A water treatment trial in the Lower Vasse River over the 2017-18 summer has ended with the removal of large blue plastic curtains used to separate sections of the river upstream of the traffic bridge in Busselton.
Department of Water and Environmental Regulation scientist Svenja Tulipani said despite some issues with summer storms, the trial had gone well.
“The trial involved applications of a new phosphorus-binding clay to sections of the Lower Vasse River to test if algal blooms can be reduced,” Dr Tulipani said.
“The clay product was successful in reducing concentrations of phosphorus and was able to clear algal blooms from the treated areas in the river.
“There were some challenges to overcome when two large summer rainfall events in December and January created significant flow in the river causing the curtains to dislodge and leak water between the separated trial areas.”
Regardless of these set-backs, the trial has proven the effectiveness of the clay product in reducing the nutrient phosphorus and the occurrence of algal blooms where clay has been applied, Dr Tulipani said.
“During this trial, we also tested if the clay application has a negative impact on the small organisms that are living in the sediments and near the banks of the Lower Vasse River.
“Preliminary results of these studies are looking good and do not indicate any effects of the clay on these organisms.”
The project team will now analyse data from the trial and undertake further testing of the locally produced clay product.
“Formulations of the product will be tested for effectiveness in differing environments such as more saline conditions and in drainage channels,” Dr Tulipani said.
“We will also do more detailed testing to ensure that widespread clay application does not have any adverse environmental impacts or long term effect on organisms living in the waterbodies.”
Dr Tulipani said the production method of the clay formula will also be reviewed.
“It is hoped that the current cost of production can be reduced to enable its future broad scale use in controlling algal blooms in waterways,” she said.
This project is part of Revitalising Geographe Waterways and the Regional Estuaries Initiative programs supported by the State Government to improve water quality, waterway health and management of Geographe waterways
For more information on the water treatment trials Lower Vasse River, visit the Revitalising Geographe Waterways website https://rgw.dwer.wa.gov.au/applying-science/lower-vasse-river-and-toby-inlet-science/
