottom of the lake with clean sand could be effective. 'Sand capping' aims to reduce the leaching of nutrients from decaying material that has built up on the lake floor over the last three decades.
• November 2019: experiments to determine how phosphorus levels affect blue green algae.
• January 2020: additional Phoslock® experiments were undertaken to ascertain its effectiveness at different dosages, salinity levels, and whether it can be used in conjunction with sand capping.
• March 2020: work to model the effectiveness of different long-term management options using experiment and water quality data.
• September 2020: Griffith University provided their report with information gathered during the activities undertaken in Stage 3.

Read the Griffith University Report from Stage 3:
Trial study on reducing frequency and duration of cyanobacteria blooms in Lake Hugh Muntz (2020)(PDF, 3MB)

Work on this project will continue and we will continue to work with researchers from Griffith University.

Multi Criteria Assessment

We engaged Alluvium Consulting Australia to conduct an analysis of potential management options for the lake arising from the work undertaken by the Australian Rivers Institute.

Lake Hugh Muntz: Multi criteria analysis of available management options (2021)(PDF, 3MB)