Submerged debris program
Storms and floods in 2021 and 2022 washed large amounts of debris into waterways. This program is to locate and identify submerged (underwater) flood debris in rivers and to remove it where it poses a hazard.
The program uses sonar technology to detect items submerged below the water level. Sonar technology mounted on boats sends out sound waves and measures returning echoes to detect hazardous items on the riverbed.
Once these items are identified they can be removed by our clean-up contractors where they pose a safety and navigational hazard or will have a detrimental effect on the river habitat if it remains in the river.
The data collected will also help other government departments to assess underwater feature changes in key river channels that may present as a navigation hazard in flood impacted river systems. It will also help with habitat management.
The program is being led by the NSW Environment Protection Authority (EPA) and will contribute to navigational safety in rivers for the community and industry. The submerged debris program is funded under the joint Commonwealth-State Disaster Recovery Funding Arrangements.
What debris is not eligible?
The removal of submerged flood debris that is not a safety or navigational hazard is not eligible.
Waterways located on private land are not eligible under this program.
If you are in a Disaster-Declared area your local council is the first contact point for information on what assistance is available for submerged debris.
How will it work?
The NSW EPA continues to work closely with NSW Maritime and the Department of Primary Industries - Fisheries to identify priority areas on rivers to focus sonar surveys. Intelligence is also provided by the public, the fishing industry, councils and organisations such as OceanWatch is also being collated to inform surveys.
The EPA has appointed Hydrographic & Cadastral Survey and SandMap to do the sonar surveys in the priority areas.
Benefits of the program
- Identifying and removing submerged debris under the waterline, reduces the safety risk to those using the water.
- Debris collected will be separated into waste types to allow for recycling or re-use and diversion from landfills where possible.
- Any hazardous waste will be assessed and removed by qualified experts.
- Clean up focuses on debris that is safe to remove and does not result in additional environmental harm in rivers.
What has been achieved so far?
High resolution sonar surveys have been completed for a number of rivers in Northern NSW. Comprehensive data was collected for priority locations on the Tweed, Wilsons, Richmond and Clarence Rivers. Surveys have been completed for priority locations at Camden Haven Inlet.
Surveys are currently underway on the Nambucca River.
The Hawkesbury River is being resurveyed in certain locations due to additional flooding events this year that caused significant changes to the river. Surveys have been completed between Laughtondale and Spencer, at Windsor Reach and are planned for areas between Cattai and Lower Portland.
Submerged debris removal
Sonar data has been used to remove items which were presenting significant hazards to safety or the environment. Initial reviews are conducted with NSW Maritime and DPI Fisheries before specialist dive teams investigate hazards and take required action. Activities include:
- Tweed River
12 items removed including large trees and manmade items presenting hazards to navigation and bridge infrastructure, and cars which were presenting hazards to the environment.
- Richmond River
Crews are currently removing or trimming hazardous trees; including three trees that were a risk to Woodburn bridge and two large trees that were a navigational risk. Crews have also removed a large diesel tank and a vehicle that was a risk to the environment.
- Hawkesbury River
One submerged vehicle has been removed near Windsor and crews are currently working to remove a large, submerged shipping container. Works are underway to remove other submerged trees which present navigational hazards.
What is happening next?
We continue to work with NSW Maritime to identify further priority riverbed areas to focus hydrographic surveys and assess any potential hazards identified.
Surveys works on the Hawkesbury, Macleay, Manning, Hastings and Nambucca rivers are expected to be complete by the end of December 2022. Submerged hazards will continue to be removed in December 2022 and in early 2023.