UPDATE #9_Aquatic weed clearing Hoods Lagoon Clermont

Published on 28 November 2022

Isaac Regional Council advises the community that mechanical removal is set to begin tomorrow, Tuesday, 29 November 2022.

The mechanical removal is part of a multi-faceted approach which also includes application of registered herbicides and the introduction of locally bred weevils.

Sourcing the aquatic harvester has been a challenge as other local governments and State Government agencies are also battling with the Salvinia weed infestation.

Council shares the same community frustration as ongoing monitoring and follow-up treatments will be required over multiple years to remove this invasive species from Hoods Lagoon in Clermont.

Mechanical removal

The contractor will work over 10 days to mechanically remove the salvinia weed using a specialist aquatic weed harvester. Following removal from the lagoon, the salvinia will be transported to a disposal area adjacent to Charles Street where it will remain until it breaks down and is no longer a biosecurity risk.

Other areas of Hoods Lagoon will remain open during this process however the public are asked to follow signage and not enter the cordoned off disposal area where the weed will be stockpiled. Salvinia is a restricted plant under the Biosecurity Act 2014 and removal of the plant is an offence.

Council will use two aquatic skimmers to assist in the removal of smaller remaining sections of weed after the use of the aquatic harvester.

Weevil breeding

The release of Salvinia weevils have been released at Hoods Lagoon to assist with the removal of the aquatic weed infestation. While an effective control, the weevils are not expected to produce instant results.

The weevils should spread in large numbers over the coming months and eat through the leaves on the plant causing it to die off. Weevils can take up to two years to reduce an infestation, sometimes less in tropical and subtropical climates.

If residents notice PVC pipes at Hoods Lagoon, please do not retrieve them as they house the weevils and are important to ongoing management of Salvinia weed.

The locations for the weevil release were chosen for the accessibility to sunlight and primary plant growth. As part of Council’s biocontrol breeding program, officers have ensured they are acclimatised.

Lagoon health

Once the weed mat has been removed, Council officers will continue to monitor the lagoon’s recovery and implement ongoing controls.

Mesh fencing

Mesh fencing will remain installed near the causeway as a temporary control measure to contain salvinia in case of a sudden down pour.

Herbicide control

Spraying of Salvinia in the gully downstream from the lagoon has been effective and monitoring continues.

HOW YOU CAN HELP

Council encourages residents to not dispose home aquarium and pond plants into our waterways.

Property owners are reminded 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.

JEFF STEWART-HARRIS PSM
Chief Executive Officer