Abstractions being set as mound levels peak
Released 04 Nov 2008
The Gnangara Mound's water levels have reached the annual peak and Department of Water monitoring bores show a slight improvement in average water levels on the same time last year.
Water levels across the Gnangara mound generally peak in October, after the end of the winter rains.
The average October level for the Superficial aquifer is slightly better than for the last two years, but the levels are still significantly lower than for the previous ten years.
Groundwater levels are usually lowest in April.
"Over recent years the groundwater levels at the crest of the mound have dropped much more than water levels on the edges of the mound closer to the coast and river," the department's director water resource use Rob Hammond said.
"Licensed abstraction volumes for private water users are fixed from year to year, but the volume abstracted for public water supply varies each year, depending on availability from other sources and on demand management.
"At the end of October, when water levels in the dams and the Gnangara mound have reached a maximum, the next year's groundwater abstraction volume for the Integrated Water Supply Scheme is set."
For 2008-2009 the proposed abstraction limit for the Gnangara and Jandakot mounds is 155 GL, of which approximately 147 GL will come from Gnangara – an increase of about 10 GL from 2007-08.
"This figure is still under consideration, and will be finalised by mid-November," Mr Hammond said.
The department is seeking an annual Integrated Water Supply System (IWSS) abstraction target of 120 GL from Gnangara and Jandakot by 2011-12.
The Department of Water spokesperson said this target is projected to be reached when the second desalination plant comes on line in 2011-12. In the mean time the current efficiency measures are essential to limit the pressure on Gnangara.
Contact: Peter Collins
Phone: (08) 6364 6848 / 0434 603 441