Bottle Bend Lagoon is an example of an inland wetland affected by sulfidic sediments. Located on the Murray River in NSW near Gol Gol, Bottle Bend Lagoon had been permanently full for at least three decades. In 2002, however, the wetland underwent a partial drying event as a result of the sustained low flows in the Murray River and the pH subsequently fell from near neutral to below 3 in under four months, leading to a significant fish kill and impact on vegetation.
Bottle Bend began to feature in the national and international press as a symptom of the prolonged drought and what the future might hold for the Basin. Together with the Murray Darling Freshwater Research Centre, the Working Group were successful in gaining funds from the National Water Initiative to better understand the science behind acid sulfate soils in inland floodplain wetlands and importantly, what might be done to prevent the problem in the first place. To help identify wetlands that might be impacted by acid sulfate soils, the Murray Darling Freshwater Research Centre has developed and easy to follow on-line decision support tool for managers and landholders (see Waterlines report and attached documents).
Murray Darling Wetlands Working Group Ltd. (MDWWG) has maintained an interest in Bottle Bend since first identifying it as a potential site for restoration in the early 1980s. Bottle Bend Lagoon requires a management plan that will build on previous and current work within the region and provide a management framework to implement environmental flows into the lagoon. As an important research site, a management plan will also enable active adaptive management and potential learning from water management that could help understand water management in these systems throughout the Murray-Darling Basin.
In partnership with the former Murray CMA and now with Western Local Land Services, Murray Darling Wetlands Working Group Ltd. has begun considering future management options of Bottle Bend Lagoon to provide for discussion with key stakeholders.
The water has now returned to Bottle Bend thanks to high flows in the Murray River and the transformation is remarkable. Aquatic and riparian plants are returning and ducks and pelicans are a common sight. Though still far from pristine, this wetland has shown a resilience that provides some hope for other wetlands affected by acid sulfate soils and proves we still have a long way to go to understanding this issue.
Sulfidic sediments in inland waterways (website)