Update #5 Aquatic weed clearing, Clermont and St Lawrence

Published on 07 September 2022


Isaac Regional Council continues to consult with other Councils and Biosecurity Queensland on ways to manage the recent expansion of Salvinia weed in Clermont and St Lawrence.


Council has sourced and contracted an aquatic harvester to remove the Salvinia weed. The custom-made work boat collects and transfers the weed to a truck for appropriate disposal. The harvester is expected to arrive in Clermont within the next six weeks. Council is working closely with the contractor who has also been engaged to assist other Councils in the removal of Salvinia weed. Once the bulk of the weed is removed, Council will implement follow up control measures on the remaining Salvinia and monitor for further infestations.

St Lawrence

Salvinia weed was flushed over the weir during heavy rainfall events but may re-establish with time.  Further measures are being developed to limit the impact.


This year, Council has used integrated pest management practices to attempt to control the spread of the invasive weed including:
Mechanical removal of large dense shallow mats.

  • Strategic spraying where the Salvinia is dense and mechanical removal is unsafe and or inhibited by native plants.
  • Sourcing and introducing of the Salvinia weevil (Cyrtobagous salviniae). The cold weather has impacted the effectiveness of the biocontrol, but this should improve with warmer weather.
  • Council continues to consult with other Councils and Biosecurity Queensland on ways to manage the recent expansion of Salvinia weed in St Lawrence and Clermont.


It is the first time Hoods Lagoon at Clermont has had an infestation and as a precaution a surveillance survey on Theresa Creek Dam indicated Salvinia was not present.

Initially used in the aquarium trade because of its hardiness and ease of cultivation, Salvinia weed rapidly covers water surfaces and damages water quality, access, and visual appeal. Its growth rates and the challenges it presents being on water and not on land, has proven difficult to control. Control programs on large infestations are very intensive and require a multi-year commitment. Residents might not see a Council officer at the sites however we are working hard to limit the impacts of Salvinia weed.


Council encourages residents and property owners to be vigilant and if you suspect Salvinia on your property, contact Council’s Customer Service Centre on 1300 ISAACS (1300 47 22 27) for identification and information.

Visit https://profiles.ala.org.au/opus/weeds-australia/profile/Salvinia%20molesta for more information.

Chief Executive Officer


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