Tonnes of weeds removed from Townsville waterway

More than 180 tonnes of invasive aquatic weeds have been removed from Idalia’s freshwater wetland and northern sediment basin by Townsville City Council during a nine-day intensive program.

Council worked with local company Ausfield Services to remove water lettuce from the waterways to improve the area’s ecological health.

Water lettuce is an invasive plant that grows quickly, blocks waterways and outcompetes native aquatic plants. Because it grows so quickly, too much of the weed can reduce water quality and impact habitat and food availability for aquatic animals.

Before the program started in late April, the weeds covered about 95 per cent of the wetland surface. While aquatic plants can absorb excess nutrients from urban runoff that may enter the water after periods of rain, invasive species can take over and lead to ecological impacts.

Following the nine-day removal program, almost 99 per cent of the weeds were removed using excavators with custom-built sieve buckets, floating booms, pulley systems and crews working on both banks.

Divisional councillor Brady Ellis said these works made an immediate impact on the wetlands.

“I went down to the site every couple of days to see how things were going, and the difference from day to day was huge. The team on site was stoked to see a boost in bird numbers, dragonflies and fish starting from day three,” Cr Ellis said.

“It was really important to the team to manually remove as many weeds as possible from the waterway to reduce the amount of herbicides being introduced to the water. This is an important step in encouraging the long-term health of this natural water system.

“By the end of the program, the team had removed an estimated 510 cubic metres of water lettuce – that’s about the same volume as a family home. This translates to about 180 wet tonnes of this invasive weed that is no longer choking our waterways – a huge win for our environment.”

For the next steps in the program, the team is trialling the release of water lettuce weevils at the wetland to help support long-term water lettuce management. Council teams are exploring continual improvements and management approaches year-round for aquatic weed control on waterways.

The aquatic weeds removed from the site have been taken to one of Council’s Weeds to Healthy Soils piles where, over time, it will transform into resilient soils to be reused to enhance topsoils on our parks and landscapes. Following the weed harvest, about 25 cubic metres of transformed soils were moved back to the Fairfield freshwater weed program site to accelerate the recovery of the grounds where the harvest operation took place.

Mayor Nick Dametto said Council was taking a practical, circular approach to managing excess weeds.

“This is Council getting back to basics, cleaning up our waterways and turning a pest into something useful,” Cr Dametto said.

“Instead of sending weeds to landfill, our team has found a way to turn them into a valuable resource.

“It’s a great outcome because the soil produced from waste will go straight back into Council gardening projects across the city, saving ratepayers money.”

Anyone visiting the waterways may notice a green tint to the water or a mild odour as the water settles and the system rebalances during the coming weeks.

Learn more about invasive plants and animals in Townsville.