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Office of the Commissioner for Sustainability and the Environment



ACT State of the Environment 2007

Indicator: Water use

Summary

While discussion of this indicator will focus on the 2003–07 reporting period, it needs to be viewed in the context of the prolonged drought and the 2003 bushfire both of which have engendered intense community and government discussion. This reflects growing realisation that new approaches to water resource management in the ACT are needed.

During this reporting period, the ACT experienced inflows to water supply reservoirs at 36% of average recorded runoff inflows. This, with increased uses of water, has seen water storage levels fall to 31% of capacity and consequential water restrictions for ACT residents as well as reductions in environmental flows.

The impact of the prolonged drought on water supply remains a critical issue for the ACT. The combination of current and future population growth, environmental flows, the current drought, and future climate change are forcing a cultural shift toward a number of measures to improve water use efficiency. Considerations for diversification of sources of water include increased storage capacity, basin transfer schemes and water recycling.

What the results tell us about the ACT

The key issue for this reporting period has been the decreased availability of water as a consequence of the drought. Storage levels have dropped from 96% in December 2000 through 45% in June 2003 to 36% by the end of June 2007 (Figure 1 and Table 1). During this period the lowest level recorded was 31% in June 2007 (ActewAGL 2007).

The drought has resulted in a decrease in water runoff. Since 2003 there has been an average of approximately 36% of the normal runoff (ActewAGL 2007). The low rainfall has additionally contributed to low groundwater recharge rates that have led to low river base flows in the Territory's catchments.

The water resource

ACT average annual runoff is calculated as approximately 465 GL with 272 GL designated as environmental flows and approximately 193 GL available for human consumption. This is the first state of the environment report for which licensed use for both surface and ground water has been available for all subcatchments in the ACT.

During the reporting period between 52 and 55 GL was used per year with 27 to 29 GL per year returned to the Molonglo River as treated effluent. The remaining volume of what was designated for consumption by the ACT becomes part of the water stored in Burrinjuck Dam for use downstream. The Murrumbidgee basin's drainage system has been modified as a result of construction of dams for hydroelectricity generation, irrigation, municipal water supply and provision of ornamental lakes. Some 27% of the runoff that would have reached the ACT, as measured at the Mount McDonald gauging station on the Murrumbidgee River, is diverted from the catchment at Tantangara Dam for hydroelectricity and irrigation. The numerous farm dams and the clearing of native forest for other land uses have also had an impact on stream flows. In addition, a number of dams have been constructed on the Cotter and Queanbeyan rivers (Table 2) as part of the Canberra and Queanbeyan water supply and within the urban area as part of the storm water system.

Inflows during the reporting period have remained significantly low compared to the measured inflow average, a record measured since 1871. Table 1 outlines the yearly inflow as a percentage of the average with a minimum during the reporting period of 14% in 2006. The effect of the drought on the water supply inflow has been reflected in the storage volume of the Territory's reservoirs.

Table 1: Percent inflow of the recorded average, 2003–07
Year 2003 2004 2005 2006 2007
% inflow 47 31 56 14 35

Note: average = 190 GL; Source: ActewAGL

Table 2: Dam capacities for ACT and Queanbeyan water supply
Bendora Corin Cotter Googong
Catchment area (square kilometres) 91 196 192 890
Full volume (gigalitres) 10.720 75.455 4.697 124.510
Elevation when full (metres) 778.20 955.54 500.69 663.00

Note: 1 gigalitre = 1000 million litres; Source: ActewAGL

Figure 1: Dam storage levels (as percentage of full storage levels), June 2003–July 2007

Graph of the combined fullnes of all Canberra's water supply dams

Note: Full storage = 207 GL; Source: ActewAGL

Water use

Following implementation of community awareness measures and water demand management strategies, water consumption for the reporting period has overall been low. Figure 2 and Table 3 outline water consumption for the reporting period. Table 4 summarises allocation of water during the reporting period.

In an effort to reduce water consumption and extend the availability of water during the continuing drought, a suite of water demand management strategies has moderated water consumption for the ACT during the reporting period. During the reporting period, demand management strategies have saved approximately 93 GL. This is the equivalent of approximately 18 months water supply, a figure based on modelled data generated by ActewAGL.

Figure 2: Average daily water consumption (ML/day), July 2003–April 2007

Graph of average daily water consumption (ML/day), July 2003 to April 2007

Source: ActewAGL

Table 3: Water consumption for Canberra and Queanbeyan, 2003–04 to 2006–07
Period 2003–04 2004–05 2005–06 2006–07
July 3,324.0 3,484.2 3,215.9 3,254.8
August 3,322.4 3,716.3 3,532.0 3,450.8
September 3,484.1 3,257.2 3,379.7 3,916.0
October 3,373.5 3,623.1 3,708.6 5,894.1
November 4,089.4 3,813.7 3,641.3 5,208.4
December 4,338.4 4,464.6 4,367.1 5,774.4
January 5,357.5 5,413.1 5,916.3 5,295.2
February 5,186.0 4,506.2 6,028.2 4,374.5
March 6,354.6 5,579.4 6,951.6 3,714.1
April 5,377.5 5,199.3 5,340.4 3,971.8
May 4,616.7 5,040.9 4,676.5 3,289.2
June 3,434.4 3,621.3 3,582.4 2,917.0
Annual 52,258.05 51,719.3 54,340.0 51,060.3

Source: ActewAGL

Table 4: Uses of water supplied, 2000–01 to 2006–07
Category 2000–01 2001–02 2002–03 2003–04 2004–05 2005–06 2006–07
Residential water supplied (ML) 36,576 40,031 39,646 31,492 30,989 34,436 31,954
Commercial and industrial water supplied (ML) 14,681 15,838 16,129 12,739 12,519 14,177 13,642
Other water supplied (ML) 6,667 4,974 4,955 4,278 4,760 3,857 2,103
Total urban water supplied (ML) 63,045 66,089 65,939 52,560 52,275 56,823 51,779
Average annual residential water consumption (kL/property) 315 325 320 248 240 261 240
Water supplied per total property (kL/property) 467 464 457 357 355 377 341
Volume of bulk water exports (ML) 5,121 5,246 5,209 4,051 4,007 4,353 4,110

Source: ActewAGL, National Performance Report 2005–06

Groundwater use

Introduction of a compliance program for groundwater licence holders resulted in an increase in both the licensed volume data and the extraction data for ACT groundwater during this reporting period (Table 5). These data showed that as well as total licensed volume, actual extraction was within the sustainable yield of groundwater in all of the Territory's 32 water management units. During this reporting period 45 new groundwater bores were licensed thus demonstrating an increase in groundwater license numbers over those for previous reporting periods. The majority of these were located within the inner urban Lake Burley Griffin sub catchment.

While the increase in groundwater use appears to be significant, the new legislation, along with an improved understanding of the groundwater resource, should provide for continued sustainable use of this resource.

Table 5: Groundwater use, 2000–06
Year 2000 2001 2002 2003 2004 2005 2006
Water used (ML) 168 262 243 249 345 322 327

Source: TAMS

Water reuse

Water reuse is the use of non-potable water or treated effluent for uses other than drinking. It occurs at different scales, from the household garden to sourcing treated water from sewage treatment plants.

During the reporting period, regulatory reforms saw amendments to the Water and Sewerage Regulations 2001 to provide for separation of greywater in domestic premises to the edge of the floor slab. In addition, new developments are required to install 'provisional water pipes' to toilets, washing machines and an external point that will allow for future use of either greywater or rainwater. During this reporting period, no data were available on the use or uptake of greywater and associated technologies. While use of greywater is becoming more accepted and recognised as being capable of reducing water use in toilets and other domestic applications, it is anticipated that in the future more thought will be given to this topic.

On a larger scale, Table 6 presents water reuse from treated sewage in the ACT. The ACT has access to three sewage treatment plants that provide treated effluent to reuse schemes, Lower Molonglo Water Quality Control Centre, the Dairy Flat Sewage Treatment Plant and the Southwell Park Sewer Mining plant. The volume of treated water sourced from these plants represents approximately 7% of treated effluent. This is an increase of effluent reused since the previous reporting period of approximately 5%.

Expansion of these schemes could provide the ACT with some additional mains water savings. It is expected that in the future more information describing the potential for large-scale effluent schemes to contribute to the Territory's water efficiency targets will become available.

Table 6: Water reuse volumes (ML), 2003–04 to 2006–07
Facility 2003–04 2004–05 2005–06 2006–07
LMWQCC 1830.6 1634.8 1675.6 1583.9
Belconnen Golf Course 143.1 123.9 114.6 154.8
BRL Hardy 100.1 112.5 120.2 94.7
Southwell Park 20.4 29.4 16.4 25.8
North Canberra Effluent Reuse System 0.0 260.4 214.2 244.7
Outward Bound 0.3
Total 2094.3 2160.9 2141.0 2104.1

Note: LMWQCC = Lower Molonglo Water Quality Control Centre
Source: ActewAGL

Environmental flows

The term environmental flow refers to the release of water in a predetermined manner intended to mimic the natural hydrological pattern in regulated rivers. The natural hydrological pattern includes droughts, variability in flow (through random events) and large peak discharges in flooding events. Environmental flows are intended to remediate river ecosystems functionality in spite of the negative effects of flow regulation which, among other factors, reduce peak flood flows, provide less variability in flows and generally result in lower base flows.

In the ACT, where environmental flows are released from water supply reservoirs, it is crucial to find a balance between the needs of the upland river ecosystem and the operational capacity of the water supply.

The Environmental Protection Authority (TAMS), on advice from ActewAGL and research organisations, sets environmental flows based on statistical flow thresholds for the reaches of the Cotter River below the three water supply reservoirs (Corin, Bendora and Cotter). These are regulated through the Environmental Flow Guidelines, under the Water Resources Act 2007. They were developed in 1999 and revised in 2006. The updated guidelines recognise that during dry times, when Canberra's population faces temporary water restrictions, it is appropriate to reduce environmental flows. Special rules for drought periods have been specified, maintaining flows at a minimal level and allowing more water for domestic consumption. These rules have been applied during the reporting period.

Environmental flows are set for the Cotter River reaches between Corin Dam and Bendora Dam, between Bendora Dam and Cotter Dam, and below Cotter Dam. However, environmental flows from the upper reaches are effectively re-used and the only water lost to the urban water supply system due to environmental flow requirements is that required to be released from the Cotter Dam, and even this can potentially be captured by the ActewAGL pumps in the Murrumbidgee River at the Cotter Dam.

During this reporting period, due to the drought, a low environmental flow regime has been implemented. Table 7 illustrates the environmental flows under drought conditions. Environmental flow releases will be returned to 'normal' levels under the Guidelines when the storage levels increase and the temporary water restrictions are lifted.

Table 7: Water volume required for environmental flows (ML), 2003–04 to 2006–07
Flow 2003–04 2004–05 2005–06 2006–07
Cotter required environmental flow 16,431 73,65 6,580 3,603
Below Cotter Dam river flow 14,551 12,203 13,197 11,475

Source: TAMS and ActewAGL

During the reporting period, limited data were available on the effect of environmental flows on all but target species. Of the data available, the macroinvertebrate study undertaken by community and research groups indicates the adverse effect of the Corin, Bendora and Cotter dams at sites approximately 500 metres downstream of the dam walls. However, downstream there are no detectable adverse effects on the macroinvertebrates. In fact, in some seasons downstream of the dams, the results indicate the macroinvertebrate diversity is equivalent to reference stream conditions.

In response to the limited data available about the effect of environmental flows, the ACT Government has initiated a Commonwealth Government funded National Action Plan project delivering environmental flows to large biota. This project has two objectives:

  • Develop a knowledge base from which to achieve best outcomes for the aquatic ecosystem in the Cotter River catchment based on use of environmental flows (including use of multi-level off-takes to mitigate thermal pollution).
  • Develop a detailed understanding of the post-bushfire distribution of threatened and pest species in the lower Cotter River (includes status of Macquarie perch, two-spined blackfish and spiny crayfish populations in the heavily sedimented Cotter River).

Currently data are being analysed and a final report is being prepared. The project is to conclude on 30 June 2008.

In the ACT few, but emerging, data exist on the needs of individual species. Even less or no data exist at the scale of the ecosystem or catchment. Environmental flow management in the ACT provides the opportunity to study the effects of environmental flows in upland rivers with a broader integrative knowledge base at a wide range of scales, especially those relevant to the catchment and its management.

There is a lack of published data on the effect of environmental flows in the ACT on the environment. This data gap is not restricted to the ACT. While addressing the data gap is a challenge, particularly given the complexities associated with environmental flows in this region, it is one that is likely to be meet over time.

Water demand management

The pressure of the drought on water resources during the reporting period led to significant attention being paid to water demand management. This has been the case both at the ACT and national levels of government. Several strategies and key policy changes were developed to address water availability issues.

The National Scale: the ACT, the Murray–Darling Basin and the National Water Initiative

In terms of the Murray–Darling Basin, the ACT is a small jurisdiction in a large catchment with a diverse range of problems. The landscapes that comprise the Murray–Darling Basin create a range of social and environmental issues, some of which are not applicable to the ACT; for example, large-scale irrigation. Regardless of the broad range of issues within the Murray–Darling Basin, the ACT is part of several high-value Murray–Darling Basin catchments and is the largest urban centre.

The Territory's responsibility is exemplified by its support for, and commitment to, the Murray–Darling Basin Commission, particularly concerning crossborder issues such as water trading and the Murray–Darling Basin Cap. The cap is a limit on the volume of water that may be diverted from rivers for consumptive uses. During the last reporting period, the ACT committed to participating in the Murray–Darling Basin Cap. At the time of writing a draft ACT cap had been submitted to the Murray Darling Basin Commission.

On the national level, the Council of Australian Governments approved the National Water Initiative in 2004. The document encompasses a wide range of water management initiatives and encourages adoption of best-practice approaches to managing water in Australia.

The ACT is committed to implementing the initiative. The ACT Government's Think Water, act Water strategy, released in April 2004, encompasses and supports the objectives of the initiative.

ACT Water Resource Strategy

In response to the drought and consequent water availability issues, as well as future planning concerns and climate change, the ACT Government accelerated a host of future plans and in 2004 it released its water resource strategy: Think water, act water.

The strategy has six key objectives for managing the Territory's water resources, namely:

  • provide a long-term, reliable source of water for the ACT and region
  • increase the efficiency of water usage
  • promote development and implementation of an integrated regional approach to ACT–New South Wales crossborder water supply and management
  • protect the water quality in ACT rivers, lakes and aquifers, to maintain and enhance environmental, amenity, recreational and designated use values and to protect the health of people in the ACT and down river
  • facilitate incorporation of water sensitive urban design principals into urban, commercial and industrial development
  • promote and provide for community involvement and partnership in managing the ACT water resources strategy.

Importantly the strategy sets a measurable target of decreasing per capita mains water use by 12% or 71.60 GL by 2013 and by 25% or 77.44 GL by 2023. These targets are to be met through water efficiency measures to reduce use and mains water source substitution by water recycling and use of storm water, rainwater and recharging of aquifers.

In addition Think water, act water includes a second target focused on increasing the use of water sources other than the mains storages. The target is to increase the use of treated wastewater (reclaimed water) from approximately 5% in 2003 to 20% by 2013. The intention is for this target to be met by source substitution as part of the potable water reduction target. Other targets include limiting the amount of storm water flow from newly developed areas to the same amount that flowed before development; and managing the level of nutrients and sediments entering the ACT waterways to that of a well-managed rural landscape.

Annual monitoring of the Think water, act water strategy measures progress and effectiveness of the actions taken to save water. Table 8 illustrates water saved during the reporting period. The data indicate that during the reporting period the water restrictions, in addition to the Permanent Water Conservation Measures were the most effective water consumption reduction measures with other measures totalling approximately 20% of water saved. Future predictions estimate an increased water saving role for the water saving strategies known as Canberra Integrated Urban Waterways, Water Efficiency and Labelling Standards and Water Sensitive Urban Design. These strategies were in their formative stages during the reporting period.

Towards the end of the reporting period the Water Security Taskforce reviewed various options to diversify the water supply sources. This included examining the options of an enlarged Cotter Dam and a water purification plant.

Expanding water supply

Having access to sufficient drinking water was one of the key factors that determined the location of the ACT. This and the effective planning and management of water resources, has ensured that water supplies for the ACT and region are more than adequate for the wet and average years and are generally sufficient during short drought periods. Until recently it had been assumed by the ACT Government that further significant upgrades of the supply infrastructure would not be needed until around 2023. However, despite comprehensive planning, upgrades to supply infrastructure, and demand management initiatives that have been implemented in recent years, the extended period of unexpectedly low inflows has resulted in the need for the current review of the ACT and region's long-term water security.

In mid-2007, the ACT Government engaged the Water Security Taskforce and its Advisory Panel to provide advice on water security, in particular ActewAGL's Water2WATER proposal and its July 2007 recommendations to the government on water security for the ACT and region.

Table 8: Effect of water saving strategies (GL), 2003–04 to 2006–07
Water consumption 2003–04 2004–05 2005–06 2006–07
Expected natural consumption 66.10 66.78 67.41 68.05
Actual consumption 52.20 51.73 54.34 51.06
Actual total savings 13.90 15.05 13.07 16.99
Percentage savings 23% 19% 25%
Think water, act water water saving strategies
PWCM n/a 4.80 4.85 4.90
Information and awareness n/a 2.99 3.02 3.05
WELS n/a 0.00 0.08 0.16
WSUD n/a 0.23 0.41 0.51
New regulations n/a 0.11 0.15 0.18
Think water, act water residential programs
Watersmart Homes (indoor tune ups) n/a 0.05 0.12 0.15
Garden Smart (outdoor tune ups) n/a 0.02 0.04 0.06
Dual flash toilet rebate n/a 0.00 0.01 0.02
Showerhead rebate program n/a 0.01 0.18 0.18
Rainwater tank program n/a 0.07 0.10 0.10
Think water, Act water water saved (GL) 8.28 8.96 9.31

Notes: PWCM = Permanent Water Conservation Measures; WELS = Water Efficiency and Labelling Standards; WSUD = Water Sensitive Urban Design
Source: TAMS

Pricing

The pricing of water has changed significantly during the reporting period as water reform, availability and the real cost of water is realised at the tap. In February 1994, the Council of Australian Governments identified six major areas where the Australian water industry needed reform. Among these was water pricing. Following identification of reforms, a Council of Australian Governments agreement was reached that requires urban water prices to adopt consumption-based, full cost recovery pricing and removal or transparency of cross-subsidies. Prices are to reflect the volume of water supplied, encourage more economical water use and defer the need for costly infrastructure investments such as new dams.

The Independent Competition and Regulatory Commission is a statutory body set up to regulate prices, access to infrastructure services and other matters in relation to regulated industries and to investigate competitive neutrality complaints and government-regulated activities in the ACT. It is the body responsible for fixing the water tariff in the ACT. The Commission set out a price path to apply to water and wastewater tariffs from 1 July 2004 to 30 June 2008 and set within this is a water abstraction charge. The water abstraction charge is a government charge to cover the environmental costs of providing water services and includes a component to cover the scarcity value of water.

Table 9 presents the price of water and sewerage costs for the reporting period. During this period the fixed charge has been reduced to make way for increases in the volumetric price of water and increases in the water abstraction charge. The cost of sewage treatment has increased.

Introduction of volumetric pricing in early 1991 led to a 20% reduction in per capita water use. However, subsequent studies have shown that the amount of water used does not decrease substantially as the price rises. It is difficult to specify the effect of price increases on demand during the reporting period. This is an example of close monitoring of the future effect of water demand strategies being needed in order to justify future strategies.

Table 9: Water and sewerage costs, 2003–04 to 2007–08
Charge 2003–04 2004–05 2005–06 2006–07 2007–08
Fixed charge ($) 125.00 75.00 75.00 75.00 75.00
Step 1 (KL) 0 100 100 100 100
Step 1 ($) 0.00 0.52 0.58 0.66 0.78
Step 2 (KL) 175 300 300 300 300
Step 2 ($) 0.43 1.00 1.14 1.29 1.67
Price after step 2 ($) 1.05 1.35 1.53 1.74 2.57
WAC ($) 0.20 0.20 0.25 0.55 0.55
Sewerage charge ($) 354.20 375.32 389.00 389.80 413.76

Note: WAC = water abstraction charge
Source: ActewAGL website

Water efficiency incentives

During the reporting period the ACTEW Corporation, on behalf of the ACT Government, began delivering the Water Efficiency (Incentives) Program to move toward meeting the Territory's potable water targets. The program targets the residential, commercial, government and education sectors to encourage water savings through incentive rebates, audit recommendations and educational information and advice.

To further reduce the volume of water used, the ACT Government introduced a series of water efficiency incentives aimed at household use. Such schemes include the showerhead rebate which ceased in early 2006 due to the free availability of AAA rated showerheads.

Rebates on rainwater tanks saw several changes during the reporting period (Table 10). While the range of tank volume and rebate value were increased, a condition requiring connection to the laundry or toilet was added. This aim was to maximise tank use throughout the year as tank use for gardens has mainly occurred during the summer months. The effect of this policy decision was a reduction in the number of rebate approvals (Table 11).

Table 10: Rebates on rainwater tanks ($), 2003–04 to 2006–07
Total storage capacity
(litres)
2003–04
($)
2004–05
($)a
2005–06
($)c
2006–07
($)d
2,000–3,999 150 350b 550b
4,000–8,999 300 500b 700b
4,500–8,999 200
9,000 500 400 600b 800b

Notes: a An additional rebate of $150 was offered for the connection of the tank to the laundry or toilet.
b With internal connection.
c An additional rebate of $200 was offered for the internal connection of an existing rainwater tank.
d An additional rebate of $400 was offered for the internal connection of an existing rainwater tank.
Source: TAMS Rainwater tank database

Table 11: Rainwater tank rebate approvals, 2003–04 to 2006–07
2003–04 2004–05 2005–06 2006–07 Total
Total internal connection only rebate 0 2 8 9 19
Total no. of rebate 317 849 301 103 1,570
Total tank volume (ML) 1.00 5.50 2.15 0.89 9.54
Total water saved (ML/year)* 27 73 26 9 135

Note: Water saved is calculated based on 86 KL of savings per year per installation
Source: TAMS Rainwater tank database

Future water supply options

With an increasing population and the prospect of reduced inflows as a result of future drought or climate change, a key challenge in the medium- to long-term is construction of more or larger water supplies to meet demand. In keeping with the ACT Government's strategy on water resources, ActewAGL and the ACT Government have investigated a range of options to increase the capacity of supply to the ACT.

During the reporting period a range of options was investigated. Some include the Tennent Dam, Tantangara transfer, Murrumbidgee transfer, and Cotter Dam enlargement as water harvesting options from the catchments; and recycling of waters from the Lower Molonglo Water Quality Control Centre. However, following these investigations, the ACT Government established the Water Security Taskforce; the findings of which are summarised in the following 10 recommendations:

  • Cotter Reservoir to be enlarged by 2011. In doing this, the relevant recommendations made by the Advisory Panel were to be addressed.
  • Murrumbridgee–Googong transfer be progressed.
  • Arrangements for the Tantangara option be progressed, to secure additional water from a source not largely dependent on rainfall within the ACT.
  • Further consideration not be given to a water purification scheme until completion of further extensive analyses.
  • Additional greenhouse gas emissions associated with operating the water security projects be voluntarily offset.
  • Demand management incentives programs be continued to achieve the Think water, act water targets.
  • Extension of Permanent Water Conservation Measures be investigated.
  • Metering of water be improved in the ACT by ActewAGL; and ActewAGL be asked to implement a pilot smart metering program in the ACT, for commencement in 2008–09.
  • The Think water, act water strategy be updated.
  • Progress in implementing the water security program be monitored.

The ACT Government has adopted all recommendations.

Data sources

ACTEW Corporation and ActewAGL provided data on bulk water use, pricing and environmental flow data. Territory and Municipal Services provided on the water resource strategy, groundwater, pricing, water saving strategies and additional data on environmental flows. 

References

ACT Government 2004, Think Water Act Water. ACT Government, April 2004.

ACTEW 2005, Future Water Options for the ACT Region, Implementation Plan, ACTEW Corporation, April 2005.

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