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.

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 on Forest Lake and improve the health of the lake ecosystem
Latest update

Project commenced February 2019

Council has completed initial ecological investigations on the lake. Find out more.

The project team has also begun work on the strategic management plan to improve the lake’s health long-term. 

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

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
  • algae scum collection and disposal.

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 has begun works to remove some vegetation and will replace some reeds and rushes around the lake with plants that are less suited to ibis roosting to deter ibis from the lake.

Recent findings from investigation works

Since March 2019, Council has been out on the lake with boats and sampling equipment undertaking important investigations to get a more in depth understanding of water quality by sampling throughout the water column at different depths.

The key findings from the ecological investigation works are as follows.

  • Forest Lake supports an array of biodiversity including six native fish species, over 50 bird species, a high diversity of aquatic macroinvertebrates and three native submerged aquatic plants.
  • Despite recent algal and salvinia blooms, the presence of aquatic macroinvertebrates and native submerged aquatic plants indicate better water quality than expected. These species are usually quite sensitive to changes in water quality and poor light penetration.
  • The six native fish species identified include eel-tailed catfish, spangled perch, garfish and eels, and occur in healthy numbers.
  • Although only a few turtles were sampled formally as part of the investigations, a large number of short-necked turtles were observed and believed to be in good health.

This work has helped us understand the current conditions and species at the lake, which we are using to determine the best approach to improve the health of the lake.

If you are interested in learning more about what lives in the lake and would like a copy of the sampling report, please email the project team. You can also register for updates.

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 strategic management plan. 

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 have 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 number of sites including Desoto Park and Hancock Park-Pine Village Park have been suggested by local residents as potential Habitat Brisbane sites. Although not directly located on the lake, Desoto Park has bushland registered as Endangered Regional Ecosystems and is a strategic corridor linking Greenbank and Oxley Creek, with run-off into Forest Lake.

If you are interested in joining the group or learning more, please email the project team.

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:

  • 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).
Last updated:19 June 2019