CANNING
RIVER — ECOSYSTEM HEALTH
137. Hon LYNN MacLAREN to the minister representing the
Minister for Environment:
(1) Given that
the report ''Ecosystem health in the Canning River, focusing on the
influence of the Kent Street Weir: Assessed December 2009 – September
2011'', released by the Department of Water, concludes that values of
the river system are exposed to stresses from the developed catchment, does the
government have a strategy to reduce the pressures from sediment, nutrients and
other contaminants?
(2) If no to (1), why not?
(3) What measures
has the government put in place to respond to the continuing or worsening
stresses on the system expected by reductions in rainfall predicted under even
conservative climate change scenarios?
Hon
HELEN MORTON replied:
(1)–(3)
The ecology of the Kent Street Weir pool is important and I am advised that
more than 30 species of fish, crustaceans and tortoises were identified in the
report to which the member refers. The fish community as a whole has improved
over the past five years. The report indicates that there appears to be little
risk to the ecosystem or human health. However, the environment directly around
the weir is under pressure due to a range of factors including periodic
factors, including periodic salinity, declining stream flow, nutrients and
contaminants. This government is committed to improving the rivers and a great
deal is being done to improve this section of the Canning River under the ''Healthy
Rivers Action Plan''. A number of large-scale artificial wetlands to
trap sediments and contaminants have been constructed along drains and
waterways that flow into this section of the Canning River, such as at Liege
Street and Wharf Street in Cannington and Anvil Way in Welshpool.
The importance of continuing
in-river interventions such as oxygenation and the application of Phoslock in
the Kent Street Weir pool has also been confirmed through this study. The
government is investing $2.4 million in the upgrade of the two existing and
ageing oxygenation plants at Bacon Street, Wilson, and Camsell Way, Ferndale,
and the construction of a new, third plant at Nicholson Road Bridge in
Ferndale.
Low rainfall and stream flow in
recent years is placing additional stress on our rivers, including this section
of the Canning River. This is somewhat offset by augmenting stream flows in the
Canning River with additional scheme water during the drier months in
accordance with the Canning River surface water allocation plan. This latest
report will help inform the management of Kent Street Weir during years of low
flow to ensure that the freshwater environment upstream of the weir is
protected and improved.