Rous County Council (Rous) is asking the Northern Rivers’ community to report possible sightings of the highly invasive weed Frogbit ahead of the summer months when typical weather conditions are ideal for it to spread.

Frogbit (Limnobium laevigatum) is a fast-spreading aquatic weed that poses a significant risk to the region’s waterways and aquatic animals.

Frogbit forms large thick mats across the water’s surface, which blocks waterways and irrigation channels and prevents native plant species from growing. Additionally, incursions of Frogbit reduce light, food and shelter for fish and other aquatic animals.

First detected in Queensland, Frogbit has more recently been found in the Northern Rivers due to flood events and by plant and aquarium enthusiasts who have purchased it from interstate dealers unaware of its status as prohibited matter in New South Wales.

Rous’ Weed Biosecurity team is working to ensure it does not establish in the region, according to Rhett Patrick, Weed Biosecurity and Bush Regeneration Manager at Rous.

“This plant matter can quickly become established in its new environment, dominating the ecosystem and reducing biodiversity,” said Rhett Patrick.

“Prior to the 2022 floods, the Northern Rivers had only one known Frogbit infestation in the Tweed Shire. However, the force of the floodwater dispersed the weed into new areas downstream.

“An infestation of Frogbit was also found in the Byron Shire last year and our Weed Biosecurity team spent six months controlling the area to reduce the risk for it to spread.

“We are continuing to monitor both sites and surrounds. However, as a flood-prone region with an abundance of rivers, creeks and waterways to disperse invasive weeds, it is vital that the local community and Rous work together to prevent any further infestations.

“This is especially important as we move into the summer months, when the weather typically becomes wetter and warmer, increasing the potential for the spread of Frogbit.”

Frogbit is classified as Prohibited Matter in NSW under the Biosecurity Act (2015), making its possession, movement or sale illegal.

As the Local Control Authority, Rous has legislative responsibilities to manage weeds in accordance with the Biosecurity Act (2015), accompanying regulations and regional plans. According to these regulations, Rous’ role is to specifically manage priority weeds.

Priority weeds, such as Frogbit, are new and emerging weed threats to the region that have been assessed as posing serious environmental and economic impacts. Decisions regarding which weeds are a priority are made by State and Regional Weed Committees, the Department of Primary Industries and other advisory bodies.

To report any possible sightings of Frogbit, the community is encouraged to contact Rous by calling (02) 6623 3800, or using the ‘report a weed’ webform: rous.nsw.gov.au/report-a-weed.