The Vasse estuary is the most nutrient-enriched estuary in south-west Western Australia. Symptoms of eutrophication are particularly evident in the Vasse estuary exit channel where low oxygen conditions have led to large fish kills.
Low oxygen concentrations result from an imbalance between the rate of oxygen consumption and the natural processes of replenishment. Resetting the balance is challenging. While broad-scale actions – such as the reduction of nutrient loading from the catchment – are underway, water resource managers may look to engineered means to supplement oxygen levels. Artificial oxygenation, while not commonly applied to shallow estuaries, has been extremely effective at improving oxygen conditions in the Swan and Canning Rivers, Perth.
In the summer and autumn of 2015-16 (year 1) and 2016-17 (year 2) the Department of Water and Environmental Regulation undertook a trial to assess if artificially oxygenating the Vasse exit channel upstream of the surge barrier was a viable option for improving water quality. The trial was in response to the poor water quality exhibited in the Vasse exit channel over summer and the risk of fish kills due to low oxygen concentrations. It used the proven concepts of oxygenation, but employed more flexible and less permanent technology than that used by the plants on the Swan and Canning Rivers.
The Oxygenating the Vasse estuary exit channel fact sheet provides a summary of the trial.
