DARWIN REGION WATER SUPPLY - STRATEGY 2013 - Power and Water ...
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POWER AND WATER CORPORATION
DARWIN REGION
WATER SUPPLY
2013
STRATEGYDarwin Region Water Supply Strategy #1080991/04-2015 powe r a n d wat e r co r p o rati o n
Darwin Region Water Supply Strategy i
Contents
1 EXECUTIVE SUMMARY................................................................................................................................1 3.7 Emergency Supply.............................................................................................................................. 18
1.1 Introduction............................................................................................................................................................1 3.8 Water Demand Trends. ............................................................................................................. 19
1.2 Water Supply Security and Sustainability............................................1 3.9 Water Supply Pricing..................................................................................................................... 20
1.2.1 Risk – Sustainability of Supply.................................................................1
4 WATER DEMAND FORECASTING................................................................................21
1.2.2 Mitigation – Sustainability of Supply......................................1
4.1 Introduction...................................................................................................................................................... 21
1.2.3 Risk – Security of Supply.......................................................................................1
1.2.4 Mitigation – Security of Supply.............................................................2 4.2 Methodology.................................................................................................................................................. 22
1.3 Immediate Supply Risks – by 2015......................................................................2 4.3 Bulk Water Demand Projections......................................................................... 22
1.3.1 Risk........................................................................................................................................................................2 4.4 Adopted Growth Rates............................................................................................................. 22
1.3.2 Mitigation.............................................................................................................................................2 4.4.1 Base Case.......................................................................................................................................... 22
1.4 Short Term Supply Risks – by 2020......................................................................2 4.4.2 Modelled Loads................................................................................................................... 23
1.4.1 Risk........................................................................................................................................................................2 4.4.3 Alternative Demand Growth Scenarios........................ 23
1.4.2 Mitigation.............................................................................................................................................2 4.5 Future Improvements to Demand Modelling....................... 23
1.5 Medium Term Supply Risks – Beyond 2020......................................2 5 FUTURE WATER CHALLENGES......................................................................................... 24
1.5.1 Risk........................................................................................................................................................................2 5.1 Climate Change........................................................................................................................................ 24
1.5.2 Mitigation.............................................................................................................................................2
5.2 Greenhouse Gas Emissions............................................................................................ 25
1.6 Planning Uncertainties..................................................................................................................3
1.6.1 Risk........................................................................................................................................................................3 6 DEMAND REDUCTION STRATEGIES.................................................................. 26
1.6.2 Mitigation.............................................................................................................................................3 6.1 Urban Water Use................................................................................................................................... 26
1.7 Catchment Risks...........................................................................................................................................3 6.1.1 End Water Use....................................................................................................................... 27
1.7.1 Risk........................................................................................................................................................................3 6.1.2 Benchmarking....................................................................................................................... 28
1.7.2 Mitigation.............................................................................................................................................3 6.2 Community Attitudes to Water Use........................................................... 28
1.8 Summary of Key Activities......................................................................................................4 6.2.1 Key findings................................................................................................................................. 28
6.2.2 Power and Water’s Response to the Survey.......... 29
GLOSSARY OF TERMS..........................................................................................................................................................6
6.3 Drivers for Demand Management................................................................. 29
2 INTRODUCTION. .......................................................................................................................................................7
6.4 Demand and Supply Management Initiatives. ................... 29
2.1 Background Information............................................................................................................7 6.4.1 Darwin Water Smart............................................................................................... 30
2.2 Key Objectives....................................................................................................................................................7 6.4.2 Non-revenue Water................................................................................................... 32
2.3 Previous Long-term Planning...........................................................................................7 6.4.3 Water Tariff Pricing Signals....................................................................... 32
2.4 Strategy Development....................................................................................................................7 6.4.4 Sustaining Water Demand Savings....................................... 32
2.5 Regulatory Environment.............................................................................................................7 7 FUTURE WATER SOURCE OPTIONS....................................................................33
3 CURRENT WATER SYSTEM REVIEW.......................................................................... 9 7.1 History........................................................................................................................................................................... 33
3.1 Water Sources....................................................................................................................................................9 7.2 Immediate Action to Address
3.1.1 Darwin River Dam......................................................................................................... 10 Emergency Supply Shortfall.......................................................................................... 33
3.1.2 Manton Dam. .......................................................................................................................... 10 7.3 Source Augmentation in the Short Term......................................... 34
3.1.3 McMinns and Howard East Borefields. .......................... 10 7.3.1 Further Development of .
3.2 Water treatment.................................................................................................................................... 12 the Howard East Borefield. ........................................................................ 34
3.2.1 Water Quality.......................................................................................................................... 12 7.3.2 Manton Dam Return to Service...................................................... 34
3.3 Distribution Network.................................................................................................................. 12 7.4 Strauss Water Storage and Treatment Facility..................... 34
3.4 Recent Water Supply Trends......................................................................................... 14 7.5 Source Augmentation Options for
the Medium Term................................................................................................................................ 36
3.4.1 Meteorological Influences – El Niño .
and La Niña............................................................................................................................14 7.5.1 Future Dam Sites............................................................................................................. 36
3.4.2 Rainfall. .................................................................................................................................................. 14 7.5.2 Augmentation of Manton Dam’s Storage............... 40
3.4.3 Demand. ............................................................................................................................................. 15 7.5.3 Adelaide River Off-stream .
Water Storage Scheme. ..................................................................................... 41
3.4.4 Water Storage........................................................................................................................ 16
7.5.4 Desalination............................................................................................................................... 42
3.4.5 Water Conservation.................................................................................................. 16
7.6 Alternative Supply Options. ........................................................................................... 42
3.5 Level of Service Objectives................................................................................................ 17
7.6.1 Water Sensitive Urban Design.......................................................... 42
3.6 System Yield...................................................................................................................................................... 18
7.6.2 Rainwater Tanks................................................................................................................. 42
3.6.1 Headroom Requirement................................................................................. 18
7.6.3 Greywater Reuse.............................................................................................................. 42
3.6.2 Target System Yield..................................................................................................... 18
7.6.4 Stormwater Reuse........................................................................................................ 43
7.6.5 Recycled Wastewater............................................................................................. 43
power an d wat er corporationii Darwin Region Water Supply Strategy
7.7 Evaporation Reduction Technology. ............................................................. 43 Figure 16: Factors Influencing Water Demand............................................... 21
7.8 Excluded Options.................................................................................................................................. 44 Figure 17: Darwin Region – Projected Bulk .
7.8.1 Darwin River Dam Storage Augmentation............ 44 Water Demand............................................................................................................................. 22
7.8.2 Darwin River Dam – Further Extraction
Figure 18: Demand Projection Based on .
Supported by Water Treatment. ..................................................... 44
‘High Growth’ Scenario............................................................................................... 23
7.8.3 Lambell’s Borefield....................................................................................................... 44
7.8.4 Continued Development of the . Figure 19: Darwin Region Water Supply .
Howard East Borefield......................................................................................... 44 Consumption Segmentation......................................................................... 26
7.8.5 Alternative Dam Sites........................................................................................... 44 Figure 20: Darwin Average Water End Use.............................................................. 26
7.8.6 Existing Dams and Lakes............................................................................... 46
Figure 21: Darwin Seasonal Water End Use.......................................................... 27
7.8.7 Hanna’s Pool on the Finniss River............................................... 46
Figure 22: Average Annual Residential .
8 DEVELOPMENT OF PLANS.......................................................................................................... 47 Water Supplied (kL/ property)..................................................................... 28
8.1 Demand/Supply Model.......................................................................................................... 47
Figure 23: Existing and Planned Emergency .
8.2 Demand Driven Water Source Supply Capability..................................................................................................................... 33
Development Programme................................................................................................ 47
Figure 24: Site Map for Strauss Water .
8.3 Capital Expenditure Programme........................................................................ 49
Treatment Facility................................................................................................................... 35
9 MANAGEMENT OF RISK AND UNCERTAINTY............................50
Figure 25: Plan of Future Dam Site Options .
9.1 Water Demand Growth.......................................................................................................... 50 for the Darwin Region................................................................................................... 37
9.2 Impacts of Climate Change........................................................................................... 50
Figure 26: Proposed Upper Adelaide River Dam Site .
9.3 Impact of Government Policy.................................................................................... 50 and Affected Land Parcels..................................................................................... 38
9.4 Catchment Risks..................................................................................................................................... 50
Figure 27: Manton Dam – Potential Storage .
10 STAKEHOLDER CONSULTATION. .................................................................................51 Augmentation................................................................................................................................ 40
11 REFERENCES...................................................................................................................................................................52 Figure 28: Adelaide River Off-stream Water .
Storage Scheme.......................................................................................................................... 41
APPENDIX 1: LAND TENURE AND LAND ZONING MAPS
FOR DARWIN REGION WATER SUPPLY CATCHMENTS.............. 53 Figure 29: Previously Considered Dam Sites......................................................... 45
Figure 30: Current Water Source .
LIST OF FIGURES
Development Programme................................................................................... 48
Figure 1: Application of Level of Service Objectives to
Darwin River Dam........................................................................................................................1 Figure 31: Alternative Programme – For Planning .
and Design Purposes....................................................................................................... 48
Figure 2: Current Water Source Development Programme......... 4
Figure 3: Alternative Programme – For . LIST OF TABLES
Planning and Design Purposes........................................................................5 Table 1: Summary of Source Availability.....................................................................2
Figure 4: Locality Plan of the Darwin Region.........................................................8 Table 2: Summary of Key Activities – Darwin .
Region Water Supply Strategy...........................................................................5
Figure 5: Water Sources for the Darwin .
Region Water Supply System...............................................................................9 Table 3: Darwin Region Water Strategy Key Objectives.............7
Figure 6: Overview of the Darwin Region Water . Table 4: Howard East and McMinns Borefield .
Supply Distribution System.............................................................................. 13 Production Bore Details and Extraction Limits...... 11
Figure 7: Darwin Region Long Term Rainfall Trend............................. 14 Table 5: Summary of Source Availability............................................................... 12
Figure 8: Darwin River Dam Catchment Rainfall................................... 14 Table 6: Annual Water Demand Variability..................................................... 15
Figure 9: Residential Water Use................................................................................................... 15 Table 7: Summary of Reliability of Supply .
and System Yield....................................................................................................................... 19
Figure 10: Darwin River Dam Storage .
Levels - 1978 – 2013.......................................................................................................... 16 Table 8: Base Case Population Growth to 2030.................................... 22
Figure 11: Application of Level of Service Objectives . Table 9: Major Industrial Development .
to Darwin River Dam....................................................................................................... 18 in the Darwin Region. ..................................................................................................... 23
Figure 12: Darwin Region Water Consumption . Table 10: Climate Change Predictions for .
by Customer Type. .................................................................................................................. 19 the Darwin Region................................................................................................................ 24
Figure 13: Darwin Region Water Consumption . Table 11: Previous Water Efficiency Initiatives.............................................. 30
Trend by Customer Type........................................................................................... 19
Table 12: Darwin Water Smart Initiatives............................................................... 31
Figure 14: Darwin Region Water Demand – .
Table 13: Capital Investment Programme – Water .
Seasonal Impacts.................................................................................................................... 20
Source Development Projects...................................................................... 49
Figure 15: Residential Water Tariff Comparison............................................ 20
powe r a n d wat e r co r p o rati o nDarwin Region Water Supply Strategy 1
1 Executive summary
1.1 Introduction 1.2.1 Risk – Sustainability of Supply Using Power and Water’s water
resource modelling, the yields of the
The Darwin Region Water Supply A sustained series of poor wet seasons
existing water sources have been
Strategy – hereafter called the could mean insufficient recharge to
calculated for each of the level-of
Strategy – details the Power and Water Darwin River Dam, causing water levels
service objectives. In this way, the
Corporation’s plan to balance demand to fall steadily in the region’s principal
total system yield is determined, in
for water with the capability of supply water supply source. This would place
turn informing the programmed
to a planning horizon of 2030. The the continuity of supply at risk.
development of water sources.
Strategy covers the capacity and make-
up of the current water supply system, 1.2.2 Mitigation – Sustainability The target system yield incorporates
forecast growth in demand, existing of Supply 10 per cent headroom between annual
and proposed initiatives for demand demand for water and capability of
To ensure appropriate water security,
management, future water source supply. The headroom provision buffers
planning and management objectives
options, and a programme for the large annual fluctuations in observed
that define a level of service for the
development of new water sources. (historical) demand (+/- 10 per cent),
Darwin region water supply have
which are being driven by variable
The Darwin region water supply been developed. The level-of-service
annual rainfall and wet season periods
system currently sources water from objectives provide for two levels of
in the Darwin region. The headroom
the Darwin River Dam (85 per cent) reliability of water supply: 95 per cent
also caters for any significant and
and the McMinns and Howard East unrestricted demand reliability (water
unplanned step increases in demand
Borefields (15 per cent). Water is not restrictions 1 in 20 years), and 99 per
arising from potential rapid industrial
currently sourced from Manton Dam cent restricted demand reliability
development in the region.
owing to infrastructure constraints, (severe water restrictions 1 in 100
water quality challenges and recreation years). The Strategy incorporates Figure 1 (below) illustrates the
on the reservoir. a drought-response plan, which application of the level of service
manages periods of low inflows . objectives to Darwin River Dam.
1.2 Water Supply Security and to the system, and an emergency-
Sustainability response plan, to deal with . 1.2.3 Risk – Security of Supply
prolonged severe drought.
Darwin region water supply is strongly In the event of an unexpected loss
influenced by climate, including the The level-of-service objectives include a of supply from the region’s principal
seasonal nature of rainfall in the wet/ four-stage regime of water restrictions. water resource, Darwin River Dam,
dry tropics, the variability of rainfall The regime provides Power and Water water supply to the Darwin region
from year to year (which affects annual with a way to manage demand during would be greatly affected. Loss of
water demand and inflows to Darwin periods of low inflows to the region’s supply could be caused by, for .
River Dam), and the forecast impacts reservoirs owing to drought, or in the example, contamination, .
of climate change, particularly a likely event of a delay in the programmed equipment failure or terrorism.
increase in evapotranspiration. development of new water sources.
Figure 1:
Application of Level of Service
Objectives to Darwin River Dam
Relative Frequency of
level Volume Description Demand Reliability trigger
Working (m AHD) (GL) (%) (%) (%) (1 in X years)
Volume 45.86 320 100 FSL 100
39 100 31 Stage 1 90 95 20
Stage 1
37 65 20 Stage 2 80 not defined not defined
Drought (1 in 20 years)
Stage 2 35.5 44.5 14 Stage 3 65 not defined not defined
Response
Stage 3
Reserve 34 28 9 Stage 4 50 99 100
Stage 4
Contingency (1 in 100 years) 32 15 5 Dead
Storage
Provides 2 years supply Storage
at stage 4 restrictions Dead
Storage 28 0 0 Empty
FSL = Full Supply Level
power an d wat er corporation2 Darwin Region Water Supply Strategy
1.2.4 Mitigation – Security of Supply Table 1 (below) shows how Darwin 1.4.2 Mitigation
region water supply’s existing sources
In the event that supply from Darwin To support continued growth in the
of water contribute to the current total
River Dam becomes unavailable, Power region while deferring the need for
system yield.
and Water aims to provide an alternate significant capital investment in
supply from a source independent The current target system yield, new water sources, Power and Water
of Darwin River Dam. Such a source which incorporates the 10 per cent has developed an accelerated and
would supply the region over the headroom requirement, is 47,864 ML/ expanded demand management
short term and during the emergency. yr, representing an immediate shortfall programme called ‘Living Water Smart’.
Groundwater from the McMinns of 5,084 ML/yr.
Living Water Smart aims to reduce
and Howard East Borefields could be
water demand by 10,000 ML/yr by
used to diversify sources of supply 1.3.2 Mitigation
2018. The programme will do this
in this way. Furthermore, and in the
Planned further development of the by improving asset management
absence of an alternative supply that is
Howard East Borefield in 2014/15 (reducing water losses and managing
independent of Darwin River Dam, the
is designed to address the lack of system pressure) and through a
groundwater supply at the borefields
redundancy, enabling the borefield to comprehensive programme of .
must have adequate redundancy. This
provide sufficient emergency supply water conservation.
means the borefields should meet an
capacity for a 2030 planning horizon.
‘n-2’ reliability criterion, whereby the Achieving Living Water Smart’s savings
The connection of Manton Dam,
groundwater supply would continue targets will defer the need to connect
planned for 2025 will further augment
to meet the supply diversity objective new sources of water in the Darwin
the emergency supply at that time.
even in the event that the two . region by up to seven years (to 2025).
highest-yielding bores fail. Enhancing the redundancy of the
The next step in Power and Water’s
Howard East Borefield will also allow
water source development programme
1.3 Immediate Supply Risks Power and Water to reliably access
is the return to service of Manton Dam,
– by 2015 its existing licensed groundwater
which will provide additional supply
allocation. This will increase the
of 7,400 ML/yr to the Darwin region.
1.3.1 Risk total amount of water available for
Reconnecting Manton Dam to the
extraction from connected sources
The existing groundwater supply system will also significantly enhance
to 45,200 ML/yr, again reducing the
fails to meet the requirement for the emergency supply capacity.
shortfall in the water supply system.
borefield redundancy. Consequently
Planning and design for the return to
the supply fails to meet Power and
1.4 Short Term Supply Risks service of Manton Dam is continuing,
Water’s supply diversity objective
– by 2020 and can be fast-tracked should Living
for the current demand. Further, the
Water Smart’s water demand savings
lack of redundancy means Power and
1.4.1 Risk targets not be achieved. Additionally,
Water is unable to make full use of the
Power and Water could introduce .
groundwater allocation for which it . Population-driven growth in demand,
low-level water restrictions to achieve
is licensed. as well as incremental increases
the targeted reduction in demand.
associated with large industrial
The water supply system’s yield is
developments in the Darwin region,
equal to the combined yields from 1.5 Medium Term Supply
is driving the planning for additional
connected water sources, taking into Risks – Beyond 2020
sources of water in the short term.
account infrastructure and licensing
constraints. The current water supply 1.5.1 Risk
system yield is 42,780 ML/yr, compared
Further organic demand growth and
with a total system demand in
continued industrial expansion will
2012/13 of 42,805 ML.
require the development of additional
Table 1: sources of water in the medium
Summary of Source Availability term. Climate change is forecast
Available extraction to impact on supply by increasing
Licenced extraction [limited by infrastructure or yield] evapotranspiration, which will lead
Source (ML/yr) (ML/yr) to reduced inflows to reservoirs and
decreasing yields.
McMinns and Howard
East Borefields 8,420 6,000
1.5.2 Mitigation
Darwin River Dam 49,100 36,780
Power and Water’s demand
Manton Dam 7,300 0
management strategy provides for
TOTAL 64,820 42,780 further water conservation initiatives
beyond 2020.
Beyond the return to service of Manton
Dam, planning and investigations
powe r a n d wat e r co r p o rati o nDarwin Region Water Supply Strategy 3
are underway for an additional major Power and Water’s water demand/ 1.7.2 Mitigation
source of water for the Darwin region supply model is ‘reset’ every year
Power and Water has developed
water supply. Options currently being after the end of the financial year,
a Catchments and Water Source
considered include: so that demand is forecast from the
Protection Strategy to support the
• An in-stream dam (on the upper . most recent demand data. Demand
proactive management and protection
Adelaide River); modelling and forecasting are being
of its water supply catchments.
improved through interrogation of
• An off-stream storage (in the water consumption data by customer Wellhead protection zones have
Marrakai region), filled with water type, and by analysing impacts on been established around production
harvested from flood flows in the demand from seasonal and annual bores to help reduce the risk of
Adelaide River; weather fluctuations. contamination. In areas where rural
• Augmentation of Manton . residential development has occurred
Dam’s storage; Five-yearly reviews of yield are
adjacent to existing bores, Power and
undertaken for the sources comprising
• Desalination; and/or Water works with the Department of
the Darwin region’s water supply. The
• A range of decentralised integrated Health to ensure the installation of
reviews use updated local and regional
water management solutions, site-appropriate wastewater treatment
meteorological information and data,
including rainwater tanks, greywater and disposal systems.
and factor in the latest information
reuse and wastewater recycling to on climate change. Climate change There may be an opportunity to
reduce the reliance on the potable adaptation strategies for water partially shift Power and Water’s
water system for non-potable uses. agencies are being developed at a regular extraction of water from the
National level, and Power and Water is McMinn’s Borefield to Howard East
1.6 Planning Uncertainties monitoring developments in this area. Borefield, further reducing the risk
of contamination. The shift could
1.6.1 Risk The Northern Territory Government
accompany the planned further
manages the sustainable use of the
There are a number of inherent development of the Howard East
region’s water resources through a
uncertainties associated with water Borefileld, which aims to enhance
water allocation planning process.
supply planning for a 20-year period: redundancy in Power and Water’s
Power and Water is a member of a
groundwater supply. However, the
• Water demand growth is subject number of water allocation advisory
McMinn’s Borefield will remain a
to a range of influences, including committees, and also actively consults
critical component of Power and
population growth, economic with the Department of Land Resource
Water’s groundwater supply capability.
activity and the impact of . Management in its planning for the
major projects; development of new water sources. Power and Water regularly reviews its
catchment management activities to
• Climate change is forecast to have
1.7 Catchment Risks protect source water quality. Some of
a significant impact on yields
the most important activities include
available from the region’s water
1.7.1 Risk managing fire, weeds and .
supply sources, including increasing
feral animals, and catchment .
evapotranspiration and reducing A number of significant catchment-
security and surveillance.
runoff and recharge, however a great related risks have the potential to
deal of uncertainty remains as to impact on the sources of Darwin A water treatment plant will be
the rate of change and the level of region’s water supply. developed as part of returning Manton
impact; and Dam to service. In time, the water
In the McMinns Borefield, land
• Regulation of water extraction/ treatment plant could be expanded
adjacent to Power and Water’s water
abstraction is an area of uncertainty, to also treat water from Darwin River
supply bores has been developed .
as contemporary approaches to Dam, providing additional measures
for rural residential and horticultural
water management in the Northern to reduce risk where undertaken in
land uses. These land uses pose a .
Territory are currently being support of Power and Water’s drinking
risk of contamination to the public
developed and implemented. water management objectives.
water supply.
1.6.2 Mitigation Conditions in the region’s surface
water catchments also pose a number
Forecasting growth in water demand
of significant risks to water quality in
requires analysing a number of factors,
reservoirs. These risks include illegal
including: Historical trends, population
access to the catchment, erosion and
growth forecasts from the Department
flood damage, bush fires, feral animals
of Treasury and Finance and the
and weeds.
Australian Bureau of Statistics, and
forecasts of major urban and industry
development from the Department .
of Business and the Land .
Development Corporation.
power an d wat er corporation4 Darwin Region Water Supply Strategy
1.8 Summary of Key Activities As shown, returning Manton Dam Power and Water recognises the
to service significantly augments reductions in water demand
Figure 2 (below) represents the
the capacity of the water supply targeted under Living Water Smart
current water source development
system. Before this time however, the are ambitious, and contingent upon
programme, and is an output from
modelling suggests water restrictions sustained community and Government
Power and Water’s demand/supply
may be required in some years. On support. As a prudent way to manage
modelling. The programme reflects
occasion, the demand for water will this risk, Power and Water is continuing
key planning assumptions, including
approach the capacity of the system to the planning and design work for
achieving water demand targets set
supply it, and will encroach upon the Manton Dam’s return to service and
down under Living Water Smart.
10 per cent headroom requirement. for future sources of water so this
programme can be fast-tracked should
growth in demand outpace demand
management efforts.
Figure 2:
Current Water Source Development Programme
Industrial Step Demands Demand Projection Based On PWC BASE - 1.45 %
Residential Demand Management: -20.60% Total by 2018 Historical Demand
Industrial Demand Management: -21.60% Total by 2018 Supply Capacity
Climate Change Impact on Demand: +2.66% Total by 2030 10% headroom requirement infringed
Climate Change Impact on Supply: -10.00% Total by 2030 Augmentation Dates
100,000
Howard East Borefield -
Further Development
Return to Service
Darwin River Dam -
Howard East Borefield
Manton Dam -
Consumption (ML/annum)
Raise FSL
50,000
2001/02
2010/11
2014/15
2025/26
0
1999/00
2004/05
2009/10
2014/15
2019/20
2024/25
2029/30
Year
Figure 3 (on the following page) Table 2 (on the following page) formal update and public release every
shows an alternative programme, summarises the key activities to be five years.
which has been prepared assuming delivered under the Strategy to a 2030
Power and Water will review the initial
50 per cent of the Living Water Smart planning horizon. The activities include
results of Living Water Smart in late
demand-management targets are providing additional supply capacity
2015. The review will determine when
achieved. This represents the earliest to manage demand for water and to
Manton Dam should be returned to
achievable programme, considering the engage with the community around
service and whether low level water
significant number of engineering and issues of water supply and demand
restrictions are needed to achieve
environmental studies and approvals management. It is intended that the
water demand savings targets.
that are required, and making allowance Strategy be reviewed annually, with a
for construction times.
powe r a n d wat e r co r p o rati o nDarwin Region Water Supply Strategy 5
Figure 3:
Alternative Programme – For Planning and Design Purposes
Industrial Step Demands Demand Projection Based On PWC BASE - 1.45 %
Residential Demand Management: -10.30% Total by 2018 Historical Demand
Industrial Demand Management: -10.70% Total by 2018 Supply Capacity
Climate Change Impact on Demand: +2.66% Total by 2030 10% headroom requirement infringed
Climate Change Impact on Supply: -10.00% Total by 2030 Augmentation Dates
100,000
Next Water
Howard East Borefield -
Source
Further Development
Return to Service
Manton Dam -
Darwin River Dam -
Consumption (ML/annum)
Howard East Borefield
Raise FSL
50,000
2001/02
2010/11
2014/15
2017/18
2025/26
0
1999/00
2004/05
2009/10
2014/15
2019/20
2024/25
2029/30
Year
Table 2:
Summary of Key Activities - Darwin Region Water Supply Strategy
Timeframe Key Activities Outcomes
By 2015 Implement Living Water Smart Reduce per capita water consumption
Embed water conservative community culture
Engage with community around water supply and demand issues Community input to next issue of Darwin
Region Water Supply Strategy
Further development of the Howard East Borefield Increased emergency supply capability
Increased reliability of extracting existing
licensed groundwater allocation
Undertake environmental and engineering studies on a range of . Identify preferred medium-term water supply
medium-term water supply options for the Darwin region option for the Darwin region
By 2016 Review initial results of Living Water Smart and refine demand Review timing for return to service of Manton
management initiatives Dam and assess the need for water restrictions
to achieve water demand savings
By 2020 Review and refine demand management strategy Reduce per capita water consumption
Sustain water conservative community culture
Publish next issue of the Darwin Region Water Supply Strategy Darwin Region Water Supply Strategy responds
to community expectations
By 2025 Return Manton Dam to service Increased supply capability
Enhanced emergency supply capability
Improved diversity of supply
Beyond Continue to implement demand management action plan Reduce per capita water consumption
2025 Develop medium term water supply source Increased supply capability
Enhanced emergency supply capability
Improved diversity of supply
power an d wat er corporation6 Darwin Region Water Supply Strategy
GLOSSARY OF TERMS
Augmentation Recycled water
Works required to increase . Water from sewage or industrial
water supply processes that is treated to appropriate
standards for its intended use
Aquifer
An underground layer of water- Level of service objectives
bearing rock or materials from which An adopted standard of water .
groundwater may be extracted. supply that endeavours to achieve
supply outcomes expected by the
Catchment.
community, by using a range of
An area of land where run-off enters a
measures including the desirable
particular river system or reservoir
maximum frequency, duration and
Demand management severity of water restrictions
Initiatives that endeavour to reduce
Surface water
water consumption and encourage
Water stored or transported above
more efficient water use and reduce
ground (i.e. in lakes, rivers, dams)
water losses from the system
System yield
Drought Response Plans
A figure derived from models that
Short term action plans that provide
refers to the volume of water that
effective responses to deal with the
can be harvested from a water supply
occurrence of droughts
system in order to achieve the adopted
Groundwater standard of service
All subsurface water, generally
Unrestricted water demand
occupying pore spaces and .
The total volume of water used by
fractures in rock and soil
consumers during periods without
Megalitre (ML) water restrictions
1,000,000 litres
Water demand
Potable. The average annual water demand
Suitable for drinking based on water consumption and
population projections
powe r a n d wat e r co r p o rati o nDarwin Region Water Supply Strategy 7
2 Introduction
2.1 Background Information Table 3:
Darwin Region Water Strategy Key Objectives
The development of the Darwin Region
Water Supply Strategy demonstrates Key Objectives:
the commitment of Power and Water 1. Providing sustainable and economical long term water resource planning
to more efficient urban water use, for the Darwin Region;
and to identifying supply options that
2. Establishing a balance between sustainable supply options and demand
will maintain an appropriate balance
management initiatives;
between urban water supply and
demand for the next 20 years. 3. Reducing bulk raw water demand, and per capita water consumption;
The strategy identifies programmed 4. Maximising the utilisation of existing infrastructure and already .
water source development projects for disturbed natural water systems prior to developing new water sources;
the Darwin region, as well as exploring 5. Assessing climate change impacts in the development of future supply
options for the development of future and demand scenarios;
water sources. 6. Identifying new and alternative local water resource options .
for consideration;
2.2 Key Objectives
7. Integrating alternative water supply options into future water .
The strategy aims to achieve supply planning;
sustainable urban water management 8. Ensuring water resource planning is undertaken in a transparent and
in the short and long term through a auditable framework; and
range of measures focussed on:
9. Engaging local communities in planning for long term sustainability of
• Securing water supplies their water resources.
• Reducing water demand
• Balancing water supply with growth 2.3 Previous Long-term Planning Sewerage, Power and Water
in demand Corporation, 2010.
Long-term water supply planning is
• Supplying water in a financially • Survey outcomes, Community
an ongoing process requiring regular
responsible manner. Attitudes to Water Use, Power and
review. This document will be reviewed
and updated every five years. Water Corporation, 2006.
• Framework for Urban Water Resource
Previous long-term planning reports
Planning, Water Services Association
that were used to develop this strategy
of Australia (WSAA), 2005.
include:
• Guidelines for the Development of
• Darwin Water Story, 2005 a Water Supply Demand Strategy,
• Darwin Bulk Water Strategy, 2004 Department of Sustainability and
• Water Resources for the Greater Environment (DSE), Victoria, 2005.
Darwin Area - Darwin Water • Darwin Water Story, Power and Water
Resources Strategy, 1999 Corporation, 2005.
• Darwin Rural Area South Further information on references is
- Water Supply Development provided in Section 11 REFERENCES.
Master Plan, 1996
• Darwin Regional Water Supply and 2.5 Regulatory Environment
Land Management Strategy, 1988
Power and Water is a Government
Further information on references is Owned Corporation. The multi-utility
provided in Section 11 REFERENCES. is responsible for the provision of
water supply, sewerage and electricity
2.4 Strategy Development services and a five-member Board
steers the organisation.
The development and presentation of
the Strategy is informed by a number The Northern Territory Treasurer is
of documents, including: the Shareholding Minister, and Power
• Planning Guidelines for Water and Water reports to the Minister for
Supply and Sewerage, Queensland Essential Services (as the portfolio
Department of Environment and Minister). A three-member Utilities
Resource Management, 2010. Commission acts as regulator for
Government. The Northern Territory
• Power and Water Corporation
Government sets utility tariffs in
Supplements for the Planning
consultation with Power and Water.
Guidelines for Water Supply and
power an d wat er corporation8 Darwin Region Water Supply Strategy
Water resources in the Northern in accordance with the National Water The water allocation planning
Territory are regulated by the Initiative and the NT Water Act. Water process has commenced in the
Department of Land Resources and Allocation Plans have been created, or Koolpinyah (Howard East) Aquifer. The
Management (DLRM). Extraction from are underway or proposed, in places groundwater resource is considered to
surface or groundwater resources for where current or potential water be under stress and extraction may be
Public Water Supply requires licensing use could pose a risk to the ongoing exceeding sustainable levels. The Water
under the Water Act. Extraction availability and health of the resource. Allocation Planning process is expected
licenses are granted by the Controller to limit extraction to sustainable levels
The Water Act specifies that extraction
of Water Resources, who must take and achieve an equitable share of the
licenses are to be issued for a
a number of factors into account resource between consumptive users,
maximum of 10 years and can be
when issuing a licence, including whilst providing for environmental and
varied at any time. Upon the Minister’s
environmental and cultural needs. The cultural water requirements.
advice, a licence can be granted for a
Department of Health regulates the
longer period and a number of current
public health aspects of public drinking
Power and Water licenses, including
water supplies.
those for Darwin, have been granted
Water allocations, or entitlements, are for 50 years. However where Water
provided through Water Allocation Allocation Plans are in place, the
Plans, which are developed by DLRM, licenses have been issued for 10 years.
Figure 4:
Locality Plan of the Darwin Region
ARAFU RA SEA
MELVILLE BATHURST
ISLAND ISLAND
COX PENINSULA
DARWIN
BATCHELOR ADELAIDE RIVER
TIMOR SEA
PINE CREEK
Groote
Eylandt
KATHERINE
AY
HIGHW
GULF
MATARANKA ROPER
OF
CARPENTARIA
AY
W
GH
HI
TIMBER CREEK
BORROLOOLA
Y
HW
STUART
E
IN
NT
BU
TABLELANDS
AD
RO
BUNTINE ELLIOTT
T
VER
CAL
HIGHW
B A R K L Y
AY
T A B L E L A N D
HIGHWAY
BARKLY HIG
HW
AY
TENNANT
powe r a n d wat e r co r p o rati o n
CREEKDarwin Region Water Supply Strategy 9
3 Current water system review
3.1 Water Sources The Darwin region’s water supply to McMinns Storage and Transfer
system obtains its water from both Station, where the water is blended
Darwin is located in the wet-dry
surface water sources (via dams) and and piped to Darwin, Palmerston and
tropics of Northern Australia, with
groundwater (via bores). The great the outer Darwin area.
high average temperatures and high
proportion (approximately 85 per
year-round evapotranspiration, a Power and Water has developed .
cent) of the Darwin region’s water
monsoonal wet season lasting four to a Water Source Protection Strategy .
is currently sourced from Darwin
five months, and a largely rain-free dry to support the proactive management
River Dam, with an important
season lasting seven to eight months and protection of its water supply
supplementary supply extracted
on average. catchments.
from the McMinns and Howard East
Borefields. These two sources are piped
Figure 5:
Water Sources for the Darwin Region Water Supply System
DARWIN
PALMERSTON MCMINNS AND
HOWARD EAST
BOREFIELDS
Darwin
River Dam Manton Dam
power an d wat er corporation10 Darwin Region Water Supply Strategy
3.1.1 Darwin River Dam 3.1.2 Manton Dam The majority of the catchment is
freehold land owned by Power and
Darwin River Dam was constructed in Manton Dam was constructed in the
Water and leased to the Conservation
1972 about 50 km south of Darwin. early 1940s by the Department of
Land Corporation. The catchment
Darwin River Dam is a 518m-long Defence to provide a reliable source of
is contained within the Coomalie
earth embankment dam, with an water for Darwin during World War II.
area and identified in the Coomalie
unregulated 265m wide spillway. Located approximately 50km southeast
Planning Concepts and Land Use
of Darwin, Manton Dam, with a storage
In 2010, Power and Water completed Objectives (2000), on unzoned land.
capacity of 14,000 ML, was the city’s
an upgrade of the embankment and
primary source of water until the Land tenure and land zoning plans .
raised the spillway at Darwin River
commissioning of Darwin River Dam for Manton Dam are at Appendix 1:
Dam to increase the full supply level .
in 1972. Since that time Manton Dam Land Tenure And Land Zoning .
by 1.3m. The augmentation increased
has been maintained as an emergency Maps For Darwin Region Water .
the yield of the dam by approximately
water supply source for the Darwin Supply Catchments.
20 per cent and resulted in a storage
Region water supply system.
capacity of 320,000 ML.
3.1.3 McMinns and
Power and Water is licensed to extract
Power and Water is currently licensed Howard East Borefields
7,300 ML/yr from Manton Dam. The
to extract 49,100 ML/yr from Darwin
supply from Manton is not currently The McMinns Borefield, 30km East
River Dam, however its yield has
used as an operational source of water South East of Darwin in Howard
recently been assessed as 36,780 ML/
due to infrastructure constraints and Springs, was established in the 1960s
yr, after the latest of a series of regular
water quality challenges, including on the Koolpinyah dolomite aquifer.
five-yearly reviews of yield. Extraction
recreational use of the dam. Manton
beyond the yield is possible, but this Stage 1 of the Howard East Borefield,
Dam’s yield has recently been assessed
will reduce the level of service offered, the first of four planned stages, was
as able to provide a 7,400 ML/yr net
resulting in an increased likelihood of commissioned in 2001 to supplement
contribution to the Darwin Region’s
water restrictions for the community. the existing supply from the McMinns
water supply.
This issue is further explored in Section Borefield.
3.6 Level of Service. In an emergency, Power and Water
The Howard East and McMinns
could deliver up to 10 ML/day from
Borefields can theoretically provide up
3.1.1.1 Darwin River Dam Catchment Manton Dam to the McMinns Transfer
to 20 per cent of the Darwin region’s
Station to supplement the water
Darwin River Dam catchment is current demand requirements, but,
supply system. However the water
operated as a closed catchment, being due to infrastructure constraints
quality would not comply with the
predominantly undeveloped and with including a lack of redundancy in the
Australian Drinking Water Guidelines
restricted public access. The catchment borefields, current supply is limited to
without treatment. Therefore the use
management plan aims to control around 15 per cent of Darwin’s water
of Manton Dam as a limited short-
environmental threats, including wild supply. Importantly, the Howard East
term emergency supply during a crisis
fires and weeds, and recognises the and McMinns Borefields are an integral
such as a cyclone event or failure of
catchment’s environmental values, part of the diversification, security
the Darwin River Dam supply system
being a refuge for native flora and and emergency supply aspects of the
is possible, but undesirable in the
fauna, including migratory and local Darwin Region Water Supply Strategy.
absence of water treatment facilities.
bird species, as well as its role as a
Power and Water is currently licenced
public water supply source.
3.1.2.1 Manton Dam Catchment to extract 8,420 ML/yr from the six
The majority of the land is freehold and production bores in the Howard East
Manton Dam catchment was operated
owned by Power and Water with most and McMinns Borefields as detailed in
as a closed catchment until the late
of the balance falling within the Finniss Table 4 (on the following page).
1980s when Government directed it
River Land Trust. The Northern portion
be opened up for recreational use by
of the catchment is zoned Water
the community. Today water skiers,
Management under the NT Planning
anglers, picnickers and day trippers visit
Scheme, identified in the Litchfield area
the dam on a regular basis and it has
zone plan. The Southern portion of
become a popular freshwater recreation
the catchment is contained within the
destination for the local populace.
Coomalie area and identified in .
the Coomalie Planning Concepts and The recreational use of the dam is
Land Use Objectives (2000), . managed by the Parks and Wildlife
on unzoned land. Commission, who are also responsible
for catchment management. Power
Land tenure and land zoning plans .
and Water remains responsible for .
for Darwin River Dam are at Appendix
the maintenance of the water .
1: Land Tenure And Land Zoning .
supply infrastructure.
Maps For Darwin Region Water .
Supply Catchments.
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