Forest Lake management plan | Brisbane City Council

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 will inject more than $1 million over two-and-a-half years to implement 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.


Address The Lake Parklands, Forest Lake
Ward Forest Lake
Project outcomes To reduce algal blooms on Forest Lake and improve the health of the lake ecosystem
Latest update

Project commenced February 2019

Council is currently completing investigations on the lake. Find out more

Project background

The lake at Forest Lake is a man-made wetland that was originally designed as a stormwater quality improvement device to:

  • improve water quality flowing into the downstream creek system (Oxley Creek)
  • provide recreational and visual amenity for the community.

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

  • algal blooms causing the lake to be closed to recreation, as well as creating visual and odour issues
  • extensive blooms of the water weed salvinia have required mechanical removal on the lake surface
  • fish kills of the pest fish species tilapia and small numbers of native catfish
  • a rapidly growing ibis population, causing visual and amenity issues at the lake.

Algal blooms

Algal blooms have been a primary cause for concern at the lake. They are also a challenge facing many water bodies nationwide.

The four main factors that come together to create the perfect environment for algal blooms to thrive are:

  • high light levels
  • high nutrient levels
  • high temperatures
  • layers of different water temperatures within a lake (stratification).

Council has been conducting water quality monitoring at Forest Lake since the first major algae blooms in 2011/12. We've recently reviewed the condition of the lake, including water quality and historic events contributing to environmental issues at the lake.

The findings suggest that at Forest Lake conditions are ideal for algal growth due to a number of factors including:

  • sediment and nutrient inputs from big floods like the one caused by Cyclone Debbie in 2017
  • nutrients and sediments flowing into the lake from residential stormwater runoff
  • build-up of sediment at the bottom of the lake over 24 years
  • hot summer weather
  • lack of water flow within the lake
  • changes in the lake dynamics, such as a reduction in water plants.

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.

About the project

A two-and-a-half-year program is underway to improve the health of Forest Lake. This includes the following measures to reduce sediment and nutrient levels in the lake and enhance water movement – key elements in reducing the conditions that support algal blooms.

  1. The design and implementation of water aeration and circulation devices.
  2. Desilting the lake to remove large volumes of sediment and nutrient loads that have built-up over time.
  3. Development of a strategic management plan for the long-term management of the lake.

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

This new program of activities will be undertaken in addition to Council’s existing efforts to manage Forest Lake including:

  • an ibis management program
  • salvinia weed harvesting
  • cleaning litter out of litter traps upstream of the lake.

Ibis population

Ibis are an Australia native species protected by Queensland Government law. Council is attempting to address the growing ibis populations on the small islands and vegetation at the lake, which have also contributed to the excess nutrients in the lake.

As part of Council’s Ibis Management Plan, wildlife consultants try to manage the ibis population through egg and nest management.

Council also recently received approval to proceed with the additional vegetation management plan for the lake. As part of this plan, Council will be undertaking works over the coming weeks to replace some reeds and rushes around the lake with plants that are less suited to ibis roosting to deter ibis from the lake.

Current investigation works

Over the next few weeks, Council will be out on the lake with boats and sampling equipment undertaking important investigations to inform aquatic surveys. This work will help us understand the current conditions and species at the lake, which will inform our investigations to determine the best approach to improve the health of the lake.

If you see the sampling team out on the lake, feel free to drop down and have a look at the work that Council will be undertaking, including lake water quality and sediment analysis, as well as surveying fish and other aquatic species that live in the lake. Our Council team would also welcome any questions from residents who are interested in learning more about the sampling program.

The sampling report will be available in April for those interested in learning more about what lives in the lake and how best to support the fish and other aquatic species that live there.

Student research project 

A Griffith University student research project is currently underway in partnership with Council to model water quality and ecosystem dynamics at Forest Lake. This project is coordinated through the Australian Rivers Institute at Griffith University, as part ongoing research projects undertaken with Council.

The modelling will provide: 

  • an understanding of the present state of the lake’s ecology and water quality
  • the potential future state of the lake through analysis of newly proposed methods and technologies for algae bloom management and sediment deposition. 

The research project is expected to be concluded in late May 2019 and the findings provided to the project team developing the Forest Lake management plan to ensure the long-term health of the lake. 

What you can do

As a local residents living in the lake catchment, you can also play a part in reducing the build-up of nutrients and sediments entering the lake. Some of the things that we can all do in our day-to-day lives to help improve the health of the lake are:

  • washing cars on the lawn
  • reducing fertiliser use, particularly before rain
  • collecting lawn clippings
  • not feeding the ducks and wader birds
  • picking up dog droppings.

Get involved

We're accepting expressions of interest to form a new Habitat Brisbane group in Forest Lake.

If you’re passionate about the environment and are keen to make a difference with hands-on volunteering, phone Council on 07 3403 8888.

Register for updates

Register for updates on the Forest Lake management plan.

More information

For more information:

09 April 2019