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Lower Blackwood River

The Hardy Estuary is situated next to Augusta in the south-west of WA.  It drains nearly 23,000 km2 of land and has highest volume of discharge to the ocean of all south-west estuaries (White 2012).  The majority of this is from the high-rainfall areas of the Lower Blackwood and Scott River systems.

The Hardy Estuary is an iconic system, valued for its beauty, recreational opportunities and ecological values (White 2012).  It is one of the only large estuaries on the WA south coast that is permanently open to the marine environment, supporting an equally unique diversity of water dependant biota.  Amongst other things, it is a critical nursery for fish (White 2012) and an important habitat for migratory waterbirds and other endemic flora and fauna (DEC 2006).

The freshwater rivers that support the Hardy Estuary have their own important ecological, cultural, and economic values.  For example, several of the fish species of the Blackwood and Scott River catchments are listed as threatened (DPIRD 2018, & Beatty et al 2009), and the Blackwood River system is one of only two systems in the Southwest Coast Drainage Division to contain all eight freshwater fishes endemic to the region (Beatty et al 2009).  The Scott and Lower Blackwood catchments also both retain significant amounts of remnant natural vegetation (White 2012).

These catchments also support productive agricultural industries including beef, dairy and blue gum plantations (White 2012).  Unfortunately, these land uses have led to nutrient enrichment, dryland salinity, and acid sulphate soils (White 2012 & Strategen 2005), with several associated impacts to the health of the riverine ecosystems and Hardy Estuary (White 2012 & Strategen 2005).  For example, since 2005 the Hardy Inlet has experienced regular potentially toxic cyanobacterial blooms (White 2012).  The low oxygen concentrations that result from decomposition of excess algae also contribute to fish kills and odours (Kitsios 2007).

Healthy riverine ecosystems protect the estuaries by trapping and processing nutrients and other contaminants.  Therefore, maintaining healthy riverine ecosystems is critical for managing the health of the Hardy Estuary and protecting the intrinsic ecological values of its rivers.