Commonwealth environmental water
use options 2014–15:
Namoi River Valley
1
Cover image credit: Namoi River, Gunnedah. Photo: Andrew Warden © 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.
© Copyright Commonwealth of Australia, 2014.
Commonwealth environmental water use options 2014–15: Namoi River Valley is licensed by the Commonwealth of
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This report should be attributed as ‘Commonwealth environmental water use options 2014–15: Namoi River Valley,
Commonwealth of Australia 2014’.
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 the Environment. 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.
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Commonwealth environmental water use options
2014–15: Namoi River Valley
Table of contents
1. Background ........................................................................................................ 5
1.1.
Demonstrating how Commonwealth environmental water in 2014–15 will
contribute to the Basin Plan’s environmental watering plan objectives – Namoi
River Valley .................................................................................................................................. 5
2. Context for water use in 2014–15 in the Namoi River Valley ......................... 8
2.1.
Delivering environmental water to the Namoi River Valley .............................................. 8
2.2.
Operational and management considerations for 2014–15 in the Namoi River
Valley ........................................................................................................................................... 9
2.3.
Valley condition ....................................................................................................................... 10
3. Water availability ............................................................................................. 12
3.1.
Commonwealth environmental water holdings in the Namoi River Valley for 2014–
15................................................................................................................................................. 12
3.2.
Other sources of environmental water allocations .......................................................... 12
3.3.
Natural or unregulated flows and planned environmental water ................................ 12
4. Planning for water use in the Namoi River Valley in 2014–15 ...................... 14
4.1.
Planning for a range of inflows in 2014–15 .......................................................................... 14
4.2.
Implementing watering actions throughout the year ...................................................... 15
5. Water use options for 2014–15 ........................................................................ 16
5.1.
Summary of watering options ............................................................................................... 16
5.2.
Assessment of environmental watering options ................................................................ 18
5.3.
Options contributing to the Basin Annual Environmental Watering Priorities .............. 24
6. Accounting for the use of Commonwealth environmental water .............. 25
6.1.
Water use accounting ............................................................................................................ 25
6.2.
Monitoring ................................................................................................................................. 25
6.2.1.
Operational monitoring ................................................................................................. 25
6.2.2.
Long term intervention monitoring .............................................................................. 25
7. Next steps – from planning to water delivery ............................................... 27
8. Partnerships ...................................................................................................... 29
9. Bibliography ..................................................................................................... 30
3
List of Figures
Figure 1: The Namoi River Valley (Green et al. 2011). ............................................................................. 9
Figure 2: How inflows may vary and impact on water resource availability over the course of
2014–15 in the Namoi River Valley, from a starting point of low to high resource availability. ..... 14
Figure 3: The annual management process for Commonwealth environmental water. .............. 28
List of Tables
Table 1: Expected outcomes from the use of Commonwealth environmental water in the
Namoi River Valley. ........................................................................................................................................ 6
Table 2: Operational considerations for the Namoi River Valley in 2014–15. ................................... 10
Table 3: Commonwealth environmental water holdings in the Namoi River as at 30 April
2014. ................................................................................................................................................................ 12
Table 4: Summary of potential water use options for the Namoi River Valley in 2014-15. ............. 17
Table 5: 2014–15 Basin annual environmental watering priorities for the Namoi River Valley ...... 24
4
1. Background
This document is designed to be read in conjunction with the Commonwealth environmental
water use options 2014–15: 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 Namoi River Valley this water 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.
1.1.
Demonstrating how Commonwealth environmental water in 2014–15 will
contribute to the Basin Plan’s environmental watering plan objectives –
Namoi River Valley
Commonwealth environmental water use options for the Namoi River Valley in 2014–15 include
the following three flow types:

base flows (low flows)

freshes

bankfull.
These flow types are illustrated in Figure 4 of the document Commonwealth environmental
water use options 2014–15: Planning approach.
Commonwealth environmental water delivery within the Namoi River Valley may be delivered
to various parts of the river system including:

anabranches

small flood runners

and in-stream pool habitats.
The ecological response from delivering Commonwealth environmental water is reflected in
the expected outcomes.
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. For further information please refer to The Environmental Water
Outcomes Framework at www.environment.gov.au/water/cewo/publications/environmentalwater-outcomes-framework.
5
Table 1 shows the linkage between planned flow types and the expected outcomes for the
Namoi River Valley. The table also links the short-term expected outcomes to a long-term
contribution to the four Basin Plan objectives at the Basin scale (i.e. biodiversity, ecosystem
function, resilience and water quality).
Table 1: Expected outcomes from the use of Commonwealth environmental water in the
Namoi River Valley.
Flow Type
Expected outcomes for
2014–15
Contributions to
longer term
objectives
Contribution to the
following Basin Plan
objective
Base flows (low flows)
Hydrological connectivity,
including end of system
flows
Connectivity
Ecosystem Function
Individual survival and
condition (individual
refuges)
Population condition
(individual refuges)
Resilience
Individual condition
(ecosystem resistance)
Population condition
(ecosystem recovery)
Resilience
Management of water
quality issues (salinity,
dissolved oxygen, pH and
dissolved organic carbon)
Chemical
Water Quality
Vegetation condition and
reproduction
Vegetation diversity
Biodiversity
Vegetation germination
and dispersal
Vegetation growth and
survival
Biodiversity
Within ecosystem
macroinvertebrate
diversity
Macroinvertebrate
diversity
Biodiversity
Fish condition
Fish diversity
Biodiversity
Fish reproduction, larval
growth and survival
Larval and juvenile
abundance
Biodiversity
Waterbird survival and
condition
Waterbird diversity and
population condition
Biodiversity
Other vertebrate
reproduction, growth and
survival
Adult abundance
Biodiversity
Hydrological connectivity,
including end of system
flows
Connectivity
Ecosystem Function
Mobilisation and dispersal
of biotic and abiotic
materials
Connectivity
Ecosystem Function
Primary production,
decomposition, nutrient
and carbon cycling
Process
Ecosystem Function
Individual condition
(ecosystem resistance)
Population condition
(ecosystem recovery)
Resilience
Management of water
quality issues (salinity,
Chemical
Water Quality
Freshes and bankfull
6
Flow Type
Expected outcomes for
2014–15
Contributions to
longer term
objectives
dissolved oxygen, pH and
dissolved organic carbon)
7
Contribution to the
following Basin Plan
objective
2. Context for water use in 2014–15 in the
Namoi River Valley
2.1.
Delivering environmental water to the Namoi River Valley
The Namoi River Valley is located in north eastern New South Wales (NSW), extending
westwards of Nundle to Walgett. Rainfall in the upper catchment drives valley flows, with water
for regulated delivery throughout the valley being stored in Split Rock and Keepit dams. There
are also a number of smaller regulating weirs downstream of Keepit Dam. At 845 km in length,
the Namoi River is the primary riverine asset and constitutes a major tributary of the Barwon
River. Major tributaries into the Namoi include Cox’s Creek and the Mooki, Manilla and the Peel
rivers, which join the Namoi River upstream of Boggabri. Flows are confined in-channel until the
floodplain begins to broaden at Gunnedah. The Pian (an anabranch of the Namoi River),
Narrabri, Baradine and Bohena creeks contribute flows downstream of Boggabri.
The Peel River contributes an average annual volume of approximately 280 000 megalitres (ML)
into the Namoi system (Green et al. 2011) and as such constitutes the other key asset within the
Namoi River Valley. Flows are regulated out of Chaffey Dam and flow into the Namoi River
slightly downstream of Keepit Dam. Major tributaries into the Peel River are Goonoo Goonoo
Creek, Cockburn River and Dungowan Creek.
To date, opportunities to deliver environmental water into the Namoi River have been limited
to baseflow and lower Namoi in-channel fresh requirements. Commonwealth environmental
water is now held in the Peel. Should an action be triggered, anticipated outcomes include
improved habitat condition for instream vegetation, fish, frogs and turtles.
Baseflows are in-channel flows, which can be satisfied through relatively low release rates from
the relevant storage. Baseflows target nutrient cycling, fish passage and riparian health
outcomes. In-channel fresh events aim to improve nutrient cycling, facilitate the migration and
recruitment of native fish species and enhance anabranch connection and riverine
woodlands. Environmental water is most likely to be undertaken in conjunction with a naturally
occurring fresh flow trigger, or prolonged low flow conditions. In the Namoi River the 2013–14
water year experienced below average rainfall and above average temperatures. Whilst
some rain was recorded, flows were generally unsuitable to trigger delivery of Commonwealth
environmental water.
In order to achieve lower Namoi in-channel fresh requirements regulated releases from Keepit
Dam can be timed to coincide with unregulated inflows from the Mooki River and Cox’s Creek.
Benefits may also extend downstream to the Barwon-Darling. Consideration may also be given
to augmenting modified river management practices that may be implemented by river
operators in response to low inflows, such as block releases of consumptive water orders.
Where possible, environmental water will be managed for the benefit multiple sites to maximise
the efficiency and effectiveness of water delivery.
Held environmental water into the Peel River can be made available from Chaffey Dam in
combination with downstream unregulated tributary inflows, or as a form of translucency
release in response to storage inflows. Use of Commonwealth environmental water is not
contingent on unregulated flows in the Peel River and can be delivered in conjunction with a
stimulus flow managed by the NSW Office of Water under the existing environmental water
plan.
8
Figure 1: The Namoi River Valley (Green et al. 2011).
2.2.
Operational and management considerations for 2014–15 in the Namoi
River Valley
In the Namoi, the achievement of desired environmental outcomes for fresh flows will be
closely related to the careful coordination of the timing of Commonwealth environmental
water releases to coincide with existing unregulated flows in the Namoi River. When a low
inflow scenario predominates, Commonwealth environmental water could be used in
conjunction with minimum releases to provide low flow variability and protect water quality
and drought refuge values.
In order to achieve desired environmental outcomes in the Peel River under a fresh flow
scenario, Commonwealth environmental water delivery could be coordinated with the NSW
stimulus flow. Alternatively, unregulated flows that originate from tributary inflows could be
used to piggy-back releases from Chaffey Dam. To achieve environmental outcomes in the
Peel under low inflow scenarios, Commonwealth environmental water could provide low flow
variability for low base flows provided out of Chaffey Dam under the water sharing plan.
The lower Namoi entitlement has a maximum use in a single year of 125 per cent of entitlement
(subject to the account balance) and 300 per cent of entitlement over three consecutive
years. The Peel allocation cannot be carried over and unused water is forfeited.
Operational considerations such as delivery methods, opportunities, constraints and risks will
differ depending on the inflow scenario and are summarised in Table 2. These considerations
will be assessed throughout the year as decisions to make water available for use are made
and implemented. This includes refining the ecological objectives, assessing operational
feasibility and potential risks and the ongoing monitoring of the seasonal outlook and river
conditions.
9
Table 2: Operational considerations for the Namoi River Valley in 2014–15.
Inflow scenario
Very low
Low
Moderate
High
Very high
Opportunities
Manage the recession of unregulated
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
and/or stimulus flow releases
Augment regulated flows to improve
environmental outcomes.
End of system flows contribute to
additional environmental outcomes in the
Barwon-Darling system.
Constraints
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.
Maximum annual usage on entitlements is
up to 125 per cent of entitlement.
Flow thresholds for existing river
infrastructure may constrain the delivery of
environmental water.
Risks*
The provision of Commonwealth
environmental water must consider
potential inundation impacts to property
and infrastructure.
*See Section 7 for more information on risk management.
2.3.
Valley condition
The MDBA’s 2012 Sustainable Rivers Audit report rated the river ecosystem health of the Namoi
River Valley as poor. This was after eight consecutive years of below average flow from 2001 to
2009, combined with the existing effects of river regulation. While hydrology was considered
good, macroinvertebrate communities and physical form rated as moderate, riparian
vegetation and native fish communities were rated as very poor (Murray-Darling Basin
Authority [MDBA] 2012b). Additional pressures from introduced species, as well as other factors
such as increased fishing pressure and habitat degradation, have resulted in the population
densities of native fish being significantly lower than historical levels (NSW Office of Water 2010).
10
The lack of high velocity flows in the Peel system has resulted in in-stream gravel becoming
immobile and encrusted with filamentous algal mats and biofilms during summer (Foster 2004,
Foster and Lewis 2009). As a consequence the river channel has narrowed and been invaded
by riparian vegetation. In 2010–11, drought-breaking inflows commenced and flows across the
valley continued into 2011–12. Consecutive years of widespread flooding and overbank flows
contributed to significant longitudinal and lateral connection of river channel and fringing
wetlands, which would have provided breeding and recruitment opportunities for aquatic
species and contributed to condition improvements.
In the 2012–13 water year rainfall fell to below the historical average, providing the driest year
since 2006. Regional differences meant that rainfall in the western part of the catchment was
significantly lower than average, while above average rainfall was recorded in the
catchment’s east, with December 2012 to March 2013 being consistently above average.
Of the three moderately high flow events, the first occurred in late July 2012, with
approximately 30 000 ML/day passing Gunnedah and Mollee. Two smaller events occurred in
late January and early March 2013, with maximum daily flows of approximately 22 000 and
17 000 ML respectively (Burrell et al. 2014). Late winter to early summer was particularly dry,
and the warmest period on record for NSW occurred during July–October.
Some areas, such Lake Goran, an isolated ephemeral watersource near Gunnedah, retained
water from the previously wet period and continued to provide drought refuge values into
spring 2013. At least 27 ducks, colonial nesting waterbirds and shorebirds were recorded there
in October 2013.
In March 2014, good rainfall occurred across much of NSW, with nearly 70 per cent of the state
receiving above average rainfall. The good rainfall has been sporadic with the north west and
far west receiving lighter, patchier falls. Combined with mild to warm temperatures, the rainfall
boosted vegetation growth in some areas. As conditions are expected to continue to dry,
water dependent species will continue to require support to ensure their survival over coming
years and to continue to improve their condition and resilience to drought.
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3.Water availability
3.1.
Commonwealth environmental water holdings in the Namoi River Valley
for 2014–15
Commonwealth environmental water holdings available for use in 2014–15 in the Namoi River
Valley are shown in Table 3 below.
Table 3: Commonwealth environmental water holdings in the Namoi River as at 31 May 2014.
Entitlement type
Entitlement held
(GL)
Long-term
average annual
yield (GL)
Estimated
carryover
from
2013–14 (GL)
Forecast
water
availability
for
2014–15 (GL)1
Upper
(general
security)
Namoi
0.1
0.1
0
6–14
Lower
(general
security)
Namoi
6.9
5.3
6
Peel
(general
security)
1.1
0.2
N/A
Total
8.1
5.6
6
(Up to 8.6
available for use
within limits.)
0.1–0.6
Notes:
1. Forecasts are based on the best available information including state forecasts and
historical inflow scenarios. Forecasts include carryover from 2013–14. Forecasts for
regulated catchments are given to the nearest whole gigalitre except where the
entitlement held by the Commonwealth is below 1 GL.
The full list of Commonwealth environmental water holdings can be found at
www.environment.gov.au/topics/water/commonwealth-environmental-water-office/aboutcommonwealth-environmental-water/how-much and is updated monthly.
Portfolio management updates for the Commonwealth’s environmental water holdings are
available at www.environment.gov.au/topics/water/commonwealth-environmental-wateroffice/portfolio-management/portfolio-management.
3.2.
Other sources of environmental water allocations
There are currently no other sources of held environmental water in the Namoi River Valley.
3.3.
Natural or unregulated flows and planned environmental water
In addition to water entitlements held by the Commonwealth, 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 Bureau of Meteorology provides a seasonal streamflow forecasting service, which
estimates the potential for low, median or high flows for the coming three months ahead.
The Water Sharing Plan for the Upper Namoi and Lower Namoi Regulated Water Sources (2004)
provides for planned environmental water and stock and domestic (replenishment flows)
releases. Water deliveries to meet irrigation orders may provide baseflows in some sections of
12
the Namoi River. Supplementing releases with Commonwealth environmental water may
increase the potential for environmental objectives to be achieved and assist with delivery
efficiency. The Peel Water Sharing plan has provision for a stimulus flow of 1 600 ML to be
released under certain conditions. Once the capacity of Chaffey Dam has been increased
the stimulus flow will be replaced by a 5 000 ML Environmental Contingency Allowance.
13
4. Planning for water use in the Namoi River
Valley in 2014–15
4.1.
Planning for a range of inflows in 2014–15
In addition to influencing opportunities, constraints and risks in relation to environmental
watering (see Table 2), 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) 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. The Bureau of Meteorology provides a quarterly seasonal streamflow forecasting
service, which estimates the potential for low, median or high flows. As shown in Table 3,
carryover from 2013–14 for the Namoi is likely to be approximately 6.1 GL, with forecast early
season allocations (up to 31 July 2014), a total allocation range of approximately 6–7 GL is
expected to be available for use in early 2014–15.
Consideration of this allocation range relative to the total entitlement volume (Table 3) and the
full range of inflows that may be possible suggests that resource availability early in 2014–15
may be low to high, but not very low or very high. From this starting point, the full range of
possible inflows suggests that resource availability over the course of the year could be
between very low and very high (Figure 2). As such, the water use options described in Section
5 have been considered for the full range of resource availability. NSW State Water
Corporation (NSW SWC) has advised that a Bulk Release delivery strategy will be applied in the
Namoi River Valley for 2014–15. While the current resource availability has been assessed as
moderate, some options developed for this scenario may not be pursued due to delivery
constraints.
Figure 2: How inflows may vary and impact on water resource availability over the course of
2014–15 in the Namoi River Valley, from a starting point of low to high resource availability.
14
4.2.
Implementing watering actions throughout the year
Resource availability will change over the course of 2014–15 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
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 5 to be refined for implementation as required.
15
5. Water use options for 2014–15
5.1.
Summary of watering options
Watering options for 2014–15 for the Namoi and Peel rivers, reflect the approach to supply
Commonwealth environmental water to contribute to the overall environmental objectives
under the Basin Plan’s environmental watering plan.
These watering options have been designed to specifically enable the scaling of actions
across potential very low to high inflow scenarios. This provides flexibility for water use to best
complement natural inflows. Options have not been developed for very high inflow scenarios
(and the relevant resource availability). During very high inflows, unregulated flows are likely to
meet ecological objectives and (given the small quantity of holdings in the short-term) there is
likely to be limited need for and effectiveness from deliveries of Commonwealth environmental
water under this scenario.
Broadly, the aim of Commonwealth environmental watering in the Namoi and Peel rivers
during 2014–15 will be to support in-stream outcomes, with a focus on the ongoing
environmental recovery that commenced following the breaking of the drought (see
Section 2.3).
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.
Feedback has been sought during the development of water use options for 2014–15 using
existing state frameworks, for example, Environmental Water Advisory Groups and State Water
Customer Service Committees. This feedback has been incorporated into the water use
options where appropriate, particularly in relation to implementation risks and opportunities to
improve outcomes through environmental water delivery.
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.
16
Table 4: Summary of potential water use options for the Namoi River Valley in 2014–15.
Applicable level(s) of
resource availability
(see Section 4)
Very Low
Option 1 – Namoi River
Fresh Flow
Option unlikely to be
pursued under this resource
availability.
Option 2 – Namoi River
Base Flow
Contribute to base flow to flush and maintain healthy habitats in river pools and provide
greater access to a range of in-stream habitats and at times of very low flow, critical
habitat.
Option 3 – Peel River InStream Fresh Flow
Option 4 – Peel River Base
Flow
Low
Moderate
High
Contribute to fresh flows to improve the health of in-stream habitat and water quality
and to support native aquatic species by providing improved opportunities for fish to
access breeding habitat and to feed and shelter.
Option unlikely to be pursued under this resource
availability.
Option unlikely to be
pursued under this
resource availability.
Contribute to fresh flows to improve the health of instream habitat and water quality and to support native
aquatic species by providing improved opportunities for
fish to access breeding habitat and to feed and shelter.
Contribute to base flow to flush and maintain healthy habitats in river pools and provide
greater access to a range of in-stream habitats and at times of very low flow, critical
habitat.
Option unlikely to be
pursued under this
resource availability.
Note: Under certain resource availabilities, options may be not 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 to deliver environmental water.
17
5.2.
Assessment of environmental watering options
Option 1 – Namoi River Fresh Flow
Catchment: Namoi
Complex: Namoi Catchment River Flows
Site: Lower Namoi River channel
Applicable level(s) of resource availability: Low to High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh flows
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of the option is to enhance in-stream flows by contributing to rain generated
fresh flows or the delivery of other sources of water along the Namoi River to the end of the
system. This will contribute to the health of in-stream habitat and water quality, as well as
support ecological processes within the Namoi River. Connecting and extending the
wetted period of floodplain and wetland habitat with the main channel will contribute to
nutrient and food production for the aquatic ecological community.

The provision of Commonwealth environmental water in combination with unregulated
freshes will support native fish body condition, growth and reproduction by providing
increased food availability, improved opportunities for fish to access breeding habitat and
to feed and shelter. Consideration will be given to augmenting other flows in the Namoi
system (e.g. irrigation water deliveries).

The option has the potential to improve food web structure and habitat, benefitting large
bodied native fish including the EPBC listed Murray cod, as well as small bodied native fish,
including threatened species such as the purple spotted gudgeon.

To achieve this outcome, Commonwealth environmental water may contribute to
unregulated fresh event(s) that exceed 4 500 ML/day at Narrabri or 1 800 ML/day
downstream of Duncan’s Junction by maintaining flows for as long as possible with a
managed rate of fall to baseflow rates. Should environmental water be used to augment
other flows in the system flow rates would need to be determined based on the best
information at the time of the release.
Timing
Anytime (most likely late winter to summer)
Volume of Commonwealth
environmental water
Up to 8.7 GL1 (depending on available allocation)
Action undertaken in this catchment
previously:
Similar action has been undertaken elsewhere
in the Murray Darling Basin:
Note: The Annual water use limit in the Namoi Water Sharing Plan is 125 per cent of entitlement. Actual
water use will be based on the available water in accounts at the time up to the water use limit.
1
18
Yes
No
Yes
No
Operational considerations and feasibility:

Under natural conditions, rain generated fresh flows contribute to improvements in
ecological function within the Namoi River associated with carbon inputs from runoff and
high flows inundating benches and connecting anabranches. Preference will be for
Commonwealth environmental water to supplement natural flows rather than regulated
releases.

Increasing the duration of unregulated freshes that exceed 1 800 ML/day downstream of
Duncan’s Junction is likely to improve nutrient and carbon cycling and provide greater
availability to habitat by wetting banks, benches and bars present in the lower Namoi River
channel.

Consideration may be given to augmenting regulated releases to increase peak flows in
the river and to provide a more natural recession rate.

Depending on the timing of the event, certain aquatic species will be advantaged
according to their biological requirements and as conditions develop the flow regime and
objectives targeted will be refined. Deliveries in August–September may contribute to prespawning migration opportunities. Deliveries during spring to summer may support
reproduction cues or larval/juvenile dispersal.

Water orders will be developed in conjunction with NSW State Water Corporation (NSW
SWC) to ensure operational feasibility and the achievement of environmental objectives.

Should special delivery arrangements be introduced in response to very dry conditions,
such as the block release of irrigation orders, environmental water may be used to
augment these releases to provide hydrological connectivity to the end of the system.

Consideration will also be given to coordinating delivery such that return flows are used to
contribute to downstream outcomes, namely longitudinal connectivity (especially under
very low to low resource availability where end of catchment discharge would otherwise
be negligible).
Stakeholder feedback:

No specific feedback received.
19
Option 2 – Namoi River Base Flow
Catchment: Namoi
Complex: Namoi Catchment River Flows
Site: Lower Namoi river channel
Applicable level(s) of resource availability: Very Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh flows
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of the option is to: provide flows to refresh or provide hydrological connectivity
to in-stream habitat; ensure the persistence of pools as refuge; and reduce the risk of
degrading water quality conditions.

The proposed option would occur after a protracted period of low flows to maintain
essential refuge habitat for aquatic species.

To achieve this outcome, Commonwealth environmental water will contribute to low flow
base flows at Bugilbone. The precise rate will be determined based on antecedent
conditions and flows through the season. Commonwealth environmental water will be
delivered as in-channel flows from Keepit Dam and managed within the normal water
delivery arrangements.

Consideration may also be given to providing low flow base flows in the Manilla River below
Split Rock Dam, if required, to maintain critical refuge. The Commonwealth holds 104 ML of
General Security entitlement in the Upper Namoi River.
Timing
Anytime in 2014–15
Volume of Commonwealth
environmental water
Up to 8.72 GL (depending on available allocation).
(Up to 0.1 GL could be used in the upper Namoi River)
Action undertaken in this catchment
previously:
Yes
Similar action has been undertaken elsewhere
in the Murray Darling Basin:
No
Yes
No
Operational considerations and feasibility:

Under a sustained low inflow scenario, Commonwealth environmental water deliveries
could contribute to maintaining natural water levels in pools and flowing water in channel
to keep in-stream habitat wet, improve water quality, and provide drought refuge for a
range of aquatic species. The presence or absence of critical habitat or drought refuge
Note: The Annual water use limit in the Namoi Water Sharing Plan is 125 per cent of entitlement. Actual
water use will be based on the available water in accounts at the time up to the water use limit.
2
20
habitat is the key factor influencing aquatic species.

This option could be delivered by supplementing other water sources, such as planned
environmental water or irrigation deliveries, to provide longitudinal hydrological
connectivity and extend the duration of access to a range of habitats.

Should special delivery arrangements be introduced in response to very dry conditions,
such as the block release of irrigation orders, environmental water may be used to
augment these releases to provide hydrological connectivity to the end of the system.

Consideration will also be given to coordinating delivery such that return flows are used to
contribute to downstream outcomes, namely longitudinal connectivity (especially under
very low to low resource availability where end of catchment discharge would otherwise
be negligible).

The Commonwealth holds 104 ML of General Security entitlement in the upper Namoi.
Under an extreme dry scenario this small entitlement could be used in the Manilla River
downstream of Split Rock Dam to flush and maintain critical refuge.
o
The effectiveness of such action may be limited by the volume of Commonwealth
environmental water held in the upper Namoi and the ability to release water from
Split Rock Dam at low storage levels.
o
The Commonwealth entitlement in the upper Namoi is not currently linked to any
approved works. The entitlement will need to be linked to an existing works approval in
the upper Namoi prior to it being used in this section of the system.
Stakeholder feedback:

The Split Rock Water Users Association raised concerns that should Split Rock Dam be
drawn down to very low levels there may be a need to maintain connectivity and critical
refuge in the Manilla River between Split Rock and Keepit Dams. The Office has
incorporated this suggestion into the 2014–15 water use options.
21
Option 3 – Peel River In-Stream Fresh Flow
Catchment: Namoi
Complex: Other Namoi Catchment Sites
Site: Peel River
Applicable level(s) of resource availability: Moderate to High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh flows
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of the option is to contribute to in-stream fresh flows to improve ecological
function, habitat condition and mobilise fine sediment. This will contribute to the structure
of in-stream habitat, water quality and support ecological processes within the Peel River.

Connecting and extending the wetted period of habitat with the main channel will
contribute to improvements in riparian vegetation condition and food production for the
aquatic ecological community. The mobilisation of fine sediment below Chaffey Dam will
improve stream substrate habitat condition for macro invertebrate communities.

Commonwealth environmental water would be released in conjunction with an in-stream
fresh or other water sources, such as tributary flows or a Water Sharing Plan stimulus flow.
Use of Commonwealth environmental water could contribute to the scouring of the river
bed to remove periphyton and aquatic macrophytes and re-working the channel to
improve in-stream habitat condition.
Timing
Anytime (most likely late winter to summer)
Volume of Commonwealth
environmental water
Up to 1.1 GL (dependent on allocation announcements)
Action undertaken in this catchment
previously:
Yes
Similar action has been undertaken elsewhere
in the Murray Darling Basin:
No
Yes
No
Operational considerations and feasibility:

Water will be delivered into the Peel River via Chaffey Dam. The delivery arrangement in
this catchment involves water orders being submitted to NSW SWC by the Office. Water
delivery will be undertaken by State Water Corporation.

The stimulus flow out of Chaffey Dam is only available when storage conditions are met. A
stimulus flow may not be triggered in 2014–15. Should a stimulus flow not be triggered,
releases will be timed to take advantage of other flows in the system, such as downstream
tributary inflows or delivery/transfer of other sources of water.
Stakeholder feedback:

Peel Valley Water Users Association raised concerns over flooding in the Peel Valley. Prior
to any watering action being approved the Office conducts a detailed assessment of risk
and measures that can be taken to minimise any risks.
22
Option 4 – Peel River Base Flow
Catchment: Namoi
Complex: Other Namoi Catchment Sites
Site: Peel River
Applicable level(s) of resource availability: Very Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh flows
Wetland inundation
Bank-full flows
Over-bank flows

The purpose of the option is to provide low flow base flow variability to contribute to
maintaining the ecological health and resilience of the Peel River system and to refresh or
provide hydrological connectivity to in-stream habitat, ensure the persistence of pools as
refuge, and reduce the risk of degrading water quality conditions.

The freshwater environment of the Peel Valley is comprised of a range of aquatic habitats,
including extensive in-stream pool habitats, small flood runners, anabranches, benches,
point gravel bars and terraces. The aquatic habitat in the Peel supports a diverse assembly
of species, including threatened fish, frogs, and bird species.

The proposed option would occur after a protracted period of low flows to maintain
essential refuge habitat for aquatic species.

To achieve this outcome, Commonwealth environmental water will contribute to low flow
base flows below Chaffey Dam. The precise rate will be determined based on antecedent
conditions and flows through the season.
Timing
Anytime in 2014–15
Volume of Commonwealth
environmental water
Up to 1.1 GL (dependent on allocation announcements)
Action undertaken in this catchment
previously:
Yes
Similar action has been undertaken elsewhere
in the Murray Darling Basin:
Yes
No
No
Operational considerations and feasibility:

Water will be delivered into the Peel River via Chaffey Dam.

The delivery arrangement in this catchment involves water orders being submitted to NSW
SWC by the Office. Water delivery will be undertaken by NSW SWC in accordance with its
statutory requirements as a river operator.
Stakeholder feedback:

No specific feedback received.
23
5.3.
Options contributing to the Basin Annual Environmental Watering
Priorities
Each year the Murray-Darling Basin Authority develops Basin annual environmental watering
priorities (‘Priorities’). All environmental watering in the Murray-Darling Basin, including the use
of both held and planned environmental water, is to be undertaken having regard to the
Priorities.
The Priorities are not an exhaustive list of all important assets and functions throughout the Basin
and hence do not exclude other watering actions undertaken by environmental water holders
and managers.
The 2014–15 Basin annual environmental watering priorities were published on 30 June 2014
and are available here: www.mdba.gov.au/what-we-do/environmental-water/environmentalwatering-priorities/priorities-14-15. Table 5 identifies the relevant Priorities for the Namoi River
Valley and the watering options that could contribute to achieving the identified outcomes.
Table 5: 2014–15 Basin annual environmental watering priorities for the Namoi River Valley
2014–15 Basin annual environmental watering
priorities relevant to the Namoi River Valley
Watering options that may contribute to the
achievement of priority outcomes
Theme: Enhance and protect refuge habitat
Native fish in the northern Basin: Improve
survival of native fish populations by
enhancing and protecting dry period refuge
habitat in the northern Basin
Option 1 – Namoi River Fresh Flow
Option 2 – Namoi River Base Flow
Option 3 – Peel River In-Stream Fresh Flow
Option 4 – Peel River Base Flow
24
6. Accounting for the use of Commonwealth
environmental water
6.1.
Water use accounting
In the Namoi the Office is responsible for making arrangements to deliver environmental water
with the river operator NSW SWC.
River flows will be accounted for at storages or at downstream flow gauges and will be
reported to the Office by NSW SWC.
6.2.
Monitoring
6.2.1. Operational monitoring
Operational monitoring is monitoring that helps assess whether water has been delivered as
planned [e.g. the volumes, timing (frequency and duration), and 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
Namoi River Valley, this includes NSW SWC, NSW Office of Water and NSW Department of
Primary Industries.
Delivery partners provide regular operational monitoring updates to the Office. The operational
monitoring requirements are set out in the Office’s 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.
6.2.2. Long term intervention monitoring
The Long Term Intervention Monitoring Project (LTIM Project) is the primary means by which the
Office will undertake monitoring and evaluation of the ecological outcomes of
Commonwealth environmental watering. The LTIM Project will be implemented at seven
Selected Areas over a five year period from 2014–15 to 2018–19 to deliver five high level
outcomes (in order of priority):
1. evaluate the contribution of Commonwealth environmental watering to the objectives of
the MDBA’s Environmental Watering Plan
2. evaluate the ecological outcomes of Commonwealth environmental watering at each of
the seven Selected Areas
3. infer ecological outcomes of Commonwealth environmental watering in areas of the
Murray-Darling Basin that are not monitored
25
4. support the adaptive management of Commonwealth environmental water
5. monitor the ecological response to Commonwealth environmental watering at each of the
seven Selected Areas.
This approach has a sound scientific basis that allows the Office to understand environmental
outcomes in catchments where around 90 per cent of Commonwealth environmental water is
held. A Monitoring and Evaluation Adviser will undertake evaluation at the Murray-Darling Basin
scale.
The seven Selected Areas where monitoring will occur are:
1. Junction of the Warrego and Darling rivers
2. Gwydir River system
3. Lachlan River system
4. Murrumbidgee River system
5. Edward-Wakool River system
6. Goulburn River
7. Lower Murray River.
These areas were chosen to be representative of Commonwealth environmental watering
across the Murray-Darling Basin.
The results from the LTIM Project can be used to infer ecological outcomes of Commonwealth
environmental watering in the Namoi River Valley catchment.
Results from the LTIM Project will be published on the Office’s website and the data will be
publicly available.
26
7. Next steps – from planning to water
delivery
Local knowledge and experience is critical to effectively manage and deliver Commonwealth
environmental water. Stakeholders have an important role and provide critical information that
informs each stage of the process for managing Commonwealth environmental water (see
Figure 3).
The planning phase is the first stage in the cycle of environmental water management. The
planning process occurs on an annual basis between January and the end of June, and each
planning document represents the culmination of months of work and consultation.
Throughout the planning process the Office consults closely with state environmental water
managers, river operators and local environmental water advisory groups. The information
gathered as part of the planning process feeds into the development of the options for the
following water year.
Towards the beginning of the new water year the focus shifts from planning to implementation.
Greater consideration is given to current and forecast catchment conditions and water
availability to determine which of the options identified during the planning process can
feasibly be implemented. Local on-ground knowledge is important for detailing a specific
watering action including the flow magnitude, timing, triggers for commencement, rates of rise
and fall and the area to be inundated. Once an action has been scoped in more detail an
assessment against the following criteria is undertaken:

ecological value of the river, floodplain or wetland

expected outcomes from watering

potential risks of watering

long-term sustainability and management of the site

cost effectiveness and feasibility of watering.
Site managers and local community groups provide important information to inform these
assessments. In particular, information related to potential risks provides critical input to the
detailed risk assessment that is undertaken before a decision is made on a watering action. For
further information see the Framework for Determining Commonwealth environmental water
use (available at: www.environment.gov.au/topics/water/commonwealth-environmentalwater-office/assessment-framework).
Following the scoping and assessment of potential watering actions, the Commonwealth
Environmental Water Holder is required to make a decision on whether or not to commit the
water and funds required to support the watering action. In doing so the Commonwealth
Environmental Water Holder also has regard to the Basin Annual Priorities as required by the
Basin Plan.
When a decision is made by the Commonwealth Environmental Water Holder to proceed with
a watering action arrangements for implementation are made with delivery partners. This
includes river operators, who manage the delivery of the water and operational monitoring.
Local community involvement is crucial at this stage of implementation and during water
delivery as conditions can change rapidly and may result in the need to adjust, suspend or
even cancel the watering action.
27
Upon completion of the watering action, a review process, which generally takes place from
March through to October, informs future watering actions and long-term management. This
review is informed by the weekly operational monitoring, results of ecological monitoring, and
feedback provided by site managers and the local community.
IMPLEMENTATION
Detailed planning and
scoping of feasible
watering actions
Approval of Water
Use Options
documents by CEWH
Preparation of
paperwork for decision
includes assessment
against criteria
Assessment of
catchment conditions
Eliminate
unrealistic/
unfeasible
options
Detailed risk assessment
Decision by CEWH
Change, suspend or
cancel watering
actions to reflect
changing conditions
REVIEW
Implementation of
watering action
Ongoing weekly
operational monitoring
Watering action
finished – acquittal
report
Stakeholder input to CEWO required
Mar - Oct 2015
Annual planning for
Commonwealth
environmental water
use options
Jun 2014- Jun 2015
Jan– Jun 2014
PLANNING
Completion of all
watering actions within
a catchment –
Watering Action
Review
Ecological monitoring:
• Short term ecological
monitoring by other
agencies
• Long Term
Intervention Monitoring
Figure 3: The annual management process for Commonwealth environmental water.
28
8.Partnerships
The Office has consulted with a range of stakeholders to develop the Commonwealth
environmental water use options for the Namoi River Valley for 2014–15, including our delivery
partners as follows:

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

North West Local Land Services

State Water Corporation

Namoi Water.
The Office will continue to work with stakeholders and other interested community members in
the planning, delivery, management and monitoring of Commonwealth environmental water.
29
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to the Murray-Darling Basin Authority, Canberra.
Banks, R.G. (1995). Soil Landscapes of the Curlewis 1:100 000 Sheet Report. Department of
Conservation and Land Management, Sydney.
Barma Water Resources, Thurtell, L. and Wettin, P. (2012). Environmental Water Delivery: Namoi
River. Prepared for Commonwealth Environmental Water, Department of Sustainability,
Environment, Water, Population and Communities, Canberra.
Boys, C. Miles, N. and Rayner, T. (2009). Scoping options for the ecological assessment of cold
water pollution mitigation downstream of Keepit Dam, Namoi River. MDBA Publication No.
20/09.Murray-Darling Basin Authority, Canberra.
Burrell M., Moss P., Petrovic J., Ali A., (2014) General Purpose Water Accounting Report 20122013: Namoi Catchment, NSW Department of Primary Industries, Sydney
CSIRO (2007). Water availability in the Namoi. Summary of a report to the Australian
Government from the CSIRO Murray-Darling Basin Sustainable Yields Project, December 2007.
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Davies, P.E., Harris, J.H., Hillman, T.J. and Walker, K.F. (2008). SRA Report 1: A Report on the
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Wetlands Database: Directory of Important Wetlands. [online] available:
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Catchment description. Department of Sustainability, Environment, Water, Population and
Community, Canberra.
Eco Logical Australia (2008). Namoi Wetland Assessment and Prioritisation Project. (Project No.
125-005) Draft report prepared for Namoi Catchment Management Authority, September
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30
Green, D., Petrovic, J., Moss, P. and Burrell, M. (2011). Water resources and management
overview: Namoi catchment. NSW Office of Water, Sydney
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Arts, Canberra.
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Large Lowland Riverine Landscape. PhD Thesis, University of Canberra, Australia.
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Namoi River Valley. Cooperative Research Centre for Freshwater Ecology. Prepared for the
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31