Groundwater Sources (Future)
Since the 1970’s groundwater resources of the sedimentary Perth Basin have been developed to supply drinking water to the metropolitan area and communities connected to the IWSS water grid.
The Perth basin hugs the coast and extends North to the Mid West and South to the Southern Ocean. It has the largest fresh groundwater availability in Western Australia and supports diverse ecosystems including wetlands, lakes and caves. There are three major aquifers in the Perth basin: the superficial (or shallow), the Leederville and the Yarragadee.
The superficial aquifer is connected to the surface and can fluctuate in response to annual rainfall. Water in the confined Leederville and Yarragadee aquifers is separated from each other and the superficial aquifer by an impermeable layer called a confining bed. Water in these aquifers may extend to depths of several thousand metres and may include water recharged tens or thousands of years ago, having less reliance on annual rainfall.
Groundwater from these aquifers supports public drinking water supply, agriculture, mining, industry, public open space and garden bores.
Currently about 50% of the IWSS water grid is supplied by groundwater. Groundwater supplies are relatively low cost and use small amounts of energy. Source protection areas maintain these resources for drinking water supply. The aquifers themselves provide storage of water from year to year.
There are a number of groundwater resources that have been investigated to determine if they could be options for our water future.
The following groundwater sources are currently unproven and would require significant further investigation, including investigative drilling, to test the quality, quantity and viability of the schemes. The Department of Water would need to allocate water for the public water supply to develop these sources and they would require source protection.
The Karnup, Dandalup, Gingin, Jurien and North West Coastal groundwater resources are relatively close to Perth and preliminary estimates indicate they would cost $1.00 a kilolitre to develop for local use. If the water requires piping to distant areas within the IWSS water grid, significant integration costs will need to be added and may potentially double these unit costs.
Most of these sources already have some private water abstraction and are near private land holdings, nature reserves or wetlands. Any development of these potential groundwater resources requires further consultation. In particular, advice from the Department of Water is required as to whether there is any water available for public water supply in these areas.
