Coombabah Creek sediment & tidal study

  • Project typeOcean, beaches & waterways
  • Project scheduleDecember 2020 to late-2023
Coombabah catchment aerial view

We are assessing the condition of Coombabah Lake and surrounding estuary against projected changes in climate, rising sea levels, changing weather patterns and runoff from the upper catchment.

Current status

Coombabah Lake and surrounding estuary is part of the Moreton Bay Marine Park and is a declared Fish Habitat Area. The Coombabah wetland system is classified as a wetland of international significance under the Ramsar Convention. This wetland system is home to a variety of key fish species, migratory birds, ecosystems, and marine and freshwater plants.

Identifying current issues

Rising sea level may change the depth and extent of the lake and estuary, which in turn will affect the extent and composition of the intertidal ecosystems and wetland values.

Project details

The City and the Queensland State Government Department of Environment and Science coordinated the following investigations between 2020 and 2021.

Tidal levels and bathymetry

In late 2020, the Department of Environment and Science deployed several tidal gauges in the lake and estuary and surveyed the topography of the lake. Data was observed for 18 months and has been used to identify historical changes in hydrology dynamics.

Vegetation survey of the surrounding wetland area

In 2021, the Department of Environment and Science conducted a vegetation survey of Coombabah wetland to identify changes in vegetation patterns and its relationship to changes in tidal levels.

Sediment and benthic invertebrate study

In June 2021, the City conducted a study of the sediment source, pollutants and biological health of Coombabah Lake and estuary. The results have been compared to studies from 20 years ago.

Stakeholder workshop

In April 2023, a workshop was held with scientists from the City and Department of Environment and Science to share findings and datasets from our recent ecological, tidal and vegetation investigations. The lake was surveyed again in June 2023 to see if any changes occurred following the extreme rains in February and March 2022.

The next step is to combine the outcomes of the studies and incorporate the results into an easy to understand 'story' explaining the state of the waterway, changes in the lake and wetland, and future state of the wetland system. 

This up to date understanding of Coombabah Lake, estuary and wetland, will be used to help develop a fit-for-purpose Biodiversity and Ecosystems Climate Coastal Adaptation Plan.

Informing the community

The Coombabah Lake story is expected to be finalised by late-2023. We will then share the story, results of the various studies, and future management plans with the community.

Project benefits

Assessing the area will bring many benefits:

  • data to support management decisions for climate adaptation of protected ecosystems in our city
  • understanding of the current ecological health conservation of mangrove, saltmarsh ecosystems and freshwater wetlands protect significant habitat for key fish species
  • support sustainable recreational fishing including bream, estuary cod, flathead, garfish, luderick, mangrove jack, sea mullet, tailor, whiting, banana prawns and king prawns
  • increased recreational opportunities including canoeing, walking, and bird watching
  • an increased relationship between the local community and the water environment.

This project supports advancing climate science action under the Queensland Climate Adaptation Strategy (Q-CAS) and is aligned with the Biodiversity and Ecosystems Climate Adaptation Plan for Queensland.