Yarragadee Aquifer - Perth water plan

Extract from Hansard

3820. Hon Alison Xamon to the Minister for Mental Health representing the Minister for Water

I refer to recent public discussion about drawing water from the Yarragadee Aquifer in the South-West of Western Australia in order to supplement Perth’s drinking water supply, and ask the following -

(1) Is the Government currently investigating using water from the south-west Yarragadee Aquifer to supplement Perth’s drinking water supply?

(2) If yes to (1), what amount of water, in gigalitres, is being considered and from which sub-area(s) of the aquifer?

(3) What is the total unallocated water available, in gigalitres, from the south-west Yarragadee Aquifer, not counting water that is already allocated to existing licences and licence-exempt users or is reserved for future local use?

(4) Please detail the maximum level of decline, in metres, that has occurred to water levels in the Yarragadee Aquifer over the past 10 years?

(5) In relation to the answer to (4), what role have the following had in causing this decline —

(a) reduced rainfall; and

(b) rates of abstraction?

(6) In regards to figures showing available water and allocation limits published in the Department of Water’s South-West Groundwater Areas Allocation Plan, that were current as of January 2009, have any additional water licences been issued for water from Yarragadee Aquifer?

(7) If yes to (6) —

(a) for how much water; and

(b) in which sub-areas?

(8) Since January 2009, have any changes been made to allocation limits, estimated exempt water usage and/or reserved water supplies relating to the Yarragadee Aquifer?

(9) If yes to (8) —

(a) for how much water; and

(b) in which sub-areas of the aquifer?

Hon HELEN MORTON replied:

The Minister for Water provides the following response:

(1) All options for future water supply will be considered.

(2) No planning at this level of detail has been carried out to date.

(3) Under the current management arrangements, 0.0526 Gigalitres (GL) is available.

(4) Water level decline of up to 3.0 metres (0.30 m/year) have been observed in the Yarragadee aquifer in the southern portion of the Perth Basin since 2001

(5) Rainfall decline has been the main cause of the Yarragadee water decline. Pumping (i.e. abstractions) below the Swan Coastal Plain is important in the decline.

(6) Yes

(7) (a)–(b) Additional water licences issued from the Yarragadee aquifer since January 2009:

(8) Yes.

(9) (a)–(b) Changes to Yarragadee aquifer since January 2009: