Project Updates

Stay up to date on the review of Freshwater Lake.

Three options for Freshwater Lake

  • Option 1 - Existing system

    Maintain the lake in its current form and continue with existing maintenance and management practices.

  • Option 2A - Off-line treatment

    Maintain the lake in its current form with structural & management improvements to permanently enhance lake performance and quality, operations, and management.

    This option involves off-line water treatment where water is circulated out of the lake into a bioretention system and treated using a filter media, plants, and other biological processes external to the lake water body and then the water is recirculated back into the lake.

    Possible methods: biofiltration system or connection to wetlands.

  • Option 2B - In-line treatment

    Maintain the lake in its current form with structural and management improvements to permanently enhance lake performance and quality, operations, and management.

    This option involves in-line water treatment where water is treated in the lake using plants and other biological processes in a wetland/reedbed system within the lake.

    Possible methods: floating wetlands and reedbeds in Freshwater Lake.

How do the options compare?

We have summarised the technical reports to compare the options. Table 1 below provides a comparison of options against the principles and Table 2 looks at the similarities and differences between the options. For further details refer to the technical reports located in the document library on this page.

Table 1

Table 1: Comparison of options against principles
Future OptionReset lake water qualityRemove carp and enhance biodiversityRemove sludgeSecure and maintain water supplyReduce water lossesImprove water circulation and increase lake water turn overDevelop an effective and sustainable water quality treatment process
Option 1: Existing systemYESYESYESYESNONONO
Option 2A: Off-line treatmentYESYESYESYESYESYESYES
Option 2B: In-line treatmentYESYESYESYESYESYESYES

Table 2

Table 2: Side-by-side comparison of options
ConsiderationsActionsOption 1
Existing system		Option 2A
Off-line treatment		Option 2B
In-line treatment
Water qualityOptimises water quality and water turnoverNOYESYES
Water circulationImproves water circulationNOYESYES
Water conservationReduces water lossNOYESYES
Sludge removal frequencyReduces need to drain and remove sludge from the lakeNOYESYES
Sludge removal intervalYears before sludge removal may be needed again5-10 years20-30 years10-15 years
Biodiversity
Improves aquatic habitatNOYESYES
BiodiversityMay increase numbers of birds on site including ibisNONOYES
BiodiversityRemoves carpYESYESYES
BiodiversityKeeps existing desired flora and fauna such as turtles and waterliliesYESYESYES
Changes to water viewsMaintains existing open water views of the lakeYESYESNO
Changes to water viewsOffers a mix of wetland and open water views of the lakeNONOYES
Changes to water viewsMay obscure or block current water view from some propertiesNONOYES
Appearance of lake environsChanges the look of the lake by introducing either reedbeds or floating wetlandsNONOYES
Protection of plantings during establishment periodPlants will be protected by netting for 12-18 months to prevent grazing by birds during establishmentNot requiredNot requiredYES
Energy efficiencyImproved energy efficiencyNOYESYES
Lake managementReactive management of water qualityYESNONO
Lake managementPlanned and proactive management of water qualityNOYESYES
On-site works requiredOn-site works (e.g. install pipework, drain lake, remove sludge and carp)YESYESYES
Equivalent annual costs averaged over 30 yearsCosted on WGA report only using 2022 costs$421,800 average pa
$366,400 average pa
$377,900 average pa

Principles for Freshwater Lake

Seven principles apply to the options for the lake:

  1. 'Reset' lake water quality
  2. Remove carp and enhance biodiversity
  3. Remove sludge
  4. Secure and maintain water supply
  5. Reduce water losses
  6. Improve water circulation and increase lake water turn over
  7. Develop an effective and sustainable water quality treatment process