Constructed wetlands

Two constructed wetlands on farmland in the Cassowary Coast region are under the spotlight, with new funding announced to monitor how they can improve water flowing to the Great Barrier Reef.

The Great Barrier Reef Foundation is funding a project led by Terrain NRM at the wetland sites in Mourilyan and Tully, which were created almost four years ago as potential water treatment systems to reduce nitrogen runoff from sugarcane farms.

Terrain NRM water quality monitoring leader Alicia Buckle said monitoring over several years as part of the now completed Wet Tropics Major Integrated Project had shown the wetlands’ potential for removing dissolved inorganic nitrogen.

Removing nitrogen from the water

“We have evidence that the wetlands are removing nitrogen from the water cycle but we still have a lot to learn about how dissolved inorganic nitrogen travels through wetlands like these, and under what conditions these sites are most effective at removing nitrogen,’’ she said.

With the new funding, Terrain NRM will be working with James Cook University, Griffith University and scientists from the Queensland Government’s departments of Environment and Science and Agriculture and Fisheries to regularly monitor the wetlands, including during large rainfall events.

Terrain NRM water quality project manager Karen Lindee said results would help to determine the wider scale potential of constructed wetlands on low-lying farmland.

The one-year project is now part of the three-year Tully Johnstone Water Quality Program, funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation. This program is reducing the amount of dissolved inorganic nitrogen entering the Great Barrier Reef’s waters through a range of projects including working with farmers to improve yield and nutrient management, and building a better understanding of water quality issues using local-scale water quality monitoring.

Tully and Johnstone: Priority catchments for runoff reduction

The Tully and Johnstone River basins, on the Cassowary Coast, are priority catchments for nutrient runoff reduction. This is an area with significant sugarcane and banana land, where farmers have been working for a number of years on changing to farming practices which improve water quality.

The Wet Tropics Major Integrated Project, which included both the construction and the previous monitoring of the two wetlands, was funded by the Queensland Government’s Queensland Reef Water Quality Program. This project also focused on reducing nutrient, sediment and pesticide run-off into waterways.