Bushfires not only have the power to destroy crops, native bush,
livestock and homes, they can also affect the water quality in
our creeks and rivers. These impacts can range from short-term
changes noticed immediately after the fire to long-term impacts
that can last for many years.
Fire can result in an increase in nutrients and sediment in rivers.
Nutrients can be released from sediment or debris from burnt vegetation,
or can come from ash and smoke that can be carried to the water
by wind or through run-off following rain.
The volume of run-off from a catchment can increase after a fire
and this can lead to increases in the amount of sediment entering
the river. This excess run-off has the capacity to change the
channel structure and flow, through bank erosion and sediment
deposition. In some cases this alteration may be beneficial, such
as, providing additional habitats or refuge pools in the river,
particularly for fish.
The EPA monitored the recovery of the Tod River on the Eyre Peninsula
for one year following the bushfire on the 11th January 2005 in
which more than 80,000 hectares of land north of Port Lincoln
was burnt. The impacts of the fire on the water quality were found
to be minor and very short-lived. As the aquatic macroinvertebrates
in the Tod River are quite tolerant and able to withstand the
brackish and ephemeral nature of this river, they were not affected
by the minor changes in water quality due to the bushfire. It
is possible that more long-term changes to the river may become
apparent in the future. Additional monitoring of the Tod River,
through the EPA's Ambient Monitoring Program, will enable us to
determine if long-term changes are occurring.
Monitoring the recovery of the Tod River following the Eyre Peninsula bushfire of January 2005 (313 KB PDF)
