Alluvium was engaged by the City of Busselton and a multi-stakeholder working group to develop a Living Streams concept design for the Lower Vasse River. The river is one of the most eutrophied waterways in Western Australia, suffering from persistent toxic blue-green algal blooms and rapid sedimentation that deposits large volumes of organic matter in the river each summer.
The objective of the Living Streams design is to enhance natural ecological processes to reduce the extent, severity, and duration of toxic blue-green algal blooms, while protecting or enhancing the significant environmental values of the river and surrounding area.
We worked with Josh Byrne and Associates, as well as other local subject matter experts, to develop the design in a collaborative process with the working group, community, and Traditional Owners.
Our design used ecological principles, best practice wetland design and extensive data analysis to develop a concept that will address the problem through multiple mechanisms. When implemented, the concept will create a new stable ecosystem where primary productivity is dominated by vascular plants rather than phytoplankton. Additionally, enhanced natural processes can gradually replace resource-intensive management interventions such as flocculation of nutrients with clay products.
The final concept design consists of removing nutrient-rich sediment from the bed of the river, circulating water through a series of enhanced and constructed wetlands that remove algal cells and nutrients, and modification of the riverbanks to enhance nutrient processing.