❓ A WA parliamentary question scrutinises water usage, distribution losses, and desalination plant costs, questioning the effectiveness of water conservation measures and the state's water management strategies. The response acknowledges data inconsistencies and outlines factors contributing to water loss and usage patterns.
AnsweredQoN 2431Legislative Assembly
QuestionView source ↗
(a) is the following information, provided by the Australian Bureau of Statistics and dated 2004-2005, accurate -
(i) 1, 495 gigalitres of water was consumed in Western Australia, up 10% from the 2000-2001 figure;
(ii) water loss during distribution in Western Australia in 2004-2005 was 123 gigalitres, 17% of all water use;
(iii) total household water use was 383 gigalitres, 1 gigalitre less than in 2000-2001;
(iv) per capita use of water in Western Australia was 180 kilolitres, 77 kilolitres more than any other state or territory; and
(v) as of 30 June 2005, the total volume of water stored in the major Western Australian dams was 10,135 gigalitres, 83% of total capacity;
(b) can the Minister explain how 17% of the State’s 2004-2005 water consumption disappeared during distribution;
(c) what would be the cost of 123 gigalitres of water at today’s price;
(d) what is the volume of water that disappeared during distribution in 2005-2006 and 2006-2007;
(e) what would be the cost of this water loss at today’s price;
(f) who is ultimately responsible for all losses of water during distribution;
(g) what must be done to prevent such massive losses;
(h) what was the State’s household water use for 2005-2006 and 2006-2007;
(i) given the Australian Bureau of Statistics data that in 2004-2005, the State’s per capita water use was 180 kilolitres, or an average 43% higher use than any other Australian state or territory, what is the explanation for this;
(j) what was the per capita water consumption in 2005-2006 and 2006-2007 -
(i) in kilolitres; and
(ii) in comparison with the rest of Australia;
(k) can the Minister provide clear and concise information regarding all positive outcomes delivered by the mandatory ban on sprinkler use between 2001 to 2007;
(l) can the Minister provide the actual amount of expenditure for all advertising promoting public restraint in the use of water between 2001 and 2007 inclusive;
(m) can the Minister provide Key Performance Indicator outcome comparisons proving the success of sprinkler bans and related advertising campaigns between 2001 and 2007 inclusive;
(n) can the Minister explain why this State’s distributed water has the highest groundwater content of any Australian state or territory;
(o) as of 31 May 2007 -
(i) what is the volume of water held in the major dams in this State in gigalitres; and
(ii) what volume of water is held, as a percentage of total capacity;
(p) is it likely that the desalination plant, which cost the whole community $387 million and currently delivers only 17% of the metropolitan area water requirements, will hold no realistic provision for the rest of the State;
(q) will the first phase of the proposed desalination plant, with a projected costing of $1 billion, provide just 3.3% of the State’s water requirements, based on the 2004-2005 consumption figure only;
(r) will the second phase, developed at an undisclosed sum, provide just 6.6% of the State’s water requirements, based on the 2004-2005 consumption figure only;
(s) is it true that the current $387 million desalination plant, the proposed $1 billion plant and its second billion dollar phase will not generate enough water to cover the 123 gigalitres that disappeared during distribution in 2004-2005;
(t) will the current and proposed desalination plants, which cost the State a minimum of $2.4 billion in construction costs alone, provide just 7% of total water consumption based on 2004-2005 figures;
(u) is it possible that the provision of the whole of the metropolitan area’s water needs through a desalinated water supply could cost $32 billion in today’s prices;
(v) prior to the 2004 State Election, did the Water Corporation state that the transportation of water from the North-West, which would supply all of the metropolitan area and places in-between, would have an initial facilitation cost of $4.6 billion;
(w) why are the Western Australian horticulture and agriculture industries being singled out as scapegoats for the overuse of water while -
(i) fruit, nut, plantation, berry fruit and vegetable growers use 4.3 megalitres of water per cultivated hectare;
(ii) lawns, such as those surrounding Parliament House, require up to 6.8 megalitres of water per hectare; and
(iii) irrigated agriculture, including horticulture, had a gross value of $545 million in 2004-2005;
(x) why do at least two major Perth hotels have 309 dual occupancy guest rooms without dual flush toilet cisterns;
(y) why do many other major accommodation facilities and large commercial premises not have dual flush toilet cisterns;
(z) why did overall water consumption between 2000-2001 and 2004-2005 fall by 14% in Australia, but rose in Western Australia by 10%;
(aa) despite having relatively similar climates, why do 48% of South Australian households have a rainwater tank compared to 12% in Western Australia; and
(bb) does the Minister’s responsibility for three other major portfolios impede the Minister’s ability to manage the State’s water crisis effectively?
(i) 1, 495 gigalitres of water was consumed in Western Australia, up 10% from the 2000-2001 figure;
(ii) water loss during distribution in Western Australia in 2004-2005 was 123 gigalitres, 17% of all water use;
(iii) total household water use was 383 gigalitres, 1 gigalitre less than in 2000-2001;
(iv) per capita use of water in Western Australia was 180 kilolitres, 77 kilolitres more than any other state or territory; and
(v) as of 30 June 2005, the total volume of water stored in the major Western Australian dams was 10,135 gigalitres, 83% of total capacity;
(b) can the Minister explain how 17% of the State’s 2004-2005 water consumption disappeared during distribution;
(c) what would be the cost of 123 gigalitres of water at today’s price;
(d) what is the volume of water that disappeared during distribution in 2005-2006 and 2006-2007;
(e) what would be the cost of this water loss at today’s price;
(f) who is ultimately responsible for all losses of water during distribution;
(g) what must be done to prevent such massive losses;
(h) what was the State’s household water use for 2005-2006 and 2006-2007;
(i) given the Australian Bureau of Statistics data that in 2004-2005, the State’s per capita water use was 180 kilolitres, or an average 43% higher use than any other Australian state or territory, what is the explanation for this;
(j) what was the per capita water consumption in 2005-2006 and 2006-2007 -
(i) in kilolitres; and
(ii) in comparison with the rest of Australia;
(k) can the Minister provide clear and concise information regarding all positive outcomes delivered by the mandatory ban on sprinkler use between 2001 to 2007;
(l) can the Minister provide the actual amount of expenditure for all advertising promoting public restraint in the use of water between 2001 and 2007 inclusive;
(m) can the Minister provide Key Performance Indicator outcome comparisons proving the success of sprinkler bans and related advertising campaigns between 2001 and 2007 inclusive;
(n) can the Minister explain why this State’s distributed water has the highest groundwater content of any Australian state or territory;
(o) as of 31 May 2007 -
(i) what is the volume of water held in the major dams in this State in gigalitres; and
(ii) what volume of water is held, as a percentage of total capacity;
(p) is it likely that the desalination plant, which cost the whole community $387 million and currently delivers only 17% of the metropolitan area water requirements, will hold no realistic provision for the rest of the State;
(q) will the first phase of the proposed desalination plant, with a projected costing of $1 billion, provide just 3.3% of the State’s water requirements, based on the 2004-2005 consumption figure only;
(r) will the second phase, developed at an undisclosed sum, provide just 6.6% of the State’s water requirements, based on the 2004-2005 consumption figure only;
(s) is it true that the current $387 million desalination plant, the proposed $1 billion plant and its second billion dollar phase will not generate enough water to cover the 123 gigalitres that disappeared during distribution in 2004-2005;
(t) will the current and proposed desalination plants, which cost the State a minimum of $2.4 billion in construction costs alone, provide just 7% of total water consumption based on 2004-2005 figures;
(u) is it possible that the provision of the whole of the metropolitan area’s water needs through a desalinated water supply could cost $32 billion in today’s prices;
(v) prior to the 2004 State Election, did the Water Corporation state that the transportation of water from the North-West, which would supply all of the metropolitan area and places in-between, would have an initial facilitation cost of $4.6 billion;
(w) why are the Western Australian horticulture and agriculture industries being singled out as scapegoats for the overuse of water while -
(i) fruit, nut, plantation, berry fruit and vegetable growers use 4.3 megalitres of water per cultivated hectare;
(ii) lawns, such as those surrounding Parliament House, require up to 6.8 megalitres of water per hectare; and
(iii) irrigated agriculture, including horticulture, had a gross value of $545 million in 2004-2005;
(x) why do at least two major Perth hotels have 309 dual occupancy guest rooms without dual flush toilet cisterns;
(y) why do many other major accommodation facilities and large commercial premises not have dual flush toilet cisterns;
(z) why did overall water consumption between 2000-2001 and 2004-2005 fall by 14% in Australia, but rose in Western Australia by 10%;
(aa) despite having relatively similar climates, why do 48% of South Australian households have a rainwater tank compared to 12% in Western Australia; and
(bb) does the Minister’s responsibility for three other major portfolios impede the Minister’s ability to manage the State’s water crisis effectively?
AnswerView source ↗
Answered
14 August 2007
Responded by
Minister for Water Resources
Response time
62 days
Answer
(a)(i) The Australian Bureau of Statistics's (ABS) Water Account data on the State's water usage is inconsistent with data compiled by the Department of Water (DoW). Generally, the ABS data on water usage is lower than that estimated by the DoW, and published in reports such as the draft State Water Plan.
However, it is likely that both the DoW and ABS data overestimate the amount of household water usage. Both figures are based on estimates of domestic bore use that were derived in the late 1990s and do not take into account the introduction of restrictions on sprinkler use, and the publicity campaigns of recent years promoting water efficient gardening.
The DoW is undertaking measures to improve the consistency of reporting between DoW and ABS estimates of water use. The DoW is also undertaking a selective monitoring program to obtain a more accurate estimate of water use from domestic bores.
(a)(ii) The DoW does not compile information on water losses in distribution in the same format as the ABS (a, ii), so is unable to comment on the veracity of the ABS figures. However, the percentage of water losses reported in the ABS document are broadly consistent with the DoW understanding of losses during distribution.
(a)(iii) The total household use in schemes supplied by the Water Corporation (the Corporation) in 2004-05 was 216 GL. This is 11 GL less than the 227 GL consumed in 2000-01. This net decrease is a combination of:
· scheme savings from the introduction of 2 day per week water restrictions.
· supply increases due to population growth.
· seasonal fluctuations in demand due to annual climatic variations.
(a)(iv) Per capita use is higher than other states as the state comparison includes commercial and agricultural usage and Western Australia has a high per capita output of commercial and agricultural activities.
(v) The volume of water stored in the State's dams is heavily influenced by the Argyle Dam, which at June 2005 contained nearly 95% of the total volume of water stored in major dams.
The Northern dams have a higher volume than Metropolitan and South-West due to differing rainfall patterns and capacity, which misrepresents the water availability situation in Western Australia. This is exemplified by the 91% full dam levels for Western Australia reported on the Water Resource Observation Network, where Metropolitan are currently at 20% capacity, South West 36%, Great Southern 58%, Mid West 72% and the North West dams at 100%.
(b) The DoW does not compile discrete information on water losses in distribution in the same format as the ABS. The percentage however, is broadly consistent with the DoW understanding of losses during distribution, and mainly occurs as a result of water lost through supply infrastructure resulting from:
- leakages in underground pipes; or
- seepage and evaporation from open channels and rivers;
Distribution losses from burst mains, theft and customer meter errors also occur, but to a lesser extent. Based on the ABS report, this figure of 17% is below the national average of 18% of water loss during distribution.
(c) The cost of 123 GL cannot be calculated specifically due to the varying quality and location of this water across the State (i.e. irrigation water compared with scheme water and supplied in areas of varying water scarcity).
(d) With regard to the Corporation's scheme supply, in 2005-06 non-revenue water reported was 23 GL for Perth. The 2006-07 calculation will not be undertaken until after the end of the financial year.
(e) These losses occur at different stages and qualities in distribution and cannot be defined further, therefore the cost of the water cannot be calculated.
(f) The individual holders of the water licence (water utilities, irrigators and irrigation co-ops, private self supply).
(g) The Water Corporation is required to calculate and report losses to the Water Services Association of Australia (WSAA) and National Water Commission as part of the National Performance Reporting Framework. The Water Corporation has reported an Infrastructure Leakage Index of 1.6 and 1.7 for 2004-05 and 2005-06 respectively. This is calculated by current annual real loss/unavoidable annual real loss. According to the WSAA this is in the good to fair range of the internationally utilised Infrastructure Leakage Index (ILI).
Despite this good rating, the Corporation is constantly seeking opportunities to further reduce distribution losses. As an example, network optimisation is being trialled in two Perth Metropolitan areas to reduce pressure in the distribution system with the dual aim of reducing consumption and leakage.
The Water Corporation and Harvey Water are conducting water trading whereby open irrigation channels are being changed to a pressurised pipe system to reduce losses from seepage and evaporation and also to allow more efficient and value-added end uses of this irrigation water.
(h) Water used by households serviced by the Water Corporation's schemes in 2005-06 was 211 GL, comprising 155 GL in the metropolitan area and 56 GL for regional schemes.
Consumption data for 2006-07 has not yet been determined.
(i) The per capita use calculated by the ABS includes commercial, industrial, mining and agricultural use. The per capita use in Western Australia is higher than other states largely because of the high proportion of non-residential use. Climatic conditions, difference in population and housing density also marginally impact per capita water consumption.
(j)(i)(ii) State per capita use of water for households (ie excluding commercial and mining use) supplied by the Corporation's schemes was 114 kL in 2005-06. Consumption data for 2006-07 has not yet been determined.
The State Water Plan 2007 aims to further reduce average household consumption to less than 100 kl per person per year by 2011. This Plan also includes a review of household water use in other areas of the state and identifies opportunities to improve water use efficiency.
(k) The mandatory sprinkler bans has delivered average annual savings of 44.2 GL in the Integrated Water Supply System (IWSS), which is equivalent to a new major water source such as a desalination plant.
The combination of demand management and source development initiatives undertaken by the Corporation has prevented the need for more severe restrictions currently being experienced in the eastern states.
(l) The Corporation has spent $12.6 million on advertising promoting public restraint in the use of water between 2001 and 2007.
(m) Since the introduction in 2001 the public of Western Australia have supported restrictions with an average of 44 million kilolitres saved each year - equivalent to a new major water source such as a desalination plant.
(n) Western Australia's distributed water has the highest groundwater content because it has the highest portion of its water resources as groundwater.
(o)(i)(ii) As mentioned above (question (a), (v)), the percentage of water held in the State's major dams is distorted by the Argyle Dam. The dam has nearly 90% of the State's total large dam storage capacity and is just over 97% full whereas the dams providing water to the metropolitan area are only 24.5% full.
The following table provides the most up to date information on the State's major dams (over 10,000ML capacity) used for either potable or irrigation purposes.
Current Storage (ML)
Total Capacity (ML)
Percentage of Total Capacity (%)
Argyle Dam (Ord River
10,464,340
10,763,000
97.23
Canning Dam
13,869
90,353
15.35
Harding Dam
37,417
63,800
58.65
Harris Dam
33,786
72,000
46.93
Harvey Dam
5,382
56,441
9.54
Logue Brook Dam
6,818
24,321
28.03
Mundaring Dam
25,388
63,597
39.92
North Dandalup Dam
17,632
74,849
23.56
Serpentine Main Dam
31,811
137,667
23.11
South Dandalup Dam
26,238
138,000
19.01
Stirling Dam
12,064
53,769
22.44
Waroona Dam
4,342
14,930
29.08
Wellington Dam
106,484
184,916
57.59
Wungong Dam
16,057
59,796
26.85
(p) The Kwinana Desalination plant is just one of a number of state-wide projects undertaken to increase scheme water. The nature of water sources often requires them to be developed locally.
The desalination plant provides water into the IWSS. The IWSS supplies water to metropolitan Perth, and to parts of the Goldfields, Agricultural and South-West regions.
(q) It is not appropriate to compare the quantity of the proposed desalination plant to the total state-wide water requirements as desalination is a high quality potable water source.
The proposed desalination plant is more appropriately compared to other drinking water quality sources rather than (for instance) water used for mining or agriculture. In that regard, it is anticipated that the proposed Southern Seawater Desalination plant will be the same size as the recently commissioned Kwinana Desalination plant - a source that has increased the capacity of the IWSS by 17%.
(r) As noted above, comparison to total state-wide sources (of which a significant proportion is non-potable water) is inappropriate.
In addition, it is too early to speculate on a "second phase" of the proposed desalination plant. No decision has been made as to when a second phase will be undertaken, nor whether it will in fact be the next major source project when the Southern Seawater Desalination plant is completed.
(s) It is inappropriate to compare a high quality drinking water source used in the IWSS to losses which (for instance) may have been generated through seepage in irrigation channels.
As noted in question (d) losses in Perth in 2005/06 were 23 GL. Such losses are inherent in all utility distribution networks, with the Corporation ranking at the top of the Water Services Association of Australia (WSAA) good to fair range according to the internationally utilised Infrastructure Leakage Index (ILI).
(t) The Kwinana Desalination plant cost $387 million. The proposed Southern Seawater Desalination plant is estimated to cost $955 million. No decision has yet been made on the size nor timing of any further expansions to the proposed Southern Seawater Desalination plant.
Again, a comparison of high quality potable water to total state-wide usage (of which a significant proportion is non-potable water) is inappropriate.
(u) The IWSS is sourced from a combination of groundwater, surface water and desalination sources in conjunction with demand management initiatives. This security through diversity approach will ensure that whilst desalination is an important part of the IWSS supply, it will never be the only supply option.
(v) In 2006, an Independent Review on the Options for Bringing Water to Perth from the Kimberley was undertaken and the review outlined four options in bringing water from the Kimberley region. Based on 200 GL/year scenario, these options are:
Option
Capital Cost (billion)
Unit cost of water ($/kL)
Pipeline
$11.9
$9.7
Canal
$14.5
$20.5
Ocean Tanker
$6.2
$6.7
0.5 GL Water Bag
$5.3
Not calculated
Given the high capital costs and unit costs for each option, the Government has been considering cheaper alternatives in resolving the water crisis in WA.
(w)(i)(ii)(iii) Western Australian horticulture and agriculture industries are not being singled out as scapegoats for the overuse of water. However, in recognition that irrigated agriculture uses about 40% of all water use in WA, the 2003 State Water Strategy and the current State Water Plan address irrigated agriculture water use as one of the most important water use sectors in the State. A review of the irrigation industry resulted in the Blueprint for Water Reform initiating proposed changes to the water allocation and licensing processes in line with the National Water Initiative.
(x) Currently, there is no regulation on dual flush toilet cisterns and it is not compulsory to retrofit these at major accommodation facilities or large commercial premises. Furthermore, as non-residential customers pay approximately the marginal cost of supply, the decision to retrofit dual flush toilets is a commercial one, to be made in light of the cost of undertaking the retrofit.
(y) Refer to answer above (x).
(z) Western Australia has been experiencing a significant economic boom in the last few years with GDP measured at 2.7% in 2004-05 increasing to 4.9% in 2005-06 compared with the national average of 2.7% and 2.8% respectively. Increases in water consumption in the State during 2004-05 can be largely explained in terms of increased industrial activities around the state. Minerals, energy and commerce sectors account for 42% of the total water use by sector with an estimated usage of around 950 GL as explained in the State Water Plan 2007.
(aa) The reason for the different uptake of rainwater tanks is unknown. A rebate for the purchase of a rainwater tank is available under the Waterwise Rebate Scheme. In the four years the rebate has been available 9716 rebates have been granted at a total of $1, 035, 021 million.
(bb) No. The State's water needs are being managed effectively which is evidenced by Western Australia being in a significantly better position than most of the eastern states which are experiencing much more stringent water restrictions.
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(a)(i) The Australian Bureau of Statistics's (ABS) Water Account data on the State's water usage is inconsistent with data compiled by the Department of Water (DoW). Generally, the ABS data on water usage is lower than that estimated by the DoW, and published in reports such as the draft State Water Plan.
However, it is likely that both the DoW and ABS data overestimate the amount of household water usage. Both figures are based on estimates of domestic bore use that were derived in the late 1990s and do not take into account the introduction of restrictions on sprinkler use, and the publicity campaigns of recent years promoting water efficient gardening.
The DoW is undertaking measures to improve the consistency of reporting between DoW and ABS estimates of water use. The DoW is also undertaking a selective monitoring program to obtain a more accurate estimate of water use from domestic bores.
(a)(ii) The DoW does not compile information on water losses in distribution in the same format as the ABS (a, ii), so is unable to comment on the veracity of the ABS figures. However, the percentage of water losses reported in the ABS document are broadly consistent with the DoW understanding of losses during distribution.
(a)(iii) The total household use in schemes supplied by the Water Corporation (the Corporation) in 2004-05 was 216 GL. This is 11 GL less than the 227 GL consumed in 2000-01. This net decrease is a combination of:
· scheme savings from the introduction of 2 day per week water restrictions.
· supply increases due to population growth.
· seasonal fluctuations in demand due to annual climatic variations.
(a)(iv) Per capita use is higher than other states as the state comparison includes commercial and agricultural usage and Western Australia has a high per capita output of commercial and agricultural activities.
(v) The volume of water stored in the State's dams is heavily influenced by the Argyle Dam, which at June 2005 contained nearly 95% of the total volume of water stored in major dams.
The Northern dams have a higher volume than Metropolitan and South-West due to differing rainfall patterns and capacity, which misrepresents the water availability situation in Western Australia. This is exemplified by the 91% full dam levels for Western Australia reported on the Water Resource Observation Network, where Metropolitan are currently at 20% capacity, South West 36%, Great Southern 58%, Mid West 72% and the North West dams at 100%.
(b) The DoW does not compile discrete information on water losses in distribution in the same format as the ABS. The percentage however, is broadly consistent with the DoW understanding of losses during distribution, and mainly occurs as a result of water lost through supply infrastructure resulting from:
- leakages in underground pipes; or
- seepage and evaporation from open channels and rivers;
Distribution losses from burst mains, theft and customer meter errors also occur, but to a lesser extent. Based on the ABS report, this figure of 17% is below the national average of 18% of water loss during distribution.
(c) The cost of 123 GL cannot be calculated specifically due to the varying quality and location of this water across the State (i.e. irrigation water compared with scheme water and supplied in areas of varying water scarcity).
(d) With regard to the Corporation's scheme supply, in 2005-06 non-revenue water reported was 23 GL for Perth. The 2006-07 calculation will not be undertaken until after the end of the financial year.
(e) These losses occur at different stages and qualities in distribution and cannot be defined further, therefore the cost of the water cannot be calculated.
(f) The individual holders of the water licence (water utilities, irrigators and irrigation co-ops, private self supply).
(g) The Water Corporation is required to calculate and report losses to the Water Services Association of Australia (WSAA) and National Water Commission as part of the National Performance Reporting Framework. The Water Corporation has reported an Infrastructure Leakage Index of 1.6 and 1.7 for 2004-05 and 2005-06 respectively. This is calculated by current annual real loss/unavoidable annual real loss. According to the WSAA this is in the good to fair range of the internationally utilised Infrastructure Leakage Index (ILI).
Despite this good rating, the Corporation is constantly seeking opportunities to further reduce distribution losses. As an example, network optimisation is being trialled in two Perth Metropolitan areas to reduce pressure in the distribution system with the dual aim of reducing consumption and leakage.
The Water Corporation and Harvey Water are conducting water trading whereby open irrigation channels are being changed to a pressurised pipe system to reduce losses from seepage and evaporation and also to allow more efficient and value-added end uses of this irrigation water.
(h) Water used by households serviced by the Water Corporation's schemes in 2005-06 was 211 GL, comprising 155 GL in the metropolitan area and 56 GL for regional schemes.
Consumption data for 2006-07 has not yet been determined.
(i) The per capita use calculated by the ABS includes commercial, industrial, mining and agricultural use. The per capita use in Western Australia is higher than other states largely because of the high proportion of non-residential use. Climatic conditions, difference in population and housing density also marginally impact per capita water consumption.
(j)(i)(ii) State per capita use of water for households (ie excluding commercial and mining use) supplied by the Corporation's schemes was 114 kL in 2005-06. Consumption data for 2006-07 has not yet been determined.
The State Water Plan 2007 aims to further reduce average household consumption to less than 100 kl per person per year by 2011. This Plan also includes a review of household water use in other areas of the state and identifies opportunities to improve water use efficiency.
(k) The mandatory sprinkler bans has delivered average annual savings of 44.2 GL in the Integrated Water Supply System (IWSS), which is equivalent to a new major water source such as a desalination plant.
The combination of demand management and source development initiatives undertaken by the Corporation has prevented the need for more severe restrictions currently being experienced in the eastern states.
(l) The Corporation has spent $12.6 million on advertising promoting public restraint in the use of water between 2001 and 2007.
(m) Since the introduction in 2001 the public of Western Australia have supported restrictions with an average of 44 million kilolitres saved each year - equivalent to a new major water source such as a desalination plant.
(n) Western Australia's distributed water has the highest groundwater content because it has the highest portion of its water resources as groundwater.
(o)(i)(ii) As mentioned above (question (a), (v)), the percentage of water held in the State's major dams is distorted by the Argyle Dam. The dam has nearly 90% of the State's total large dam storage capacity and is just over 97% full whereas the dams providing water to the metropolitan area are only 24.5% full.
The following table provides the most up to date information on the State's major dams (over 10,000ML capacity) used for either potable or irrigation purposes.
Current Storage (ML)
Total Capacity (ML)
Percentage of Total Capacity (%)
Argyle Dam (Ord River
10,464,340
10,763,000
97.23
Canning Dam
13,869
90,353
15.35
Harding Dam
37,417
63,800
58.65
Harris Dam
33,786
72,000
46.93
Harvey Dam
5,382
56,441
9.54
Logue Brook Dam
6,818
24,321
28.03
Mundaring Dam
25,388
63,597
39.92
North Dandalup Dam
17,632
74,849
23.56
Serpentine Main Dam
31,811
137,667
23.11
South Dandalup Dam
26,238
138,000
19.01
Stirling Dam
12,064
53,769
22.44
Waroona Dam
4,342
14,930
29.08
Wellington Dam
106,484
184,916
57.59
Wungong Dam
16,057
59,796
26.85
(p) The Kwinana Desalination plant is just one of a number of state-wide projects undertaken to increase scheme water. The nature of water sources often requires them to be developed locally.
The desalination plant provides water into the IWSS. The IWSS supplies water to metropolitan Perth, and to parts of the Goldfields, Agricultural and South-West regions.
(q) It is not appropriate to compare the quantity of the proposed desalination plant to the total state-wide water requirements as desalination is a high quality potable water source.
The proposed desalination plant is more appropriately compared to other drinking water quality sources rather than (for instance) water used for mining or agriculture. In that regard, it is anticipated that the proposed Southern Seawater Desalination plant will be the same size as the recently commissioned Kwinana Desalination plant - a source that has increased the capacity of the IWSS by 17%.
(r) As noted above, comparison to total state-wide sources (of which a significant proportion is non-potable water) is inappropriate.
In addition, it is too early to speculate on a "second phase" of the proposed desalination plant. No decision has been made as to when a second phase will be undertaken, nor whether it will in fact be the next major source project when the Southern Seawater Desalination plant is completed.
(s) It is inappropriate to compare a high quality drinking water source used in the IWSS to losses which (for instance) may have been generated through seepage in irrigation channels.
As noted in question (d) losses in Perth in 2005/06 were 23 GL. Such losses are inherent in all utility distribution networks, with the Corporation ranking at the top of the Water Services Association of Australia (WSAA) good to fair range according to the internationally utilised Infrastructure Leakage Index (ILI).
(t) The Kwinana Desalination plant cost $387 million. The proposed Southern Seawater Desalination plant is estimated to cost $955 million. No decision has yet been made on the size nor timing of any further expansions to the proposed Southern Seawater Desalination plant.
Again, a comparison of high quality potable water to total state-wide usage (of which a significant proportion is non-potable water) is inappropriate.
(u) The IWSS is sourced from a combination of groundwater, surface water and desalination sources in conjunction with demand management initiatives. This security through diversity approach will ensure that whilst desalination is an important part of the IWSS supply, it will never be the only supply option.
(v) In 2006, an Independent Review on the Options for Bringing Water to Perth from the Kimberley was undertaken and the review outlined four options in bringing water from the Kimberley region. Based on 200 GL/year scenario, these options are:
Option
Capital Cost (billion)
Unit cost of water ($/kL)
Pipeline
$11.9
$9.7
Canal
$14.5
$20.5
Ocean Tanker
$6.2
$6.7
0.5 GL Water Bag
$5.3
Not calculated
Given the high capital costs and unit costs for each option, the Government has been considering cheaper alternatives in resolving the water crisis in WA.
(w)(i)(ii)(iii) Western Australian horticulture and agriculture industries are not being singled out as scapegoats for the overuse of water. However, in recognition that irrigated agriculture uses about 40% of all water use in WA, the 2003 State Water Strategy and the current State Water Plan address irrigated agriculture water use as one of the most important water use sectors in the State. A review of the irrigation industry resulted in the Blueprint for Water Reform initiating proposed changes to the water allocation and licensing processes in line with the National Water Initiative.
(x) Currently, there is no regulation on dual flush toilet cisterns and it is not compulsory to retrofit these at major accommodation facilities or large commercial premises. Furthermore, as non-residential customers pay approximately the marginal cost of supply, the decision to retrofit dual flush toilets is a commercial one, to be made in light of the cost of undertaking the retrofit.
(y) Refer to answer above (x).
(z) Western Australia has been experiencing a significant economic boom in the last few years with GDP measured at 2.7% in 2004-05 increasing to 4.9% in 2005-06 compared with the national average of 2.7% and 2.8% respectively. Increases in water consumption in the State during 2004-05 can be largely explained in terms of increased industrial activities around the state. Minerals, energy and commerce sectors account for 42% of the total water use by sector with an estimated usage of around 950 GL as explained in the State Water Plan 2007.
(aa) The reason for the different uptake of rainwater tanks is unknown. A rebate for the purchase of a rainwater tank is available under the Waterwise Rebate Scheme. In the four years the rebate has been available 9716 rebates have been granted at a total of $1, 035, 021 million.
(bb) No. The State's water needs are being managed effectively which is evidenced by Western Australia being in a significantly better position than most of the eastern states which are experiencing much more stringent water restrictions.
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