The Department of Water scientists' discovery that focuses on the Blackwood River is in the spotlight on World Rivers Day.
The relationship between annual rainfall, groundwater sources and how they impact Blackwood River flows has been revealed in a specialist study of the South West groundwater assessment as part of the Liberal National Government's $12.82 million Royalties for Regions “Regional water availability planning and investigation” project.
Water Minister Mia Davies said communities, businesses, tourists and aquatic species relied on the Blackwood, making this sort of research an invaluable tool for managing the resource.
"We always suspected groundwater flowed into the Blackwood in summer, causing its normally dark brown waters to flow clear but we did not have solid science to confirm this," Davies said.
"Department of Water scientists have, for the first time, been able to trace the full journey of raindrops through the landscape to confirm a direct link between annual rainfall and the aquifer-charged summer flows that keep the Blackwood and parts of the Donnelly, Warren and Capel rivers flowing year-round and Margaret River pools full.
They now know the Blackwood River is unique because it is fresher in summer due to groundwater discharge.
"The reduced salinity allows fish such as Balston's pygmy perch – listed as vulnerable – to return to the main river from freshwater tributaries where they take refuge in winter."
Regional Development Minister Terry Redman said the health of the Blackwood was vital to the communities and businesses that it serviced.
"Regional waterways are assets that promote recreational activities and encourage tourism," Redman said.
"It is significant that Royalties for Regions invests in initiatives that help optimise our groundwater resources to support social and economic growth – with strong collaboration by project partners and the community – to build sustainability and liveability in our regions."
