Assessment of Fire Impacts

An assessment of fire related damage on priority river systems was undertaken in April 2009 to facilitate their recovery. These priority streams were the Big, Rubicon, Taggerty, Steavenson, Acheron, Murrindindi and Yea Rivers and King Parrot, Sunday and Dry Creeks. Some minor tributaries were also assessed.

The principle aim of the initial assessment was to develop a works program (including emergency works) for the CMA to implement onground works. Many site issues identified have since been addressed, however new and emerging issues are requiring further investigation and on going management. River health bushfire related issues the GB CMA continues to work on include:

  • Impacts of post fire runoff, which can have a major affect on aquatic life due to the introduction of large quantities of sediment and ash into waterways changing stream turbidity and ecosystem functioning. Further, increased sediment and ash runoff can kill aquatic organisms by reducing the amount of dissolved oxygen in the water and by clogging the gills of fish with very fine sediment. 
  • Post fire ash and sediment is often transported through the system episodically and deposited at various locations within the channel dependant on rainfall runoff. The severity of impacts of sediment and debris inputs will depend on rainfall intensity, burn severity and the gradient of the landscape. 
  • Potential river avulsions due to an increased level of debris in the stream and consequent flooding and debris flows (ash, sediment and cobbles and large wood) following large events post burn. 
  • Re-emergence of weeds along waterways. Plans are underway to notify landholders adjoining primary waterways within the burnt area of intended pest plant control works to be coordinated and supervised by the GB CMA. These works will be undertaken December 2009 - April 2010, complimenting similar works undertaken by other government agencies on public and freehold land.