Forest Lake management plan

Council is implementing long-term solutions as part of the Forest Lake management plan to improve the health of Forest Lake for the community and the environment.

Brisbane’s natural environment makes our city one of Australia’s best places to live, work and relax. It’s important that we continue to work together to protect our waterways to ensure future generations can enjoy them.

Council is implementing a long-term plan to combat the ongoing issues affecting Forest Lake.

This program is in addition to a range of other measures Council is undertaking to improve the health of Forest Lake.

Summary

This table provides summary information about the Forest Lake management plan including address, ward, project outcomes and latest update.
Address The Lake Parklands, Forest Lake
Ward Forest Lake
Project outcomes To reduce algal blooms in Forest Lake and improve the health of the lake ecosystem
Latest update New staged approach for project works

Project background

A number of environmental issues have affected the lake over the last few years including:

  • high nutrient levels in the lake have led to blooms of algae. Blue-green algae growth, in particular, can cause skin and eye irritations for people and pets touching the water, as well as emitting a strong, musty odour.
  • rapid growth and coverage of the waterweed, Salvinia. The plant can die off and sink to the bottom of the lake, reducing dissolved oxygen levels, meaning that there isn't as much oxygen for fish and aquatic species to breathe.
  • the ibis population increasing on Bird Island and other areas around the lake, resulting in odour issues and high nutrient levels in the lake.

There is no one quick fix to solve these environmental issues at this man-made lake. Improving the health of the lake ecosystem will need a range of solutions and will take time.

Council activities at the lake

Much has already been done to improve the lake's health and the benefits can be seen in the improvement of the lake's general water quality and reduction in algae blooms. This includes:

  • managing the ibis through egg and nest management, and by removing specific vegetation types to deter ibis from the lake. The number of ibises roosting at Forest Lake has been regularly monitored. In June 2020, there were 122 birds. This is a decrease from the highest counts of ibis at approximately 469 in January 2018 and 440 in July 2018, demonstrating an effective reduction in the number of ibis at Forest Lake. Overall, this will benefit the health of the lake by decreasing the unwanted nutrients they bring to the lake through their droppings.
  • the Salvinia harvesting works at the lake. The Salvinia has provided an interim solution to reducing the high nutrient levels that have contributed to algae growth in the lake until the native plants are established in the lake in late 2020 and mid-2021. Council will continue to actively manage the Salvinia to help reduce nutrient levels in the lake, while still minimising its cover across the lake.
  • rehabilitation works near Seabrook Crescent have been completed, which included desilting the inlet, minor tree removal, and revegetation work. This improves hydraulic drainage of the creek and has reengaged the original silt traps.
  • tree and vegetation management in the lake parklands. Council has removed some trees that had died and or leaning over private property. Over 100 trees will be planted in the next year. Some of these will be located around the lake to help shade and cool the water, and others will be planted in the park area.

General maintenance and routine inspections will continue at the lake, which will include:

  • continuing the successful ibis management plan
  • testing and analysis of the lake water quality (which allows Council to implement appropriate actions where required)
  • treating weeds around the lake
  • collecting litter
  • clearing traps
  • monitoring and managing any changes to the lake environment.

Project works

To find the best solution for the lake, the expert working group divided lake management options into four categories:

  • reducing nutrient levels (both those entering the lake and those already in the lake)
  • managing light availability
  • recreating a more 'plant-based' lake system
  • potentially increasing water movement in the lake.

Additional monitoring is proposed to address key data gaps over time and continue to adapt the management of the lake.

The Forest Lake Strategic Management plan recommends strategic desilting at the two inlet areas of the lake to reduce nutrient loads where the sediment deposition and nutrient levels are highest.

The purpose of this stage is to rectify the nutrient levels in the lake which are contributing to the algal blooms. It also recommends replanting in the desilted area and more broadly across the lake to help reduce the nutrient levels in the lake.

While these measures are being introduced and until ecosystem health improves, the lake may see further occurrences of algal blooms and Salvinia growth.

While these measures are being introduced and until the ecosystem's health improves, the lake may see further occurrences of algal blooms and Salvinia growth.

New staged approach

Since the release of the plan, Council has been investigating and planning the project works. This process has taken longer than originally anticipated due to the complexity of the project, however, early works undertaken in and around the lake have already been implemented.

Council is committed to providing the best possible outcome for the lake and in doing so must prioritise the timing of the desilting and planting works for this project. Due to the extended timeframes, Council will be undertaking a new staged approach (developed by the expert working group) to desilting and planing works at the lake.

As timing of works is critical to their success, desilting has been moved to mid-2021 to avoid undertaking works during the upcoming summer storm season. This will reduce the risk of works being washed out and sediment flowing from the works area into the open lake. Weather permitting, this will allow the new plants in the desilted area time to establish before the 2021-22 summer storm season.

Ultimately, timing the works in this way will provide the best outcome for the health of the lake. It will also provide interim health benefits to the lake with an additional planting exercise later this year, while ensuring desilting and replanting is undertaken at the most suitable periods.

Download the latest project newsletter in your preferred format:

Timing

This 3-part timeline shows the new staged approach.

Council is committed to keeping the community informed of the project works and will provide advance notification of each stage.

Stage

Planting

LATE 2020

Planting at this stage will include areas where desilting will not occur. These plants will improve the health of the lake during the summer months by reducing the nutrient levels available for algae to grow.

Stage

Desilting

MID-2021

This work will take place in two inlet areas of the lake to reduce the sediment loads and levels of nitrogen and phosphorus available for algae growth. Council has applied for the Queensland Government permit required to undertaken the desilting works in this environment.

Stage

Additional planting

MID-2021

More planting following the desilting in mid-2021 to recreate a more 'plant' based lake system.

Expert working group

Due to the complexity of the health issues impacting Forest Lake, Council established a dedicated expert working group in April 2019. This group is made up of Council scientists and external water experts to ensure that any future works undertaken are based on the best expert advice.

Supporting Councils experts are Professor David Hamilton who is the Deputy Director of the Australian Rivers Institute, Griffith University and Tony Weber who is one of Australia's leading practitioners in catchment modelling and water quality.

Strategic management plan

The Forest Lake Strategic Management Plan has been developed by the expert working group and outlines the best evidence-based solutions to improve the long-term health of Forest Lake.

Download the strategic plan in your preferred format:

Findings from earlier investigation works

Council undertook investigations on the lake via boats and sampling equipment in March 2019.  By sampling at different depths throughout the water column, these important investigations provided a more in-depth understanding of water quality. 

You can find a copy of the report within the Forest Lake Strategic Management Plan.

Get involved

Council has received some interest from the community to form a new Habitat Brisbane group in Forest Lake. The Habitat Brisbane Program provides an opportunity for the local community to work with Council to protect and enhance the habitat values of local parks and natural areas.

A new group is in the early stages of formation and will be working at Hancock Park.

Although not directly located on the lake, Hancock Park has bushland registered as remnant native vegetation and is a strategic corridor linking Commonwealth lands at Wacol through Forest Lake and to Heathwood bushland, and more broadly is a significant connection between the Greenbank Military Training area to Karawatha Forest, Parkinson/Larapinta bushland and Richmond via Bullock Head Creek, with run-off into Forest Lake.

If you’re passionate about the environment and are keen to make a difference with hands-on volunteering or would like to learn more, phone Council on 07 3403 8888 or email the project team.

Register for updates

Register for updates on the Forest Lake management plan.

More information

For more information:

  • email the project team
  • phone the project team on 1800 669 416 (during business hours)
  • phone Council's Contact Centre on 07 3403 8888 (after hours).
  • write to:
    Forest Lake management plan project
    City Projects
    Brisbane City Council
    GPO Box 1434
    Brisbane Qld 4001.
Last updated:30 July 2020