Central Coast Council is collaborating with the University of New South Wales (UNSW) in testing a new way to encourage Australian native fish to move across creek and river weirs improving native fish migration.

We welcomed the use of Mangrove Creek and Ourimbah Creek to test the new design currently being pilot tested across Australia.  

The Central Coast’s waterways are valuable water resources and ecosystems that support our drinking water supply, and Council’s weirs are essential mechanisms in the water harvesting process.

Council supports efficient and cost-effective approaches in building a sustainable and resilient water future, including minimising the impact of water harvesting upon the environment. If fishway tests are successful, the new design could support and improve our existing mechanisms in our creek weirs.

Unlike alternative fishways, ‘The Tube Fishway’ works through a self-powered, water propulsion design that could offer greater benefits compared to other fish passage options, as it:
•    is cost effective to manufacture and install
•    is more easily retrofitted to existing structures
•    offers a simplified maintenance as there are minimal moving parts in its design
•    is possible to scale up and be installed on high-level dams, and
•    can be deployed and removed rapidly, meaning they could be installed temporarily during peak migration periods.

PhD Student Hiruni Kammanankada and Supervisor Dr Jasmin Martino, from the Water Research Laboratory and The Centre of Ecosystem Science, UNSW Sydney, are part of a team of academics designing and testing ‘The Tube Fishway’ in accordance with regulatory bodies.

Ms Kammanankada says “Across January to March this year, in Mangrove and Ourimbah Creeks we conducted systematic design experiments to optimise attracting fish to piped systems. This is important fundamental research before the full deployment of the Tube Fishway that we aim to perform later this year.

“We successfully attracted 1,089 fish to our attraction unit across both sites. From this data we aim to crack the secret of what are the best conditions to attract local native fish such as Australian Bass, Flathead, Sea Mullet and Freshwater Herring into piped systems,” Ms Kammanankada said.

UNSW will return to Mangrove Creek and Ourimbah Creek to further test ‘The Tube Fishway’ in September in preparation for the fish breeding migratory window in Spring-Summer 2024-25. Whereas earlier testing focused on attracting the fish to the tube, experiments in September will focus on lifting the fish over the weirs.

The collaboration with UNSW’s Water Research team supports Council’s long-term vision and Council’s Water Quality Program.

We are committed to seeking new opportunities and partnerships that contribute to regional health and prosperity. Collaborating with UNSW is another example of continual improvement of Council’s Water and Sewer department in supporting a sustainable water future.

The project is funded by State Government grants including NSW Government Recreational Fishing Trust.

Further information
A weir is a small barrier built across a creek or river that raises the water level slightly on the upstream side to enable the collection of water. Weirs hold some of the water back to enable pumping but also regularly allow water to flow over the structure as well. A fishway enables fish to cross the weirs even in times of lower flows.

Many native Australian fish are diadromous, so they move from brackish (salty) water downstream to fresh waters upstream during breeding season, whereas introduced species may be more resilient.

Central Coast Council’s three weirs are part of the water harvesting process that help to maintain continuous, safe drinking water for Central Coast residents and businesses. Water can be pumped from Mangrove Creek Weir to the Somersby Water Treatment Plant, Water is also pumped from Ourimbah Creek Weir and Wyong River Weir to Mardi Dam where it is then treated at Mardi Water Treatment Plant.

For more information about Council’s water supply system visit ‘water supply services’ at centralcoast.nsw.gov.au