Department sets annual draw on Gnangara mound
Released 20 Nov 2008
The Gnangara and Jandakot mounds will supply 147GL to the Perth integrated water supply scheme (IWSS) in the next 12 months after the Department of Water's annual licensing decision for the Water Corporation.
The abstraction figure was set following assessment of dam storage, contingency sources, potential impacts and the demands of the IWSS.
For the 2008/09 year Water Corporation is licensed to abstract 137 from the Gnangara mound and 10GL from the Jandakot mound.
Department of Water director water resource use Rob Hammond said the license figure is set annually after the water levels in the dams and mounds have reached a maximum.
Department of Water's October monitoring of groundwater levels showed the levels to be reasonably consistent over the past two years.
"October 2008 average levels were slightly higher than last year and the licensed abstraction figure is 3.5GL more this year than last year, but 24.8 GLs lower than the year before," Mr Hammond said.
"This small increase is because of lack of late winter rains and operational constraints on alternative sources."
The department has set an abstraction target of 120GL from Gnangara and Jandakot from 2011/12, Mr Hammond said.
This target will be reached when the second desalination plant comes on line in 2011/12, he said.
Mr Hammond said the mound's recharge relies on annual rainfall and the groundwater level is as low as has ever been recorded as a result of the dry climate.
"We are confident that our long term planning will provide stability of the resource under a reduced rainfall climate," Mr Hammond said.
"It is important to note that while comparative monthly annual levels have shown this year to be no worse than the last two years, efficiency measures and the new desalination supply are essential to limit the pressure on Gnangara and ensure its long term sustainability," he said.
Contact: Peter Collins
Phone: (08) 6364 6848 / 0434 603 441