Farm wetlands to improve water quality

A water monitoring program at wetlands on farms is helping scientists and landholders to learn more about how wetlands work as treatment systems for nutrient and sediment runoff.

Water samples have been collected from two constructed wetlands in the Innisfail and Tully region of Far North Queensland over the past five years, both on a regular basis and during large rainfall events.

Terrain NRM’s project officer Maria Ribbeck said the data was providing valuable insights into the way wetlands function and their extensive capacity to filter pollutants and improve water quality.

Learning the best wetland conditions for nitrogen removal

“It is also helping us to learn the best conditions for wetlands to optimise removal of nitrogen from the water cycle,’’ she said.

“One of the two constructed wetlands is on eight hectares of low-lying land on a farm managed by Tully Sugar Limited. The data has shown us it’s a high-performing site, with capacity to remove an over 1000 kg of nitrogen a year from the water passing through the wetland.”

Greg Shannon, Cane Productivity and Development Manager at Tully Sugar Limited, said the project was raising awareness of wetlands and their usefulness in the farming landscape.

“The last year’s findings were recently presented to us,’’ he said. “This project has helped us understand how wetlands work and how we can optimise their ability to treat water. The longer this wetland is monitored, the more data we can get, and this will make the findings more and more useful for our decision-making in terms of wetland maintenance and management as time goes by.

“It probably should be noted that not everyone can have a wetland like this on their farm, but we had a piece of cattle grazing land with a natural depression in it already, so it was possible to develop it into a wetland with help from Terrain NRM and the Wet Tropics Major Integrated Project.”

Monitoring at two constructed wetlands

The two constructed wetlands have been monitored for the last year through the Tully Johnstone Wetlands Monitoring Project, funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation.  Terrain NRM has worked with James Cook University, Griffith University and the Queensland Government’s departments of Environment and Science and Agriculture and Fisheries on the project.