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Lake Hugh Muntz - water quality project

Algal blooms are not unique to Lake Hugh Muntz. Many urban lakes in south east Queensland and across the world, particularly those fed by nutrient rich stormwater runoff, experience changes in water quality resulting in algal blooms.

Every lake has individual characteristics, inputs and issues. The irregular shape, variable depths (from 4 to 12 metres), and volume of water (equivalent to 280 Olympic sized swimming pools) within Lake Hugh Muntz make it challenging to resolve the issues that have led to outbreaks of blue-green algae. A number of other factors including stormwater inflows, urban run-off, the age of the lake, climate, salinity changes, and groundwater input also contribute to water quality.

Considering these challenges, in 2018 City of Gold Coast engaged Griffith University’s Australian Rivers Institute to investigate feasible options for reducing future algal blooms. The University’s experts in lake management have been engaged in the following program of works:

Stage 1

In 2018 the University researched 20 potential management options previously used in Australia and around the world and advised on options likely to work best for Lake Hugh Muntz. Many of these options were found to be impractical, of no benefit, not recommended, or requiring further testing.

Read the Griffith University report.

Stage 2

  • December 2018 - Trial of Phoslock®, a modified bentonite clay that works by binding the nutrients which the algae require to grow. Phoslock has been used extensively 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.
  • Additional landscaping and park works were also carried out to help reduce sediment runoff into lake and the footpath from the Bel Air Carpark to the lake was widened to reduce edge erosion.

Stage 3 (ongoing)

  • In 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, salinities, and whether it can be used in conjunction with sand capping. March 2020 - Model the effectiveness of different long-term management options using experiment and water quality data.

Griffith University is due to report back to the City about these current and ongoing investigations in mid 2020. Once the Griffith University report has been received, the City will conduct a multi-criteria assessment of any recommendations made to inform the future management of the lake.

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