Commonwealth environmental water use
options 2013-14:
Murrumbidgee River Valley
1
Cover image credit: Murrumbidgee River valley. Photo by Andrew Lowes © CEWO
Acknowledgement of the Traditional Owners of the Murray-Darling Basin
The Commonwealth Environmental Water Office respectfully acknowledges the Traditional
Owners, their Elders past and present, their Nations of the Murray– Darling Basin, and their
cultural, social, environmental, spiritual and economic connection to their lands and waters.
This report should be cited as ‘Commonwealth environmental water use options 2013–14: Murrumbidgee River Valley’.
Published by the Commonwealth Environmental Water Holder for the Australian Government.
© Commonwealth of Australia 2013.
This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by
any process without prior written permission from the Commonwealth. Requests and enquiries concerning
reproduction and rights should be addressed to Department of Sustainability, Environment, Water, Populations and
Communities, Public Affairs, GPO Box 787 Canberra ACT 2601 or email public.affairs@environment.gov.au
Information presented in this document may be copied for personal use or published for education purposes, provided
that any extracts are fully acknowledged. The views and opinions expressed in this publication are those of the authors
and do not necessarily reflect those of the Australian Government or the Minister for Sustainability, Environment, Water,
Population and Communities. While reasonable efforts have been made to ensure that the contents of this publication
are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the
contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use
of, or reliance on, the contents of this publication
2
Commonwealth environmental water use options
2013–14: Murrumbidgee River Valley
Table of contents
1. Introduction ........................................................................................................ 5
2. Context for water use in 2013–14 in the Murrumbidgee River Valley ........... 6
2.1.
Delivering environmental water to the Murrumbidgee River Valley ............................... 6
2.2.
Operational and management considerations for 2013–14 in the Murrumbidgee River
Valley ........................................................................................................................................... 7
2.3.
Valley condition ......................................................................................................................... 9
3. Water availability ............................................................................................. 12
3.1.
Commonwealth environmental water holdings in the Murrumbidgee River Valley for
2013-14 ....................................................................................................................................... 12
3.2.
Other sources of environmental water allocations .......................................................... 12
3.3.
Natural or unregulated flows and planned environmental water ................................ 13
4. Planning for water use in the Murrumbidgee River Valley in 2013-14 ........ 14
4.1.
Planning for a range of inflows in 2013-14 .......................................................................... 14
4.2.
Implementing watering actions throughout the year ...................................................... 14
5. Water use options and the Basin Plan’s environmental watering plan
objectives ......................................................................................................... 16
5.1.
Demonstrating how Commonwealth environmental water in 2013–14 will contribute to
the Basin Plan’s environmental watering plan objectives – Murrumbidgee River Valley
..................................................................................................................................................... 16
6. Water use options for 2013–14 ........................................................................ 18
6.1.
Watering options...................................................................................................................... 18
6.2.
Assessment of environmental watering options ................................................................ 39
7. Accounting for the use of Commonwealth environmental water .............. 40
7.1.
Water use accounting ............................................................................................................ 40
7.2.
Operational monitoring .......................................................................................................... 40
8. Partnerships ...................................................................................................... 41
9. Bibliography ..................................................................................................... 42
3
List of Figures
Figure 1: Map of the Murrumbidgee River Valley. ................................................................................... 7
Figure 2: How inflows may vary and impact on water resource availability over the course of
2013–14 in the Murrumbidgee River Valley, from a starting point of Moderate to High resource
availability. ..................................................................................................................................................... 14
List of Tables
Table 1: Operational considerations for the Murrumbidgee River Valley in 2013–14. ...................... 8
Table 2: Commonwealth environmental water holdings in the Murrumbidgee River Valley as at
30 April 2013................................................................................................................................................... 12
Table 3: Other potential sources of environmental water in the Murrumbidgee River Valley for
2013–14 as at 10 May 2013. ........................................................................................................................ 13
Table 4: Expected outcomes from the use of Commonwealth environmental water in the
Murrumbidgee River Valley. ....................................................................................................................... 17
Table 5: Summary of water use options for the Murrumbidgee River Valley. .................................. 19
4
1. Introduction
This document is designed to be read in conjunction with the Commonwealth environmental
water use options 2013–14: Planning approach, which outlines the approach to planning for
the use of Commonwealth environmental water this coming water year. The planning
document provides the context for key aspects of the approach including determining
resource availability, the expected outcomes from watering actions and the relationship
between the function of the Commonwealth Environmental Water Office (the Office) and the
Basin Plan.
This document outlines watering options for the use of Commonwealth environmental water in
the Murrumbidgee River Valley this year. The options, which describe potential watering
actions, series of actions, or watering strategies, do not represent a commitment for water use.
Consistent with the Office’s framework, decisions to make water available for any of the
potential options will be subject to an assessment against five published criteria (available from
the Office’s website) and seasonal, operational and management considerations at the time
of the action. All relevant watering actions will be assessed to ensure the best possible use of
environmental water within the relevant planning area and across the Murray-Darling Basin
and having regard to the Murray-Darling Basin Authority’s Basin annual environmental watering
priorities, once published.
5
2. Context for water use in 2013–14 in the
Murrumbidgee River Valley
2.1.
Delivering environmental water to the Murrumbidgee River Valley
Most of the flow in the Murrumbidgee River comes from the upper portion of the catchment,
originating from the upper Murrumbidgee and the main tributary rivers—Yass, Molonglo,
Queanbeyan, Bredbo, Numeralla, Cotter, Goodradigbee and Tumut (Kingsford & Thomas
2001) (Figure 1). The Murrumbidgee River is heavily regulated with 26 dams and weirs and over
10,000 km of irrigation canals (Kingsford 2003). Storages include those in the Snowy Mountain
Hydro-electric Scheme, those forming the Australian Capital Territory Water Supply System and
the major New South Wales irrigation dams (Blowering Dam and Burrinjuck Dam; CSIRO 2008).
Flows from the Tumut River are augmented by approximately 550 GL of water that is transferred
annually to Blowering Dam from southern-flowing rivers in the Snowy River Catchment via the
Snowy Mountain Hydro-electric Scheme.
There are seven main weirs downstream of Blowering and Burrinjuck dams used to manage
water levels for diversion—Berembed, Yanco, Gogeldrie, Hay, Maude, Redbank and Balranald
weirs. The weirs contain relatively small storage volumes (1–13 GL) and have limited capacity
for re-regulation of flow. There is also an off river en-route storage (Tombullen) with a capacity
of 11 GL that offers some re-regulation opportunity.
The Murrumbidgee Irrigation Area and Coleambally Irrigation Area are located downstream of
Wagga Wagga and account for approximately three quarters of the irrigation diversions in the
catchment. The Murrumbidgee Irrigation Area is supplied by the Main Canal, which diverts
water from the Berembed Weir pool, and Sturt Canal, which diverts water from the Gogeldrie
Weir pool. The Coleambally Irrigation Area is also supplied by a canal that diverts water from
the Gogeldrie Weir Pool. Flows into the Yanco-Billabong Creek system are regulated by Yanco
Weir. Diversions into the Nimmie-Caira portion of the Lowbidgee Floodplain are taken from the
Maude Weir pool, whilst diversions into South and North Redbank are taken from the Redbank
Weir Pool.
The Blowering and Burrinjuck dams, seven weirs and Tombullen Storage are operated by State
Water Corporation to meet irrigation and other customer orders. Since the weirs and Tombullen
have relatively small storages, most orders are supplied by releases from either of the two dams
and customers are required to place orders sufficiently early to allow for the travel time to their
diversion structure, plus one day processing time. Any transmission losses between the dams
and the customer’s diversion structure are met by State Water Corporation.
Environmental assets that are able to be watered by releases from the major storages and inchannel flows include the river channel itself and low-lying wetlands and creek systems with
commence to flow thresholds occurring below bankfull height. Such environmental assets
include the Mid-Murrumbidgee wetlands, areas of the Yanco-Billabong Creek system and Old
Man Creek system that fall inside the Murrumbidgee River water management area. Some offchannel assets such as those within the Murrumbidgee Irrigation Area, Coleambally Irrigation
Area and Lower Murrumbidgee Floodplain can be watered using irrigation delivery
infrastructure. Pumping water directly to wetlands is possible in some cases, but this practice
can be expensive, is often inefficient and lacks the hydrological connectivity sought by
watering wetland assets.
Environmental water delivery in the Murrumbidgee is facilitated by the New South Wales Office
of Environment and Heritage on behalf of the Commonwealth Environmental Water Office
and in most cases, delivery is undertaken and managed by State Water Corporation.
6
Where targeted environmental assets are off the main State Water Corporation managed
system, the NSW Office of Environment and Heritage (including the National Parks and Wildlife
Service), landholders and irrigation corporations undertake the physical management of the
delivery. The NSW Office of Water and the State Water Corporation charge usage fees on
licensed water delivered in the state. This applies equally to environmental and irrigation water.
Figure 1: Map of the Murrumbidgee River Valley.
2.2.
Operational and management considerations for 2013–14 in the
Murrumbidgee River Valley
The delivery of environmental water in the Murrumbidgee River Valley is currently constrained
by the release capacities from storages, channel capacities, and system constraints. Burrinjuck
and Blowering dams have storage capacities of 1,028 and 1,628 GL respectively with
maximum outlet capacities (when full) of 29,100 and 21,300 ML/day. However, the Water
Sharing Plan for the Murrumbidgee River Regulated Water Source limits flows in the Tumut River
to 9,000 ML/day at Oddy’s Bridge and 9,300 ML/day at Tumut. The Water Sharing Plan also
limits discharge in the Murrumbidgee River at the Tenandra Bridge at Mundarlo, between
Gundagai and Wagga Wagga, to below 32,000 ML/day (although recent changes to the
ratings table for Gundagai mean that this may be lowered to around 29,500 ML/day). NSW
State Water works approvals prohibit releases beyond these constraints.
Operational considerations such as delivery methods, opportunities, constraints and risks will
differ depending on the inflow scenario and are summarised in Table 1. In Table 1, operational
considerations are assessed against inflow scenarios which are represented by annual
exceedance probability (AEP), that is, the number of years that a given inflow is equalled or
exceeded, expressed as a percentage.
Throughout the year operational and management considerations will be addressed as
decisions are taken to make water available for use and as these decisions are implemented.
7
This will include refining the ecological objectives, assessing operational feasibility and
potential risks and the ongoing monitoring of the seasonal outlook and river conditions.
Table 1: Operational considerations for the Murrumbidgee River Valley in 2013–14.
Inflow scenario
Very low
(90%
AEP1)
Low (75%
AEP)
Moderate
(50%
AEP)
High
(25%
AEP)
Very high
(10%
AEP)
Opportunities
Manage the recession of naturally
occurring high flows to provide for a
more natural flow pattern.
Use environmental water in
conjunction with, or to maximise the
environmental benefit of, naturally
occurring river flows.
Pumping and water diversion via
regulating structures to key sites may
be considered depending on an
assessment of the action and the
level of river flows.
Constraints
Natural flows meet environmental
flow requirements, reducing the need
for and effectiveness of
environmental water.
Delivery options are limited due to
high unregulated flows resulting in
reduced channel capacity, limiting
the operation of river infrastructure
and inhibiting additional releases
from storages.
Flows in the Murrumbidgee River at
Gundagai are limited to less than
32,0002 ML/day to prevent inundation
of Tenandra Bridge on the Mundarlo
Road near Gundagai.
Flows in Tumut River are limited to less
than 9,000 ML/day at Oddy’s Bridge
and 9,300 ML/day at Tumut to
minimise bank erosion.
Percentages refer to the probability of exceedance based on historical inflows for the
catchment, i.e. there is a 90 per cent chance that actual flows will be greater than that
amount.
1
Recent changes to the ratings table for Gundagai mean that this may be lowered to around
29,500 ML/day.
2
8
Inflow scenario
Very low
(90%
AEP1)
Low (75%
AEP)
Moderate
(50%
AEP)
High
(25%
AEP)
Very high
(10%
AEP)
Yanco Weir has a maximum diversion
capacity of 1,400 ML/day to Yanco
Creek. Flows over ~2,000 ML/day may
cause floodplain inundation.
Release capacities of storages may
constrain the magnitude of
augmentation.
Risks*
The provision of Commonwealth
environmental water must consider
potential inundation impacts to
property and infrastructure.
Environmental flows inundate
floodplain and wetland habitat that is
rich in organic matter, creating
adverse water quality conditions.
Environmental flows promote
spawning and recruitment by exotic
invasive species.
Significant natural rainfall occurs on
an environmental watering action
resulting in unintended third party
impacts.
Return flows are re-regulated for
irrigation purposes, limiting
environmental benefits of upstream
environmental flow releases for the
lower Murrumbidgee floodplain and
lower Murray River.
* See Section 6.2 for more information on risk management.
2.3.
Valley condition
Low rainfall and inflows between 2000 and 2010 meant many ecological assets in the
Murrumbidgee catchment went without water for a prolonged time. During the drought,
environmental water was released by the NSW state government to protect key environmental
assets in the Lower Murrumbidgee Floodplain and Murrumbidgee Irrigation Area.
Commonwealth environmental water has been delivered in conjunction with water from the
NSW OEH to a number of assets in the Murrumbidgee catchment since 2009. The ecological
impacts of the drought may have a lasting impact on assets in the Murrumbidgee. During the
2010–11 and 2011–12 water years, the Murrumbidgee catchment, like much of the MurrayDarling Basin, experienced relatively wet conditions. Inflows triggered extensive flooding across
the Murrumbidgee River catchment during the spring and summer of 2010–11 and early
autumn in 2012. Peak flows in the Murrumbidgee River during the flood in March–April 2012
reached 345,000 ML/day at Gundagai. Commonwealth environmental water was not
delivered during these flood events.
The 2012–13 water year saw a return to drier than average conditions in the Murrumbidgee
catchment. Rainfall was below average across the entire valley while above average
9
temperatures were experienced, particularly throughout summer and into autumn. Water in
Burrinjuck Dam fell from almost full in October 2012 to below 40% in March 2013. Similarly, water
in Blowering Dam fell from more than 90% full in December 2012 to less than 60% full in March
2013.
Preliminary findings indicate positive ecological benefits from these natural flow events and the
return of water across the Murrumbidgee catchment since the drought. The conditions of key
assets in the Murrumbidgee catchment are discussed below.
Murrumbidgee River channel
The overall health of the Murrumbidgee River ecosystem was rated as “poor” by the
Sustainable Rivers Audit carried out during 2008–2010 (Davies et al. 2011). During the summer of
2010–11 and the autumn of 2012 sections of the lower Murrumbidgee were affected by
blackwater, which resulted in low levels of dissolved oxygen and caused fish deaths. This
blackwater resulted from the large natural floods which mobilised built-up organic matter, such
as leaf litter, from floodplains to the river channel. The breakdown of this organic matter lowers
oxygen levels.
Environmental watering of the Murrumbidgee River channel below Darlington Point in late 2012
is expected to have benefited fish recruitment, helping communities to recover from the
impacts of prolonged drought and blackwater. Preliminary findings have indicated several
species of fish, including Murray cod, Australian smelt, and golden perch were spawning
during the period of environmental watering.
Mid-Murrumbidgee Floodplain Wetlands
The Mid-Murrumbidgee Floodplain contains an assemblage of wetlands with variable flood
histories (Page et al. 2005). Regulation has halved the frequency of overbank flooding in this
section of the Murrumbidgee (Page et al. 2005), with heavy rainfall or large environmental
flows now required to inundate these floodplain wetlands (NSW Office of Environment and
Heritage 2012). At the end of the drought, many of the Mid-Murrumbidgee Wetlands had not
been inundated for 5–14 years (NSW Office of Environment and Heritage 2012, Wassens et al.
2012). The subsequent condition of the inundation-dependent vegetation of the wetlands was
critical and declining in 2009 (SKM 2011). Successive flooding since 2010 has resulted in
improved condition of the Mid-Murrumbidgee Wetlands; however, the system is still recovering
(Wassens et al. 2012). Overall, vegetation in these wetlands is in poorer condition than in 2000
(NSW Office of Environment and Heritage 2012) with recovery more apparent in wetlands that
had been dry for only 3–5 years than those that had been dry for longer (Wassens et al. 2012).
The Mid-Murrumbidgee Wetlands dried considerably over summer 2012–13. In December 2012,
many key wetlands had less than 15 cm of water remaining. Fewer numbers of frogs and the
senescence of wetland aquatic vegetation were also recorded, having declined substantially
since earlier surveys following the return of water to the wetlands.
Lowbidgee wetlands
Diversion structures have created substantial differences in the watering history (and hence
condition) of the different wetlands on the Lowbidgee Floodplain. Some parts of the floodplain
were severely affected by drought, whereas other sections survived relatively well, mostly
because of stock and domestic flows and environmental flows to support breeding habitat for
waterbirds (NSW Office of Environment and Heritage 2012). Flooding in 2010–11 inundated
nearly all of the Lowbidgee floodplain, enabling severely degraded areas to start recovering
from prolonged drying (NSW Office of Environment and Heritage 2012). Some areas remained
inundated for a prolonged time and were beginning to show signs of stress caused by
overwatering. These areas have since dried.
Regulation, floodplain diversion structures, and the construction of the Balranald-Ivanhoe Road
have meant that until 2011 several ephemeral lakes and wetlands that were once part of the
10
Lower Murrumbidgee Floodplain had not flooded in more than 100 years (NSW Office of
Environment and Heritage 2012). The construction of re-diversion structures, combined with
landholders entering into complementary land management arrangements, saw
environmental water delivered to these lakes and wetlands between 2011–13. The restoration
of these assets will provide broader basin benefits such as improved drought refuge and
expanding the Lowbidgee Floodplain habitat for threatened species. Findings from monitoring
from 2011 to 2013 indicate positive ecosystem responses to inundation despite the lengthy time
since they last received water. Responses include regrowth on surviving trees, germination of
new saplings, and occupation of wetland habitat by 47 species of waterbirds including three
threatened species (blue billed duck - Oxyura australis, freckled duck - Stictonetta naevosa
and painted snipe - Rostratula australis).
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3. Water availability
3.1.
Commonwealth environmental water holdings in the Murrumbidgee
River Valley for 2013-14
Commonwealth environmental water holdings available for use in 2013–14 in the
Murrumbidgee River Valley are shown in Table 2 below.
Table 2: Commonwealth environmental water holdings in the Murrumbidgee River Valley as at
30 April 2013.
Entitlement type
Entitlement held
(GL)
Long-term
average annual
yield (GL)
Estimated
carryover from
2012–13 (GL)2
Forecast water
availability for
2013–14 (GL)3
Murrumbidgee
(high security)
4.2
4.0
N/A
157-212
Murrumbidgee
(general
security)
200.1
128.1
45.5
Murrumbidgee
(conveyance)
7.7
7.3
0
Murrumbidgee
(supplementary)
20.8
2.9
N/A
Up to 20.8
Total –
Murrumbidgee
232.9
142.3
45.5
157-2124
Total – Southern
Connected
Basin1
1,110.6
915.8
150-175
1,147-1,5274
Notes:
1. The southern connected basin includes the Murrumbidgee, Murray, Lower Darling,
Goulburn, Campaspe (excluding Coliban) and Loddon entitlements.
2. Future decisions about use, transfers and the ability to deliver already approved actions will
affect carryover from 2012-13.
3. Forecasts are based on the best available information including State forecasts and
historical inflow scenarios. Forecasts include carryover from 2012-13. Forecasts for regulated
catchments are given to the nearest whole gigalitre except where the entitlement held by
the Commonwealth is below 1 GL.
4. These figures do not include supplementary, unregulated or ground water accruals in the
southern connected basin. Total forecast water available in the southern connected basin
does not include allocation in spillable water accounts in Victoria.
The full list of Commonwealth environmental water holdings can be found at
www.environment.gov.au/ewater/about/holdings.html and is updated monthly. A portfolio
management statement for the Murrumbidgee River Valley is available at
www.environment.gov.au/ewater/publications/index.html.
3.2.
Other sources of environmental water allocations
Other sources of environmental water that may be used to complement Commonwealth
environmental water delivery in the Murrumbidgee River Valley include water held by the
Living Murray Program and the NSW Office of Environment and Heritage.
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Table 3: Other potential sources of environmental water in the Murrumbidgee River Valley for
2013–14 as at 10 May 2013.
Source
Management Authority
Entitlement
Environment Entitlement - The
Living Murray Program
Murray-Darling Basin Authority
81.9 GL of Murrumbidgee
general security entitlement.
Environmental Water
Allowance
NSW Office of Environment
and Heritage
Water volumes accrue
according to complex rules
set out in the Murrumbidgee
Water Sharing Plan. The NSW
Office of Environment and
Heritage estimate
approximately 63 GL will be
available for use from the
allowance early in 2013–14.
NSW licensed entitlement
NSW Office of Environment
and Heritage
27.7 GL of general security
entitlement.
5.7 GL of supplementary
access entitlement.
5.9 GL of unregulated
entitlement.
Yanga Lowbidgee
entitlement
NSW Parks and Wildlife
Service
2.9 GL of general security
entitlement (however, NPWS
notes usually not available for
use).
155 GL of Lowbidgee
supplementary access
entitlement.
3.3.
Natural or unregulated flows and planned environmental water
In addition to water entitlements held by environmental water holders, environmental
demands may also be met via natural or unregulated flows and water provided for the
environment under rules in state water plans (referred to as ‘planned environmental water’).
The Water Sharing Plan for the Murrumbidgee Regulated River Water Source (2003) establishes
releases of planned environmental water (under Part 3, Clause 15) under operating rules for
Burrinjuck and Blowering dams.


Transparent releases:
o
Transparent releases from Blowering Dam to the Tumut River are equal to
560 ML/day plus any water use expected to occur between the dam and the
confluence with the Murrumbidgee River. When inflows fall below 560 ML/day,
release volumes are equal to inflows in addition to expected use.
o
Transparent releases from Burrinjuck Dam are the lesser of either the volume of
inflows to the dam over the previous 24 hours or 615 ML.
Translucent releases:
o
Translucent releases are made from Burrinjuck Dam on each day between 22 April
and 21 October. Daily release volumes are calculated based on catchment
conditions and storage volumes in Lake Burrinjuck.
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4. Planning for water use in the
Murrumbidgee River Valley in 2013-14
4.1.
Planning for a range of inflows in 2013-14
In addition to influencing opportunities, constraints and risks in relation to environmental
watering (see Table 1), inflows are a primary driver of resource availability. Resource availability
also reflects a combination of the allocations available to the Commonwealth Environmental
Water Holder (Section 3.1 above) and other environmental water holders (Section 3.2) as well
as natural or unregulated flows and planned environmental water (Section 3.3).
Given the variable rainfall experienced across the Basin, inflows are difficult to accurately
forecast. As shown in Table 2, carryover from 2012–13 for the southern connected basin is likely
to be in the range of approximately 150-175 GL, with forecast early season allocations (up to
31 July 2014) likely to be in the order of 350–675 GL, giving a total allocation range of
approximately 500–850 GL available for use in early 2013–14.
Consideration of this allocation range relative to the total entitlement volume (Table 2) and the
full range of inflows that may be possible suggests that resource availability early in 2013–14
may be moderate to high. From this starting point, the full range of possible inflows suggest that
resource availability over the course of the year could be between low and very high, and
unlikely to become very low (Figure 2). As such, the water use options described in Section 6
have been developed for a range of resource availability between low and very high.
Figure 2: How inflows may vary and impact on water resource availability over the course of
2013–14 in the Murrumbidgee River Valley, from a starting point of Moderate to High resource
availability.
4.2.
Implementing watering actions throughout the year
Resource availability will change over the course of 2013–14 as new allocation
announcements are made and water is used or traded. Climatic conditions will also affect the
potential for inflows. The Office will regularly review allocations against environmental
14
entitlements and seasonal streamflow forecasts over the course of the year to assess resource
availability.
This assessment, along with up-to-date information on environmental needs and the
operational and management conditions (Section 2) will allow the watering options in
Section 6 to be refined for implementation as required.
15
5. Water use options and the Basin Plan’s
environmental watering plan objectives
5.1.
Demonstrating how Commonwealth environmental water in 2013–14 will
contribute to the Basin Plan’s environmental watering plan objectives –
Murrumbidgee River Valley
Commonwealth environmental water use options for the Murrumbidgee River Valley in 2013–14
include the following two flow types:

base flows

freshes.
These flow types are illustrated in Figure 3 of the document Commonwealth environmental
water use options 2013-14: Planning approach.
Wetlands are also expected to be inundated.
The ecological response from delivering Commonwealth environmental water is reflected in
the expected outcomes.
The Commonwealth Environmental Water Office (the Office) has used the best available
science to determine how the expected outcomes of Commonwealth environmental water
contribute towards the objectives of the Basin Plan’s environmental watering plan.
Table 4 shows the expected outcomes that may be derived from Commonwealth
environmental watering using different flow types in the Murrumbidgee River Valley and the
relevant Basin Plan objectives.
16
Table 4: Expected outcomes from the use of Commonwealth environmental water in the
Murrumbidgee River Valley.
Flow Type
Expected outcomes
for 2013–14
Contributions to
longer term outcomes
Contribution to the
following Basin Plan
objective
Base flows
Avoidance
Population resilience
Resilience
Freshes
End of system flows
Connectivity
Ecosystem function
Base flows and
freshes
Within ecosystem
diversity
Landscape
ecosystem diversity
Biodiversity
Vegetation condition
and reproduction
Landscape
vegetation diversity
Vegetation
recruitment and
extent
Fish reproduction
Fish condition
Landscape fish
diversity
Waterbird survival
and condition
Landscape bird
diversity
Waterbird
reproduction
Waterbird fledging
Other vertebrate
condition
Other vertebrates
Other vertebrate
reproduction
Hydrological
connectivity
Connectivity
Ecosystem function
Biotic dispersal
Sediment transport
Primary production
Nutrient and carbon
cycling
Refuge
Recovery
Resilience
Chemical
Water quality
Resistance
Dissolved organic
carbon
Dissolved oxygen
Algal blooms
Biological
17
6. Water use options for 2013–14
6.1.
Watering options
Potential watering options for 2013–14 have been developed for the Murrumbidgee River
Valley, which reflect the approach to supply Commonwealth environmental water to
contribute to the overall environmental objectives under the Basin Plan’s environmental
watering plan.
The NSW Office of Environment and Heritage develop annual environmental watering plans for
the Murrumbidgee. The Commonwealth’s water use options are developed utilising plans
made by the NSW Office of Environment and Heritage and other information in the context of
supplying water to meet environmental demands. The focus of Commonwealth environmental
watering in the Murrumbidgee is to achieve outcomes at local, catchment and Basin scales.
These watering options have been designed to specifically enable the scaling of watering
actions across several potential inflow scenarios. This provides flexibility for water use to best
complement natural inflows.
Broadly, the aim of Commonwealth environmental watering in the Murrumbidgee River Valley
during 2013–14 will be to support the on-going environmental recovery that commenced
following the breaking of the drought (see Section 2.3). For some parts of the system, this will
mean providing river flows to support fauna recruitment in wetlands, the riparian zone and on
floodplains. For other parts of the system, this may mean making decisions not to provide water
to sites that require a drying phase.
Any volumes described in the options tables below are approximations only. The final volume
of Commonwealth environmental water made available will depend on river conditions at the
time of use, other environmental water contributions and in consideration of Basin-wide needs.
The water use options identified do not represent a commitment for use, nor do they reflect all
the possible water use options available. Additional water use options may be identified
throughout the water year. The Office welcomes information from the community on how
environmental water can best be used and managed. If you have any comments or
suggestions, please call 1800 218 478 or send an email to: ewater@environment.gov.au
18
Table 5: Summary of water use options for the Murrumbidgee River Valley.
Applicable level(s)
of resource
availability
Very Low
Low
Moderate
High
Very High
(see Section 4)
Option 1 – MidMurrumbidgee
River Wetlands
Contribute to river flows (fresh) and inundation of fringing wetlands to
continue recent improvements in wetland vegetation condition, and to
provide habitat to support survival and maintain the condition of waterbirds
and native aquatic biota (including fish, turtles, frogs and
macroinvertebrates).
Option unlikely to be pursued under this resource
availability.
Option 2 – MidMurrumbidgee
Wetlands
(infrastructure
assisted delivery)
Contribute to wetland inundation, using existing water delivery
infrastructure, to refill low-lying wetlands in the Mid-Murrumbidgee
Floodplain to provide habitat to support survival and maintain the condition
of waterbirds and native aquatic biota (including fish, turtles, frogs and
macroinvertebrates).
Option unlikely to be pursued under this resource
availability.
Option 3 –
Murrumbidgee
River fish pulse
(targeting large
and mediumbodied fish)
Contribute to river flows (high season base flows and an extended fresh) to promote movement and reproduction of large and
medium bodied fish in the middle and lower reaches of the Murrumbidgee River. The option would also aim to promote
reproduction, larval dispersal and survival through zooplankton production and, dependant on the peak flow of the event,
reconnect low-lying wetlands and allow fish movement into, and out of, these wetlands.
Option 4 –
Murrumbidgee
River fish pulse
(targeting smallbodied fish)
Contribute to river flows (multiple small freshes) to promote movement and
reproduction of small-bodied fish in the middle reaches of the
Murrumbidgee River. The option would also aim to promote reproduction,
larval dispersal and survival through zooplankton production.
Option 5 –
Restoring natural
flow variability
Option 6 –
Lowbidgee –
Option unlikely to be pursued under this resource
availability.
Contribute to river flows (baseflow and freshes) to the Murrumbidgee River channel, Yanco-Colombo-Billabong Creek system
and/or Old Man Creek system to restore natural events that are truncated by river regulation and/or extraction.
Contribute to river flows (fresh) using regulators to inundate wetlands in the North Redbank system, South Redbank (Yanga),
Nimmie-Caira and Fiddlers-Uara systems to maintain and improve wetland vegetation diversity and condition, and provide
19
wetlands in Yanga,
North Redbank,
Nimmie-Caira and
Fiddlers-Uara
Creek system
habitat to support survival and maintain the condition of native fish, waterbirds, and other aquatic vertebrates (e.g. frogs).
Option 7 –
Wetlands west of
the North Redbank
Channel
Contribute to inundation of wetlands and lakes located at the western edge of the Lowbidgee Floodplain (northwest of
Balranald and west of the North Redbank Channel) to promote continued recovery of riparian and wetland vegetation
communities, and to provide habitat for waterbirds and native aquatic fauna.
Option 8 –
Contingency to
support significant
bird or other
aquatic native
vertebrate
breeding event in
wetlands
Maintain wetland water levels and acceptable levels of water quality to support the completion of a significant breeding event
of birds or other native aquatic vertebrates in wetlands. This contingency is not to trigger a breeding event but for use when a
breeding event is already underway but considered in danger of failure due to drying.
Option 9 –
Murrumbidgee
River Fish Refuge
(contingency for
adverse water
quality issues)
Provide localised
refuge habitat for fish
and aquatic biota
during an adverse
water quality event.
The trigger for this
option would be a
drying down that
creates an adverse
water quality issue in
the lower catchment.
Option 10 – Silver
Pines anabranches
and Wetlands
Option unlikely to be pursued under this resource
availability.
Provide localised refuge habitat for fish and
aquatic biota during an adverse water quality
event. The trigger for this option would be a
natural flooding event that creates an adverse
water quality issue in the lower catchment.
To maintain river red gum and other wetland vegetation by reconnecting and refilling the anabranch
creeks and lagoons on the property ‘Silver Pines’ in the Yanco Creek system.
Option unlikely to be
pursued under this
resource availability.
Note: Under certain resource availabilities, options may not be pursued for a variety of reasons including that environmental demand may be met by
unregulated flows and that constraints and/or risks may limit the ability the deliver environmental water.
20
Option 1 – Mid-Murrumbidgee wetland reconnection
Catchment: Murrumbidgee
Complex: Mid-Murrumbidgee River Wetlands
Site: Mid-Murrumbidgee Floodplain Wetlands
Applicable level(s) of resource availability: Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:




The purpose of this option is to provide hydrological connectivity to refill low-lying wetlands
in the Mid-Murrumbidgee Floodplain (Wagga to Hay). This is to continue the recent
improvements in wetland vegetation condition; provide habitat to maintain condition of
waterbirds, fish, other aquatic vertebrates (turtles, frogs) and macroinvertebrates; and allow
for movement and dispersal of aquatic animals.
Water would be delivered initially in winter 2013, with potentially a follow-up watering in late
spring 2013.
A large proportion of the flow is expected continue through to the lower Murrumbidgee
where it may provide beneficial inundation in the Junction Wetlands provided flows in the
Murray upstream of the junction are 10,000 ML/day or greater at the time.
A smaller portion of the flows from this option is likely to flow through to the Murray and
these may contribute to environmental flow requirements in the Lower Murray.
Timing
Winter 2013
Potentially also late spring 2013
Volume of
Commonwealth
environmental water
Up to 200 GL from all sources with nominally 150 GL of Commonwealth
environmental water and the remainder from other holdings.
Operational considerations and feasibility:





Flows would be delivered by State Water with the option managed by the NSW Office of
Environment and Heritage in consultation with a technical advisory group.
The requirement and timing for this flow will depend on whether a natural event inundates
the wetlands and will be considered in light of the results of the most recent vegetation, fish,
frog and water quality monitoring of the wetlands.
It is planned that the refilling of the Mid-Murrumbidgee Floodplain Wetlands would be
undertaken by piggy-backing onto a natural event. Should no suitable event occur by
mid/late August a stand-alone option would be considered.
The volume of environmental water required will depend on the volume of baseflows. The
preliminary target is for a flow of 28,000 ML/day (4.73 metres gauge height) or lower at
Gundagai to keep well under the bridge at Mundarlo, which is inundated when flows
exceed 29,500 ML/day (4.87 m gauge height, noting the flow rate has been reduced in line
with recent changes in the ratings tables for Gundagai and Wagga. Flows would be kept at
or below 30,000 ML/day (5.22 metres gauge height) at Wagga.
The environmental flow option would include a ramp up over 3 to 4 days and a recession
21




that mimics natural rates of recession (nominally a 10 per cent decrease in flow per day).
Should a rainfall induced unregulated event occur with flow sufficient to inundate MidMurrumbidgee wetlands, environmental water could be used to provide an extended
recession or to extend the period of inundation if required. However, any addition of
environmental water to the option would only be done when the flow has reduced below
28,000 ML/day at Gundagai. This would ensure environmental water does not extend the
duration of inundation of the bridge at Mundarlo. Decisions on whether and at what flow
rates to provide environmental water to a recession will be influenced by assessments of
any risks (including third party impacts) and the likely ecological benefits.
Environmental water would be delivered from Blowering and Burrinjuck dams with flow kept
at or below 8,500 ML/day (1.32 metres gauge height) at Tumut (that is to keep below the
Water Sharing Plan limit of 9,300 ML/day, which has been delivered through periods of
higher demand in the irrigation season, with an added buffer to provide extra assurance).
Where feasible, higher flows in the Murray may be coordinated with this option so that
beneficial inundation is also provided to the Junction Wetlands, downstream of the
Murrumbidgee.
If a flow was provided to reconnect wetlands in late spring this could provide some of the
required flows for, and provide additional benefits to, the proposed Murrumbidgee River
Fish Pulse targeting large and medium bodied fish (Option 3).
Risks to be considered and managed include:






Flows may enable breeding/recruitment of exotic species.
Watering in late spring may result in cold water pollution from dam releases with effects
particularly within approximately 200 km of the dams.
Environmental releases may be used to meet consumptive demand further downstream or
be re-regulated.
Environmental flows may impact riparian landholders by restricting access to land and/or
stock.
High irrigation extraction may reduce flows downstream so that commence to fill levels are
not reached for key wetlands. This risk is lower for an option undertaken in winter before the
irrigation season has fully underway. For an option in late spring the risk is much higher and is
likely that a watering option will only be possible if a period of low irrigation demand occurs
due to high rainfall. Even for a winter event it is possible that supplementary water take
during the event may reduce the peak of the flow below desired levels. Discussions with
major water extractors about the scheduling of their take (while ensuring required volumes
are still able to be accessed) may assist in reducing this risk.
Water extraction by consumptive users from some wetlands.
22
Option 2 – Mid-Murrumbidgee wetlands (infrastructure-assisted delivery)
Catchment: Murrumbidgee
Complex: Mid-Murrumbidgee River Wetlands
Site: Mid-Murrumbidgee Floodplain Wetlands
Applicable level(s) of resource availability: Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:
This option aims to refill wetlands in the Mid-Murrumbidgee Floodplain that have infrastructure
to allow delivery to them. The purpose of this option is to continue the recent improvements in
wetland vegetation condition and provide habitat to maintain condition of waterbirds, fish,
other aquatic vertebrates (turtles, frogs) and macroinvertebrates.
Timing
For initial filling: winter to early spring 2013.
For top up to provide water through summer: late spring to early summer
2013.
For top up to prevent desiccation of fish and frog communities and
juvenile turtles: mid-summer to early autumn 2014.
Initial filling for 2014 winter: late May to June 2014.
Volume of
Commonwealth
environmental water
Up to 10 GL from all sources with nominally 7 GL of Commonwealth
environmental water and the remainder from other holdings.
Operational considerations and feasibility:

The wetlands in the Mid-Murrumbidgee that can be delivered to via regulators and without
higher reconnecting flows include, but are not limited to:
o Gras Innes and Oaks Creek off Bundidgerry Creek
o Yanco Ag Lagoon, Turkey Flat and Gooragool Lagoon off Murrumbidgee Irrigation
infrastructure
o Coonancoocabil Lagoon (off Murrumbidgee Irrigation infrastructure or off Gogeldrie
Weirpool)
o A number of wetlands off the Yanco Creek system.

In some cases, access to channels will need to be negotiated with landholders or irrigation
corporations and agreement for inundation of privately owned wetlands will need to be
sought. Access to irrigation channels will only be possible after existing users needs have
been met first.

Delivery to Mid-Murrumbidgee wetlands through regulators is not as ecologically effective
as filling the wetlands with a reconnecting river flow. The higher river flow provides
hydrological connectivity for the exchange of biota, nutrients, sediment and carbon and
cues for biota. Infrastructure assisted delivery is only able to provide water to a very small
portion of the many hundreds of wetlands in the Mid-Murrumbidgee, the system as a whole
23
can only be maintained through reconnecting river flows.

If a reconnecting river flow (e.g. Option 1) is undertaken it will reach some of the low-lying
wetlands covered here. However, a number of the wetlands identified are higher and
environmental river flows cannot reach them under current constraints. These wetlands will
still require watering even if a reconnecting river flow is undertaken.

Metering is still required at some wetlands before licensed water may be used at those
locations.

Risks to be considered and managed include:
o Enabling breeding/recruitment of exotic species.
o Water extraction by consumptive users from wetlands
o Access to infrastructure may not be available at the required time
o For specific wetlands, water quality risks may need to addressed (e.g. for acid
sulphate soils, salinity and dissolved oxygen).
24
Option 3 – Murrumbidgee River Fish Fresh (targeting large and medium bodied
fish)
Catchment: Murrumbidgee
Complex: Murrumbidgee River Channel
Site: : Murrumbidgee River Channel
Applicable level(s) of resource availability: This option can be scaled for all levels of water
availability.
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:




This option aims to contribute to river flows (high-season base flows and freshes) to promote
movement and reproduction of large and medium bodied fish in the middle to lower
reaches of the Murrumbidgee River (Gogeldrie Weir to Balranald). The option would also
aim to promote reproduction, contribute to larval growth and survival and, dependant on
the peak flow, reconnect low-lying wetlands and allow fish movement into, and out of,
these wetlands.
Water would be delivered, in stages, over a period of 6 to 10 weeks during spring–early
summer 2013. The flow regime could include:
- ramping up flows (if required) to 6,000–8,000 ML/day over 4–5 days
- maintaining a baseline flow between 6,000–8,000 ML/day for up to 40 days to
inundate trout cod and Murray cod nesting sites
- providing a peak flow of up to 16,000 ML/day (where achievable) for 4–5 days to
promote larval dispersal
- providing a gradual recession from the peak flow to baseline flows over 15 days or
more
Note: all flow rates measured at Darlington Point.
The key reasons for selecting this flow regime provided by DPI NSW (Fisheries) (Luke Pearce,
unpublished 2012) were:
- Murray cod and trout cod predictably spawn over a restricted window
(approximately 6 weeks)
- Flows are known to stimulate movement in all four target species (Murray cod, trout
cod, silver perch and golden perch)
- Golden perch and silver perch are known to spawn on river rises and have semibuoyant eggs that would passively disperse downstream during the option
- Murray cod and trout cod have demersal eggs with parental care for up to 8 days
(so inundating nest sites for a prolonged period is required to ensure spawning and
hatching)
- These eggs hatch and larvae remain in nest post hatching for 5–7 days prior to
drifting
- Flows can assist with dispersal for all species
The target reach is from below Darlington Point to Hay. This reach was chosen because it is
downstream of major irrigation off-takes. However, flows are likely to provide benefits for fish
in other reaches.
25

A portion of the flows are likely to flow through to the Murray and may contribute to
environmental flow requirements in the Lower Murray.
Timing
Spring 2013 – starting September–October and ending December.
Flows will commence to coincide with either an increase in water
temperature to around 16–17 degrees or a day length known to trigger
fish spawning (~early October). Evidence of preparedness to spawn
from observations at the Narrandera Fisheries Centre will also be used
where available to help determine the optimal start date for the option.
Volume of
Commonwealth
environmental water
This option would require approximately 225 GL from all sources (based
on the volume required from this action in 2012). Of this nominally 150 GL
would be Commonwealth environmental water and the remainder from
other environmental holdings.
Operational considerations and feasibility:






Environmental water would be delivered from Blowering and Burrinjuck dams. Tombullen
Storage and weirs on the river channel may also be used to prevent flows from rising or
falling too quickly (flows can go up and down due to rainfall events, rainfall rejections of
orders or higher than expected take from the channel).
The use of weir pools is limited by requirements to keep within acceptable rates of rise and
fall at these structures.
Flows will be maintained in-channel.
Flows will be adaptively managed to integrate with other demands in the system and
higher natural flow events.
A similar action was successfully delivered from October to December 2012. Results from
monitoring from that action will be used to help target the timing of the watering option in
2013.
This option could provide an additional Mid-Murrumbidgee Wetlands reconnection if
provided in the spring after the winter reconnection outlined in Option 1. The ability to
provide the reconnection of low-lying wetlands as part of this option in late spring will
depend on water availability, channel capacity and potential impacts on riparian
landholders.
Risks to be considered and managed include:




Watering in late spring may result in cold water pollution from dam releases with effects
particularly within approximately 200 km of the dams.
Environmental releases may be used to meet consumptive demand further downstream or
be re-regulated.
Environmental flows may impact riparian landholders by restricting access to land and/or
stock (if a wetland reconnection was to be undertaken as part of this option).
Higher than forecast irrigation extraction may reduce flows downstream so that wetland
reconnection may not be possible as part of this option.
26
Option 4 – Murrumbidgee River Fish Fresh (targeting small bodied fish)
Catchment: Murrumbidgee
Complex: Murrumbidgee River Channel
Site: : Murrumbidgee River Channel
Applicable level(s) of resource availability: Moderate-high
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:



Contribute to river flows (elevated baseflow and repeated small freshes) to promote
movement, spawning and contribute to larval growth and survival of small-bodied fish in
the middle to lower reaches of the Murrumbidgee River (between Gogeldrie Weir and
Balranald).
Water would be delivered, in freshes, over a single period of up to 50 days between
September 2013 and April 2014. Water use under this option could target a series of peak
flows (up to three) of approximately 4,000 ML/day (~34% of bankfull height) at Darlington
Point for 5–10 days each, to inundate reproduction habitat (logs, vegetation), promote fish
movement and stimulate reproduction. Flows between peaks would be maintained above
2,500 ML/day to ensure eggs remain inundated. Flows after the last peak would be
reduced slowly to ensure any larvae do not become stranded.
Flow requirements are based on advice from NSW Department of Primary Industries
(Fisheries).
Timing
Volume of
Commonwealth
environmental water
Spring to autumn 2013–14
Up to 40 GL of environmental water from all sources, depending upon
antecedent conditions and the timing of the release. Of this nominally
up to 30 GL would be Commonwealth environmental water and the
remainder from other environmental holdings
Depending on water availability, the level of peak flows may be
reduced and the number of peaks (and correspondingly, the duration
of the option) may be reduced to reduce the volume of water required.
Operational considerations and feasibility:





Environmental water would be delivered from Blowering and Burrinjuck dams. Tombullen
Storage and weirs on the river channel may also be used to prevent flows from rising or
falling too quickly (flows can go up and down due to rainfall events, rainfall rejections of
orders or higher than expected take from the channel).
The use of weir pools is limited by requirements to keep within acceptable rates of rise and
fall at these structures.
Flows are well below channel capacity (maximum 35% of bankfull height).
Flows will be adaptively managed to integrate with other demands in the system and
higher natural flow events.
The level of peak flow and elevated base flow targeted will have consideration of the likely
levels of baseflow under natural conditions for each season. Therefore the level of peak
27





and elevated baseflow targeted would be lower if the option takes place in autumn than if
it occurs in spring.
The option will be planned to be triggered by a natural or unregulated rise in flows. This, in
combination with possible rainfall rejections and underlying water in the river for other
deliveries during the option may mean that environmental water is only required to ‘fill the
holes’ where flows would otherwise dip below the desired hydrograph and thereby
significantly reduce the amount of environmental water required for the option.
Depending on water availability, antecedent conditions and advice from stakeholders, this
option may be delivered as multiple discrete peaks rather than a single option. If so, Option
5 (restoring natural flow variability) would be delivered with an appropriate timing to
provide outcomes for small-bodied fish.
Note that should the large-bodied fish pulse (Option 3) take place in spring that is expected
to meet the objectives of this option for spring.
Using the new Beavers Creek Weir to provide the desired hydrograph in the Old Man Creek
system independent of flows in the Murrumbidgee main channel would also be considered
once these works are complete.
Risks to be considered and managed include that environmental releases may be used to
meet consumptive demand further downstream or be re-regulated.
28
Option 5 – Restoring natural flow variability
Catchment: Murrumbidgee
Complex: Murrumbidgee River Channel
Site: : Murrumbidgee River Channel
Applicable level(s) of resource availability: All levels of water availability
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:



Contribute to river flows delivered to the Murrumbidgee River channel, Yanco-ColomboBillabong Creek system and/or Old Man Creek system to restore natural events that are
truncated by river regulation and/or extraction. Water would be delivered year round to
restore flows such as: a) small to moderate freshes (natural freshes following rainfall events);
b) high-flow season base flows (winter-spring); and c) the natural recession of larger events.
Expected outcomes include maintaining natural condition of fish and macroinvertebrates
(by maintaining cues for fish and other biota, scouring of bio-films, improved entrainment
and movement of leaf litter into and along the channel, and improved zooplankton
productivity).
Target events will be selected taking into account factors including period since last similar
event, seasonality, species likely to benefit, potential risks (including cold water pollution
from dam releases), secondary benefits (particularly where water provided in the
Murrumbidgee could contribute to flow requirements in downstream systems) and volume
of water required.
Timing
Full year, though likely to only be in scope in period December 2013 to
June 2014
Should the Murrumbidgee River Channel Fish Fresh (Option 3) be
undertaken as proposed in September–December 2013, there would be
no requirement for additional channel flows during this period.
Thereafter, environmental water use would be triggered by natural
events.
Volume of
Commonwealth
environmental water
The water made available is scalable dependent on water availability
and requirements. It is anticipated somewhere between 50 to 100 GL of
water could be provided from all sources. Of this, nominally 35 to 70 GL
would be Commonwealth environmental water and the remainder from
other environmental holdings.
Operational considerations and feasibility:

Environmental releases would be kept in channel and are not intended to inundate
floodplain or wetland habitat. Natural flows may be altered by capture in headwater
storages (in which case a release from storages may be called for) or reduced by
extraction (in which case Tombullen storage or in channel weirs may be used to help
replace some of the flow). For an event that occurs below the headwater storages and
29




which would otherwise be captured in weirpools and Tombullen water storage, the event
could be allowed to pass through naturally with environmental water allocations used to
‘pay’ for the foregone storage.
The use of weir pools is limited by requirements to keep within acceptable rates of rise and
fall at these structures.
In the case of freshes, the timing and scale of release would be triggered by a natural
event in the Goodradigbee River. Environmental flows will be scaled based on inflows from
major tributaries to ensure flows do not exceed target thresholds.
Flows through Old Man Creek would only be considered once the works on the weir at the
top of the system are complete and further considerations of the flow requirements of the
system have been undertaken.
Risks to be considered and managed include that environmental releases may be used to
meet consumptive demand further downstream or be re-regulated.
30
Option 6 – Lowbidgee – wetlands in Yanga, North Redbank, Nimmie-Caira and
Fiddlers-Uara Creek system
Catchment: Murrumbidgee
Complex: Lowbidgee
Site: Yanga, Nimmie-Caira, North Redbank and Fiddlers-Uara Creek system
Applicable level(s) of resource availability: All levels of resource availability
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:


Using regulators, inundate wetlands in the North Redbank system, South Redbank (Yanga),
Nimmie-Caira and Fiddlers-Uara Creek systems to maintain and improve wetland
vegetation diversity and condition (lignum, black box and river red gums and associated
understory communities such as reeds, sedges and rushes), and provide habitat to support
survival and maintain condition of fish, waterbirds and other aquatic vertebrates (frogs).
In the North Redbank system consideration will be given to using escapes that allow water
to return to the channel to improve hydrological connectivity and provide for transport of
biota, nutrients, sediment and carbon.
Timing
Volume of
Commonwealth
environmental water
Winter/spring
Up to 180 GL from all sources, with nominally 120 GL of Commonwealth
environmental water with the remainder from other environmental
holdings.
Operational considerations and feasibility:

Wetlands in the North Redbank system would be watered off the North Redbank Channel.
Where practical, Baupie Escape may be able to be used to allow flows to return to the
river.

Wetlands in Yanga National Park would be watered through the Yanga (1AS) and
Waugorah (1ES) regulators and, where channel access is available, through the NimmeCaira system.

Wetlands in the Nimmie-Caira system and Fiddlers-Uara Creek system could be watered
through the Nimmie-Caira channel systems, which distribute water from Maude Weirpool.

Channel access in North Redbank and through the Nimmie-Caira system is dependent on
agreement with landholders. Where wetlands are on private land, agreement with private
landholders to inundate wetlands will be required.

The requirement for water will be regularly assessed. The Lowbidgee has had good
watering over the previous two years. The requirement for water will depend on the degree
of drying over autumn–winter 2013, the vegetation types supported in each wetland (e.g.
whether it is black box, which requires watering less frequently, or an area dominated by
sedge/rush wetland, which requires more frequent watering) and the condition of the
vegetation (e.g. if it is still recovering from decline during the drought and needs follow-up
31
watering to continue recovery).

Delivery in Yanga will need to consider how the southern and middle areas of the park may
best be watered without overwatering the northern areas through which water passes onroute.

This option may be able to be undertaken in conjunction with other upstream options. For
example, flows from the Mid-Murrumbidgee wetlands reconnection flow (Option 1) could
provide water for this option as well. There are also potential ecosystem benefits at a
landscape scale from linking the timing of the inundation of upstream and downstream
wetlands. However, channel usage by existing users in the Lowbidgee may reduce the
capacity to do this.

Risks to be considered and managed include supporting breeding and recruitment of
exotic species and not being able to undertake environmental watering due to lack of
channel access.
32
Option 7 – Wetlands west of the North Redbank Channel
Catchment: Murrumbidgee
Complex: Lower Murrumbidgee Floodplain
Site: Wetlands and Lakes at the western edge of the Lowbidgee Floodplain
Applicable level(s) of resource availability: All levels of resource availability, but dependant on
assessment of condition and water requirements of targeted sites
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:





Inundation of wetlands and lakes located at the western edge of the Lowbidgee
Floodplain (northwest of Balranald and west of the North Redbank Channel) to promote
continued recovery of riparian and wetland vegetation communities, and to provide
habitat to support condition of native waterbirds, fish and other aquatic vertebrate (turtles,
frogs). Inundation of these lakes and wetlands would have the added benefit of
replenishing groundwater reserves, thus improving ecosystem resilience ahead of possibly
drier conditions in the near future.
Delivery would occur over approximately 90 days until target lakes and wetlands are filled.
Target sites include Hobblers Lake, Cherax Swamp, Penarie Creek and the Narwie West,
Black Box and Reed Bed wetlands. These sites, some of which had been isolated from the
Lowbidgee floodplain since 1912, received Commonwealth and NSW environmental water
(several for the first time) from October to December 2012. Cherax Swamp and the Narwie
West, Reed Bed and Black Box wetlands had previously received NSW environmental water
from May 2011 to January 2012.
For the ‘western lakes’ (i.e. the wetlands west of the Ivanhoe Road: Hobblers Lake, Cherax
Swamp, Penarie Creek and Black Box and Red Bed wetlands), expected outcomes focus
on recovery of riparian vegetation and provision of habitat for waterbirds; while for the river
red gum wetlands between the Ivanhoe Road and the North Redbank channel (Narwie
West and connecting waterways), environmental watering would promote recovery of
wetland vegetation condition and provide habitat for other aquatic vertebrates (e.g. frogs)
in addition to waterbirds.
The NSW Office of Environment and Heritage reported positive ecological responses to the
2011–12 watering including fresh growth on black box trees fringing the lakes and wetlands,
establishment of new black box seedlings, 35 species of waterbirds, including three
threatened species. Preliminary results of monitoring of ecological responses to the
watering in Spring 2012 (conducted by Charles Sturt University) indicate continued
improvements in tree health, a strong aquatic vegetation response at Narwie West wetland
and large numbers of waterbirds across all sites. Watering in 2013–14 aims to consolidate on
the ecological gains made in 2011–12 and 2012–13.
Timing
Volume of
Commonwealth
environmental water
Spring 2013
Up to 9 GL from all sources, with nominally 6 GL of Commonwealth
environmental water with the rest from other environmental holdings.
33
Operational considerations and feasibility:

Environmental water would be delivered from North Redbank Channel, through the Narwie
West regulator into Narwie West wetlands, along Yarrawol Creek, then Paika Creek and
through new works under the Ivanhoe Road to Cherax Swamp, Hobblers Lake, Penarie
Creek and Black Box and Reed Bed wetlands.

Flow will be accounted for by State Water from North Redbank Channel, using flow data
from the Athen gauging station located on North Redbank Channel approximately 2 km
upstream of the Narwie West regulator.

Delivery rates through the Narwie West regulator are limited to a maximum of 500 ML/day
and will be adjusted down as required during the option in response to local conditions in
the target lakes, wetlands and connecting waterways as well as to keep within the desired
level of spread on the Narwie West wetland.

Feasibility of delivery will depend on, among other factors, availability of channel capacity
in North Redbank Channel during spring 2013.

The historical inundation frequency of the Western Lakes (prior to isolation) is currently being
investigated by Charles Sturt University, the NSW Office of Environment and Heritage and
the Commonwealth Environmental Water Office. Long-term watering planning for the
western lakes and wetlands will incorporate these results as they become available.
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Option 8 – Contingency to support significant bird or other aquatic native
vertebrate breeding event in wetlands
Catchment: Murrumbidgee
Complex: Lower Murrumbidgee Floodplain, Mid-Murrumbidgee River Wetlands and Other
Murrumbidgee Catchment Sites
Site: North Redbank wetlands, Yanga National Park, Nimmie-Caira system, regulated MidMurrumbidgee Wetlands and Wanganella Swamp (on Forest Creek in Yanco-BillabongColombo Creek System)
Applicable level(s) of resource availability: All levels of resource availability
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:



Maintain wetland water levels and acceptable levels of water quality to support the
completion of a significant reproduction event of waterbirds or other native aquatic
vertebrates in a wetland.
This contingency is not to trigger a reproduction event but for use when a reproduction
event is already underway and considered in danger of failure due to receding water
levels.
The option is to support waterbirds, including colonial nesting birds, and other aquatic
native vertebrates such as frogs (particularly the southern bell frog) and turtles.
Timing
Volume of
Commonwealth
environmental water
Late spring 2013 to early autumn 2014
Water required will depend on the size of the site, location of the site
(and therefore how much transition losses may be expected) and the
duration the event needs to be supported for.
Up to 20 GL of environmental water from all sources may be required,
with nominally up to 15 GL of Commonwealth environmental water with
the remainder provided from other environmental holdings.
Operational considerations and feasibility:



Environmental water would be delivered through North Redbank Channel for wetlands in
the North Redbank system, through the 1AS (Yanga) and 1ES (Wagorah) regulators for
wetlands in Yanga National Park. For the Nimmie-Caira system the channel system could be
utilised however access to these channels would have to be negotiated with the
landholders.
A small number of Mid Murrumbidgee Wetlands may be watered using channels and
regulators, including through the Murrumbidgee Irrigation system, off Yanco Creek, off
Bundidgerry Creek and off Gogelderie Weir. In some cases channel use will have to be
negotiated with the relevant infrastructure/land owner.
For Wanganella Swamp on Forest Creek in the Yanco-Colombo-Billabong system a weir on
Billabong Creek can divert a portion of flows down Forest Creek. Due to large attenuation
along Yanco Creek delivery through Finlay Escape from the Murray River using Murray
Irrigation Limited infrastructure would be more efficient and will be considered should a
35


reproduction event occur.
If the reproduction event occurs some distance from channels or regulators significant
volumes of water may be used in transit to the target wetland.
Risks to be considered and managed include that falling water levels may trigger birds to
abandon nesting sites before top-up flows can be delivered, with water delivery times to
these wetlands often lengthy.
36
Option 9 – Murrumbidgee River Fish Refuge (contingency for adverse water
quality issues)
Catchment: Murrumbidgee
Complex: Murrumbidgee Catchment river flows
Site: Murrumbidgee River Channel
Applicable level(s) of resource availability: Very high to high (for water quality impacts caused
by natural flooding); very low (for impacts caused by drying down).
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

River flows targeting the lower reaches of the Murrumbidgee River channel to provide
localised refuge habitat for fish and aquatic biota. The trigger for this option would be
either a natural flooding event or drying down that creates an adverse water quality issue
in the lower catchment. Depending on the nature of the event, this option could target
flows of 4,500 ML/day downstream of Maude Weir for approximately one month (noting
that 4,500 ML/day at Maude Weir represents approximately half channel capacity).
Timing
Volume of
Commonwealth
environmental water
The timing is dependent on the occurrence of an adverse water quality
event, and the capacity to deliver environmental flows. Most likely to
occur from December onwards, as water temperatures increase.
Up to 80 GL from all sources with nominally 60 GL of Commonwealth
environmental water and the remainder from other environmental
holdings.
.
Operational considerations and feasibility:




Environmental water will be delivered from Blowering and Burrinjuck dams as well as
Tombullen Storage and River Channel weirs.
Delivery constraints such as high flow, the scale of the water quality issue and channel
capacity may play a significant role in the feasibility of this option.
Environmental releases should remain in-channel and not promote floodplain inundation.
The critical threshold is the channel capacity in the Lowbidgee is between 8,000 and
10,000 ML/day. Flows will be maintained below this level.
The use of weir pools is limited by requirements to keep within acceptable rates of rise and
fall at these structures.
37
Option 10 – Silver Pines anabranches and wetlands
Catchment: Murrumbidgee
Complex: Yanco, Billabong Creek system
Site: Silver Pines anabranches and wetlands
Applicable level(s) of resource availability: Low–High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The option would aim to maintain wetland vegetation condition (including river red gums)
by reconnecting and refilling the anabranch creeks and lagoons on the property ‘Silver
Pines’.
Timing
Volume of
Commonwealth
environmental water
Winter–spring 2013
Up to 2.5 GL from all sources with nominally 1.7 GL of Commonwealth
environmental water and the remainder from other environmental
holdings.
Operational considerations and feasibility:


Delivery would require a moderate unregulated flow event in Yanco Creek below Tarabah
Weir. Environmental water delivery would be provided through Coleambally Catchment
Drain (CCD) to ‘piggy back’ onto this to help reconnect and refill the low-lying
anabranches and wetlands of Silver Pines. The CCD joins Yanco Creek just upstream of
Silver Pines. Delivering via the CCD would avoid any unwanted inundation upstream of the
CCD escape.
The current capacity of the CCD is 150 ML/day. An upgrade is planned to bring this up to
350 ML/day but this may not be in time to help with an option in winter–spring 2013.
Risks to be considered and managed include:
 Flows may enable breeding or recruitment of exotic species.
 Environmental releases may be used to meet consumptive demand further downstream or
be re-regulated.
 Environmental flows may impact riparian landholders by restricting access to land and/or
stock.
 Managed reconnection of the Silver pines wetlands has not been done before so it is
possible that deliveries may ‘undershoot’ the commence-to-fill levels of the wetlands in the
initial stages of the option.
38
6.2.
Assessment of environmental watering options
The proposed watering options will be assessed closer to the proposed timing for delivery using
the criteria for assessing environmental watering actions. This assessment will form part of the
Commonwealth Environmental Water Office’s assessment of seasonal, operational and
management considerations and will inform a recommendation to the Commonwealth
Environmental Water Holder to approve water use. A description of these criteria is provided in
the Framework for Determining Commonwealth Environmental Water Use which is available at:
www.environment.gov.au/water/publications/action/pubs/cehw-framework.pdf.
This assessment will include a comprehensive risk assessment which is subject to the prevailing
valley and river flow conditions, and will consider proposed costs, delivery, monitoring and
accounting arrangements, and potential third party impacts. Any additional watering options
identified during the course of the year will also be subject to an assessment against the
criteria.
39
7. Accounting for the use of Commonwealth
environmental water
7.1.
Water use accounting
Across New South Wales, Commonwealth environmental water is generally transferred to the
New South Wales Office of Environment and Heritage’s environmental accounts. The NSW
Office of Environment and Heritage is then responsible for making arrangements to deliver the
environmental water with river operators such as the State Water Corporation.
River flows will be accounted for at storages or at downstream flow gauges and will be
reported to the Commonwealth Environmental Water Office by the NSW Office of Environment
and Heritage. Where applicable, water delivered to individual wetland sites will be accounted
at flow gauges or metered pumps at those sites.
7.2.
Operational monitoring
Operational monitoring is monitoring that helps assess whether water has been delivered as
planned (e.g. the volumes, timing (frequency and duration), location and flow rates of water
delivered) and can include observations of immediate environmental responses.
This monitoring is mostly undertaken by delivery partners in conjunction with the Office. In the
Murrumbidgee River Valley, this includes NSW State Water and the NSW Office of Environment
and Heritage.
Delivery partners provide regular operational monitoring updates to the Commonwealth
Environmental Water Office. The operational monitoring requirements are set out in the
Commonwealth Environmental Water Office Operational Monitoring template.
Key parameters required through operational monitoring are:

Date of Commonwealth environmental water delivery (commencement and finish).

Point of debit/delivery (both if they are different).

Volume of Commonwealth environmental water delivered (provided on a weekly basis).

Flow rate that water is delivered at (hydrograph of delivery if possible).

Monitoring associated with identified risks.
40
8. Partnerships
The Office has consulted with a range of stakeholders to develop the Commonwealth
environmental water use options for the Murrumbidgee River Valley for 2013–14. These include:

Environmental Water Scientific Advisory Panel

Murray-Darling Basin Authority

New South Wales Office of Environment and Heritage

New South Wales Office of Water

New South Wales Department of Primary Industries (Fisheries)

Murrumbidgee Environmental Water Allowance Reference Group

Murrumbidgee Catchment Management Authority

Murrumbidgee Customer Services Committee.
The Office will continue to work with stakeholders and other interested community members in
the planning, delivery, management and monitoring of Commonwealth environmental water.
41
9. Bibliography
Cameron, L. and Baumgartner, L.J. (2013). Management Plan to Use Environmental Water to
Enhance the Murrumbidgee River System for Native Fish. Report to NSW Office of Environment
and Heritage, Grafton, NSW. CSIRO (2008). Water Availability in the Murrumbidgee. A Report
to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project.
CSIRO, Australia 155pp.
Davies, P.E., Stewardson, M., Hillman, T., Roberts, J., and Thoms, M. (2008). Sustainable Rivers
Audit 2: The ecological health of rivers in the Murray-Darling Basin at the end of the Millenium
Drought (2008-2010). Prepared by the Independent Sustainable Rivers Audit Group for the
Murray–Darling Basin Ministerial Council.
Murray, P.A. (2008) Murrumbidgee Wetlands Resource Book. Murrumbidgee Catchment
Management Authority, 111 pp.
NSW Office of Environment and Heritage (2012). Murrumbidgee River Valley Draft Annual
Environmental Watering Plan 2012–13. NSW Office of Environment and Heritage, Sydney.
Page, K., Read, A., Frazier, P., Mount, N. (2005). The effect of altered flow regime on the
frequency and duration of bankfull discharge: Murrumbidgee River, Australia. River Research
and Applications, Vol. 21, pp. 1-12.
Sinclair Knight Merz (SKM) (2011). Environmental Water delivery: Murrumbidgee River Valley.
Prepared for Commonwealth Environmental Water.
Wassens, S., Watts, R.J., Spencer, J.A., Howitt, J., McCasker, N.A., Griese, V., Burns, A., Croft, R.,
Zander, A., Amos, C. and Hall, A. (2012). Monitoring of ecosystem responses to the delivery of
environmental water in the Murrumbidgee system. Institute for Land, Water and Society,
Charles Sturt University, Report 2.
42