South of the Ramsar-listed Bowling Green Bay Wetland, on the lands of the Bindal and Wulgurukaba peoples, much of the southern portion of the Lower Burdekin has been converted into an extensive irrigation scheme that underpins the agricultural industry of the region. Covering tens of thousands of hectares, the Lower Burdekin irrigation scheme is predominately used to produce sugar cane.
As careful as farmers are with application rates and methods, inevitably some of the nutrients used to fertilise the cane enter the surrounding waterways in the form of dissolved inorganic nitrogen (DIN) and make their way out to the Great Barrier Reef.
When these excess nutrients reach the reef, they cause algal blooms, reduce coral diversity and contribute to population explosions of the Crown-of-Thorns Starfish, which feed on coral.
The project area is considered part of the Haughton River Basin and designated as a high priority for DIN reductions.
Wetlands have the capacity to filter nutrients from water before it enters the ocean. The biofilms and microbes associated with aquatic plants utilise nitrogen in the water as part of their lifecycle and then release it as nitrogen gas into our atmosphere.
So Greening Australia is working together with local farmers and Sunwater in the Lower Burdekin to harness the nitrogen-filtering capacity of wetland ecosystems and improve the quality of water leaving cane fields in the area.
We’ve identified existing drainage features in the landscape that will be connected to cane drains, augmented and planted with aquatic macrophytes. The existing water infrastructure will be modified to ensure that water spends enough time in the system for the biofilms to be able to use up excess nutrients.
Greening Australia and Sunwater are working together to ensure minimal impact to the groundwater aquifer.
By using constructed wetlands to treat water in this way, the project aims to stop 9.1 tonnes of DIN making its way out to the Great Barrier Reef each year.
This project with Sunwater and Lower Burdekin landholders is part of Greening Australia’s Reef Aid program, and funded by the Great Barrier Reef Foundation’s partnership with the Australian Government’s Reef Trust. For more information, please feel free to send us an online query.
Ben has been restoring landscapes in one form or another throughout much of his career in Southern NSW and Northern Queensland. He is currently working on gully remediation and constructed wetland projects to improve water quality entering the Great Barrier Reef.