Question On Notice No. 2242 asked in the Legislative Council on 2 December 2014 by Hon Lynn Maclaren
Question Directed to the: Minister for Agriculture and Food representing the Minister for Water
Parliament: 39 Session: 1
Question
(1) According to the Department of Water’s report Environmental management of groundwater abstraction from the Gnangara Mound Annual compliance report to the Office of the Environmental Protection Authority July 2012 to June 2011, dated December 2011, the department has installed 60 meters on domestic garden bores located throughout the Perth metropolitan area to determine their average water usage, this is 0.03 per cent of the total number of bores, therefore I ask:
(a) what is the average size of a property with a garden bore, and the average irrigated area;
(b) what is the average size of a property, and its irrigated area, that has one of these 60 metered bores; and
(c) where generally are these 60 metered bores located across the Perth metropolitan area?
(2) How did the department determine that after the introduction in November 2011 of the three-day-a-week sprinkler roster that use per bore would decrease to 440 kilolitres a year?
(3) What assumptions were made for the determination in (2)?
(4) How much would it cost the Government to replace garden bore demand should the superficial aquifer collapse due to climate change and unsustainable abstraction?
(5) How does this cost compare with the current cost of meeting this demand through garden bores?
Answered on 10 March 2015
(1a) The Department of Water (DoW) does not collect this type of data for all properties with a garden bore. The trial covered a representative range of property sizes and irrigated areas in the Perth metropolitan area.
(b) 812 square metres with an average of 310 square metres under irrigation.
(c) The trial metered bores included 30 north of the Swan River and 30 south of the Swan River.
(2) The results of the domestic bore metering trial were used to estimate average water use at 440 kilolitres per year per bore based on a three-day-a-week sprinkler roster.
(3) The DoW assumed that there would be compliance with a three-day-a-week sprinkler roster.
(4) The Government has actions in place to ensure the volume extracted is sustainable.
(5) Not applicable.