Annual Plan for the Snowy and Montane River Increased Flows 2019–20

DEPARTMENT OF PLANNING, INDUSTRY & ENVIRONMENT Annual Plan for the Snowy and Montane River Increased Flows 2019–20

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Contents

1. Introduction 1 2. Objectives for Snowy River Increased Flows 3 3. Natural flow scaling of Snowy River Increased Flows 4 4. Snowy River Increased Flows in 2019–20 6 5. Snowy Montane Rivers Increased Flows 10 6. Snowy Montane Rivers Increased Flows in 2019–20 12 7. Monitoring and ecological constraints on river recovery 14 8. Complementary measures 15 9. Social, cultural and economic considerations 15 10. References and further reading 16

iii

List of tables

Table 1 Summary of annual water allocation to the Snowy River 6 Table 2 SMRIF allocations and settings for 2019–20 as adjusted 12

List of figures

Figure 1 The Snowy River catchment in south-eastern Australia, showing the location of Jindabyne Dam, major tributaries and hydrological gauging stations 2 Figure 2 Annual flow duration curves for the pre-regulation Snowy River, the post-regulation Snowy River, Snowy River Increased Flows (SRIF) and the Thredbo River 4 Figure 3 Monthly instantaneous maximum flows for the Snowy River at Dalgety Weir 1997–2019 5 Figure 4 Snowy River below Jindabyne mean daily discharge pattern for 2019–20, with one primary (X) and four secondary eight-hourly flow peaks (A, B, C, D). 7 Figure 5 Planned release rate steps for the October 2019 flushing flow event below Jindabyne Dam 8 Figure 6 Snowy River below Jindabyne Dam total monthly discharge pattern for 2019–20 9 Figure 7 Locations of the Snowy montane rivers water release points – indicated by green icons, and a pie chart of flow volumes for the three increased flows 11 Figure 8 2019–20 SMRIF flow pattern for the Upper Murrumbidgee River below Tantangara Dam. 13

iv Annual Plan for the Snowy and Montane River Increased Flows 2019–20

1. Introduction

The Snowy Water Initiative (SWI) was formally established in 2002 to achieve significant improvements in river health by releasing environmental water into the Snowy, upper Murrumbidgee, and upper Murray river systems. Embodied in the Snowy Water Inquiry Outcomes Implementation Deed 2002 (SWIOID 2002), the SWI is an agreement for water recovery and environmental flows between the NSW, Victorian and Australian governments (the partner governments) and Snowy Hydro Limited. The NSW Government is responsible for the implementation of the SWI.

The SWI provides for three increased environmental water flow regimes to adjust for the diversion of river flows by the Snowy Hydro-electric Scheme:

1. Snowy River – environmental water to be released every day from Jindabyne Dam (Figure 1) as Snowy River Increased Flows (SRIF), to improve the health of the Snowy River in New South Wales and Victoria 2. Snowy montane rivers – environmental water to be released continually or according to an annual schedule from a number of designated release points across certain rivers diverted by the Snowy Mountains Scheme as Snowy Montane Rivers Increased Flows (SMRIF) (Figure 7), in a quantity proportional to the amount allocated to the Snowy River below Jindabyne 3. River Murray – water allocation accruing to 70 gigalitres (GL) of entitlement in the Murray River system that is callable by environmental water holders as River Murray Increased Flows (RMIF) for delivery into the Murray River.

This strategy outlines the rationale and intention for increased flows for the Snowy and Snowy montane rivers for the 2019–20 water year (1 May 2019 to 30 April 2020), and gives effect to the NSW Government’s commitment to implement the SWI on behalf of the partner governments.

1 Annual Plan for the Snowy and Montane River Increased Flows 2019–20

Figure 1 The Snowy River catchment in south-eastern Australia, showing the location of Jindabyne Dam, major tributaries and hydrological gauging stations

2 Annual Plan for the Snowy and Montane River Increased Flows 2019–20

2. Objectives for Snowy River Increased Flows

In determining how to use the environmental water in the Snowy River below Jindabyne Dam the partner governments agreed that a primary ecological objective would be achieved by storing and then releasing sufficient volumes to provide annual flushing flows and occasional channel maintenance flows. Flushing flows scour and transport finer sediment (sand, silt and clay) and improve the physical condition of the instream river channel habitat and overall river health. Channel- forming flows scour larger sediments (gravel and cobbles) and define a channel pathway within the overall river bed. It is expected that as the river physically responds over time to these higher energy flows, the recovery process can transition to meet other secondary ecological objectives. The SWIOID 2002 sets out five key environmental objectives for the SRIF: 1. improving the temperature regime of river water 2. achieving channel maintenance and flushing flows within rivers 3. restoring connectivity within rivers for migratory species and for dispersion 4. improving triggers for fish spawning 5. improving the aesthetics of currently degraded riverine environments. These objectives have been further developed with new information to better define the aspects of riverine health that are key to the recovery of a geomorphologically confined Snowy River. Aquatic biota are adapted to local climatic and hydrological conditions and being able to represent the varied characteristics of the local hydrology is therefore a key driver to river recovery from flow diversion. The focus of this strategy is to provide the flow-related river processes that will support: • diverse habitats • increased resource availability and biological productivity • enhanced biological reproduction and recruitment • increased connectivity and dispersal within and along the river channel. Over time in the Snowy River, this should develop the hydrological characteristics of a smaller montane river with daily flow variability and a seasonal snowmelt flow pattern, and with instream habitats that are improved by an increase in the wetted area within the river channel, an increase in the open water habitat, an increase in hydraulic diversity within the river channel, and greater frequency of water mixing within in-channel habitats. In turn, this is expected to support an improved range of biota consistent with this river type.

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3. Natural flow scaling of Snowy River Increased Flows

A ‘natural flow scaling approach’ (Reinfelds et al. 2013) has been used to deliver environmental water to the Snowy River below Jindabyne Dam since 2013–14, when 212 GL of water entitlement for the Snowy River was achieved for the first time since the SWI commenced. The volume of water available for environmental flows in the Snowy River is approximately equivalent to annual natural flow in the Thredbo River (Figure 2). A practical interim objective using the natural flow scaling approach has been to deliver a flow regime that, over the long term, will drive the hydraulic geometry of the Snowy River below Jindabyne Dam to be more like the Thredbo River as river channel sediment is mobilised and redistributed. The primary advantage of natural flow scaling is that the pattern of the flow regime is proportional to the volume of available environmental water. Peak flood magnitudes and duration can be tailored to achieve flow transmission and ecosystem objectives, and the flow regime mimics daily, seasonal and annual patterns in flow variability. This approach also provides a secure operational flow forecast that Snowy Hydro Limited can plan for and deliver. The natural flow scaling approach recognises that with only up to 21% of the natural flow available, restoring any single aspect of the pre-regulation Snowy River flow regime could compromise other aspects of the flow regime and not optimise river health. Even the lowest annual discharge recorded in the Snowy River at Jindabyne before the dam and river diversion is approximately double the total volume of water available for environmental flows (Reinfelds et al. 2013).

Figure 2 Annual flow duration curves for the pre-regulation Snowy River, the post- regulation Snowy River, Snowy River Increased Flows (SRIF) and the Thredbo River

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Monthly maximum discharge data for the Snowy River below Jindabyne Dam (at Dalgety Weir) show a clear step-change increase in the magnitude and frequency of high flows from 2011 (Figure 3). The higher flow regime was reintroduced at this time after the attainment of 212 GL of water entitlement (licences) and post the Millennium Drought. Under the natural flow scaling approach, the high flow releases from Jindabyne Dam have peak flow rates that range from approximately 2000–13,000 megalitres per day (ML/d) (Figure 4). These peak flow rates replicate peak flow rates for annual maximum one-year to 10-year recurrence interval winter–spring floods in the Thredbo River (Reinfelds et al. 2013).

Figure 3 Monthly instantaneous maximum flows for the Snowy River at Dalgety Weir 1997–2019 The 38,600 ML/d flow peak in March 2012 resulted from a natural flood spilling from Jindabyne Dam.

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4. Snowy River Increased Flows in 2019–20

SRIF annual allocations are determined by inflows into the western catchment storages where Snowy water savings projects and market purchases were implemented. These projects, funded by the NSW and Victorian governments, obtained water shares that were then transferred to Snowy environmental water licences. The water allocated to the SRIF licences in one year is then made available for environmental releases from Snowy storages in the following year. Planning for the forward year commences around December of each year when the indicative volume of water available on the licences can begin to be forecast. Drought conditions have severely affected allocations to the SRIF licences in 2018–19. This will require environmental flow volumes in 2019–20 to be reduced, although the flow scaling pattern will be broadly retained. There are 110,171 ML available from these SRIF licences for 2019–20, which is half of the 21% mean annual flow targeted for release below Jindabyne Dam (Table 1). This reduced volume represents the allocation that accrued to SRIF licences in the 2018–19 year. Note that the SRIF amounts add to a base passing flow (BPF) amount of 8500 ML released from Jindabyne Dam. Adjustments of the base passing flow amount are required when the amount of water released in the previous year was more than (overs) or less than (unders) the agreed flow volume. That amount is then corrected with changes to actual releases in the following year by reducing or increasing the 8500 ML figure.

Table 1 Summary of annual water allocation to the Snowy River

Water account Annual volume (ML)

SRIF 110,171 BPF – Jindabyne 8,500 Sub-total 118,671

Overs/Unders* 0 Total* 118,671*

*Volume is amended following the review of target achievement of the previous water year. Amendment: an over release of 800 ML for the 2018–19 water year was notified in September 2019. Volumes in 2019–20 have been reduced accordingly, making the total available 117,871 ML.

The 2019–20 SRIF strategy marks the seventh year of using the natural flow scaling approach to develop the environmental water release strategy for the Snowy River below Jindabyne. The proposed 2019–20 SRIF flow sequence is based on the 1997–98 water year in the Thredbo river, which had a 107 GL total flow that season. Given this relatively low allocation, the peak flow release is set at 5000 ML/d for eight hours, similar to the Thredbo River 1997–98 instantaneous maximum peak flow rate of 4742 ML/d. The highest peak in the Thredbo River in 1997–98 occurred in June. This plan (Figure 4) will provide for the best chance of a flushing flow in spring, given it was not possible to make such a release in the 2018–19 year due to low dam levels. A flushing flow may occur in any year that the annual allocation volume exceeds 100 GL. A pulse that would have otherwise been planned in October has been set to occur in June.

6 Annual Plan for the Snowy and Montane River Increased Flows 2019–20

Figure 4 Snowy River below Jindabyne mean daily discharge pattern for 2019–20, with one primary (X) and four secondary eight-hourly flow peaks (A, B, C, D). Amendment: flows from 1 to 16 October 2019 have been reduced by 50 ML/day to balance an over release of 800 ML for the 2018–19 water year.

A release rate of 5000 ML/d can be delivered without using the spillway but does rely on the Jindabyne Dam cone valves to be fully operational. To increase the likelihood the peak release can be achieved without full dependence on the cone valves, this peak flow has been set to occur in October, when it can be expected storage levels in the dam will be sufficiently high to provide or contribute to the flushing flow release rate.

Four secondary flood pulse releases (Figure 4 – A, B, C and D) are to be delivered via the Jindabyne Dam cone valves. These four events have eight-hour peak flow rates ranging from 2188–3561 ML/d. These releases will require active management by Snowy Hydro Limited to generate the eight-hour peaks and reach the overall daily target.

7 Annual Plan for the Snowy and Montane River Increased Flows 2019–20

Figure 5 Planned release rate steps for the October 2019 flushing flow event below Jindabyne Dam

The proposed shape of the flushing flow hydrograph is shown in Figure 5 and is based on SRIF volumes. A proportion of the allowed Jindabyne base passing flow volume will be used to taper the rising and falling limbs around this and the other five planned eight-hour peak flows.

Figure 6 summarises the derived total monthly discharge patterns for 2019–20 below Jindabyne Dam. A pattern of sustained higher flow rates over winter, spring and early summer reflect the winter rainfall/runoff patterns typical of a mixed rainfall and snowmelt river system characteristic of the Snowy Mountains.

Low flow periods will occur in summer and autumn, with a minimum release rate in early autumn that reflects the natural low flow period. It is recognised that this is a very basic allocation to the river for this period that will be noticeable for river users, and results from the need to retain higher energy spring flows for river channel recovery, flow scaling of the overall pattern, and low water availability in the 2019–20 water year.

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Figure 6 Snowy River below Jindabyne Dam total monthly discharge pattern for 2019–20 Amendment: flows in October 2019 have been reduced by 800 ML to balance an over release in the 2018–19 water year.

Natural tributary inflows below the junction with the Delegate River will provide the most substantial contribution to the flow regime and ecosystem processes of the lower reaches of the Snowy River and its estuary in this water year.

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5. Snowy Montane Rivers Increased Flows

The SWIOID 2002 also provides for environmental releases into a number of higher altitude (montane) rivers whose flows are significantly affected by the operation of the Snowy Scheme (the SMRIF allocation). Water is released from small weirs as a passing flow, or as managed releases from Tantangara Dam for: • Snowy River above Jindabyne Dam • Goodradigbee River • Murrumbidgee River below Tantangara Dam • Geehi River. Each release point results in a different amount of foregone generation for Snowy Hydro Limited for each megalitre of water that is released, with Snowy Hydro Limited required to forego a total generation up to a maximum of 150 gigawatt hours (GWh) each year. Each year, the degree to which generation is foregone is proportional to the volume of water allocated to the Snowy River, and if the full 212 GL target is available for the Snowy River, the full 150 GWh of generation will be foregone by Snowy Hydro Limited. As the water is either reregulated by the Snowy Scheme, or by water supply storages in the western rivers, additional water savings are not required to enable these releases. All of the targeted release points have required modification to the existing works to enable the releases to be made. This has been undertaken progressively as savings in the western rivers increased, and allowable foregone generation has increased. Releases are now occurring into most of the targeted montane rivers, although final release arrangements for the upper Snowy River near Guthega are yet to be finalised. Releases to the Murrumbidgee River are made from Tantangara Dam, a much larger structure than the other release points, and which also has a gated release facility. Tantangara releases usually comprise two components: an SMRIF amount plus a required annual base passing flow. The Tantangara base passing flow has two key operating rules required by the Snowy Water Licence: • 32 ML/d minimum river discharge maintained at Mittagang Crossing, near Cooma • 2 GL/year volume on average is targeted over the longer term. Montane releases from the other, smaller weirs reflect the catchment inflows to each weir pool and it is not practical to prescribe a daily flow target. The downstream flow from the smaller weirs reflects the hydrology of their inflows where in wetter years, the flow will exceed the long-term target, and in drier years, the annual volume will be less than the target. The SMRIF sets an annual yield so that over the long term, the annual volume will approximate the nominated increased flow target. To achieve the long-term target, each weir has been modified to either allow all water to pass downstream as ‘transparent releases’, or in the case of the Goodradigbee River, allow a proportion of the daily inflows to be ‘translucent’ releases. This is so that the flow characteristics downstream of the modified weirs will reflect the hydrology of a smaller mountain river or stream.

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Figure 7 Locations of the Snowy montane rivers water release points – indicated by green icons, and a pie chart of flow volumes for the three increased flows

The volumes identified on the pie chart in Figure 7 are an upper limit for a full allocation scenario, and thus represent a maximum that could be released in any one year. The SWIOID 2002 sets a series of ecological objectives for the Snowy montane rivers, defined broadly as to protect endangered or threatened species, maintain natural habitats, and maintain wilderness and national park values. In practice, flow-related river processes extend these objectives to include habitats, resource availability and productivity, reproduction and recruitment, and connectivity and dispersal.

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6. Snowy Montane Rivers Increased Flows in 2019–20

The SRIF allocation for 2019–20 will lead to a foregone generation value of 78 GWh for SMRIF. If the settings of the Snowy montane program weirs remain as they currently are there would not be any water to release from Tantangara. Yield from the weirs program in their current settings would equate to 80.6 GWh of foregone electricity, which is 2.6 GWh more than is allowed for. To meet the difference between the current settings and the amount of foregone generation provided for by the 2019–20 allocation (i.e. the difference between 80.6 GWh and 78 GWh) the settings on the Goodradigbee River Weir have been adjusted down. This arrangement will be maintained until overall SRIF water allocations allow full reinstatement of flows at this weir. The Goodradigbee River Weir is configured such that the adjustment that can be made from its current setting is a step that reduces undiverted flow from 12 GL to 7 GL per annum (a difference of 5 GL). Whilst this saves more water than is required to meet the generation shortfall of 2.6 GWh, it enables a more useful allocation of 3.6 GL to be made available for flows below Tantangara Dam. Under this approach the SMRIF program for 2019–20 will be as shown in Table 2.

Table 2 SMRIF allocations and settings for 2019–20 as adjusted

River Modified works GWh Average Foregone reach/catchment conversion annual flow electricity factor (GL) generation (GWh) Murrumbidgee River Tantangara Dam Outlet 1.94 3.6* 7 Goodradigbee River Goodradigbee River 1.94 7 13.6 Weir Geehi River Middle Creek Weir 1.85 22.7 42 Strzelecki Creek Weir Snowy River – Tolbar Creek Weir 0.71 18.9 13.4 Gungarlin Diggers Creek Weir Snowy River – Falls Creek Weir 0.57 3.4 1.9 Perisher/Rams Flat Total 55.6 77.9 *Amendment: an over release of 0.3 GL for the 2018–19 water year was notified in September 2019. Volumes in 2019–20 have been reduced accordingly, making the total Tantangara release 3.3 GL

Due to the low allocation available in 2019–20, a natural flow scaling approach cannot be effectively applied to the SMRIF in the Murrumbidgee River below Tantangara Dam. Instead, the pattern of flow adopted includes the key hydrological signals typical of a smaller mixed snowmelt–rainfall river system characteristic of the northern Snowy Mountains, consistent with the volume available and the dam outlet capability. The natural flow pattern of the Upper Murrumbidgee River varies from that of the Snowy River, as there are strong climatic gradients across the Snowy Mountains. Typically, the Upper Murrumbidgee River catchment is lower in elevation than the Snowy River catchment and has substantially less catchment area above the snowline, and snowmelt flow is not as pronounced as the Snowy River.

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It is not possible to achieve stream velocities or flow volumes sufficient for channel scouring or sediment movement in the upper Murrumbidgee this year, but the flow pattern will reflect some of the montane hydrological cues and will seek to provide minor protection of stream riffles in spring, as flowing water habitats are the first instream habitat to be impacted by low flow periods. This is expected to provide some protection of riffle dependent biota, such as aquatic heterotrophic bacteria and macroinvertebrates, including mayflies, caddisflies and stoneflies. The Tantangara flow pattern (Figure 8) will allow for: • a monthly flow pattern that reflects a winter–spring signal and includes four months (i.e. July–October) with total flows above 600 ML • minor daily flow variability during the winter–spring period, with flow varying between zero and 100 ML/d and with discharge of 100 ML/d on two occasions during the winter– spring period to reflect winter–spring storms • a spring pulse into the river to provide seasonal cues to instream biota including fish • a small pulse in late spring and a small pulse in mid-summer to help reduce pool stratification. Amendment: to balance the 2018–19 over-release, these pulses will no longer be delivered. However, base passing flows are likely to occur in these months.

Figure 8 2019–20 SMRIF flow pattern for the Upper Murrumbidgee River below Tantangara Dam. Amendment: to balance an over release in the 2018-19 water year, the SMRIF target have been reduced to zero for 19-20 September, 12-15 October 2019 and the November and January pulses.

There will also be six periods totalling 263 days without SMRIF releases as there is insufficient water available to maintain flows for every day of the year. During this time Snowy Hydro Limited is required to provide for base passing flows and will continue to target 32 ML/d at Mittagang Crossing.

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7. Monitoring and ecological constraints on river recovery

Monitoring of the outcomes of river recovery flows are currently in transition from an intensive benchmarking and initial flow response regime, to a fit for purpose system to test key recovery parameters of hydrology, geomorphology, vegetation and stream biota. Monitoring to date has supported visual observations that a recovery trend has been initiated in the Snowy River below Jindabyne Dam that will be maintained with the pattern of flows now being provided. More work is required to establish an agreed monitoring regime for the Snowy montane rivers. There are a number of climate and ecological factors that could constrain the achievement of river environmental flow objectives, if there is insufficient water and stream power to overcome them, including the following. Hydrology: Flow scaling provides a current best approximation to the pattern of flows required to recover and maintain the key parameters of river health in the rivers subject to SRIF and SMRIF. Current low inflows resulting from drought conditions underscore an overall risk presented by climate change to the amount of water available for flows, constraining the resulting pattern of delivery, particularly for higher energy flows required to maintain river channel condition. This will require an adaptive and informed approach to deliver the key intentions of the SWIOID 2002 and may further constrain other objectives outside of river health, including recreational use of the river. Habitat: • coatings of fine sediment and filamentous green algae on the river substrate • warmer water than in pre-diversion conditions in late autumn, winter and early spring • re-establishment of woody environmental weeds such as willows (Salix fragilis) and blackberry (Rubus fruticosus agg.) into the former river channel • poor riparian land condition eroding into rivers and arising from grazing pressures and soil damage from livestock and feral animals. Resource availability, reproduction and recruitment: • insufficient basal resources for biological productivity, e.g. dissolved organic carbon, dissolved silicon • insufficient instream nutrient transfer surfaces or habitat spaces, i.e. cobbles or large woody debris • resource competition, including with introduced species • insufficient population abundance or density to be self-sustaining. Connectivity and dispersal of aquatic plants and animals: • limited ability of desired species to disperse • limited connectivity of desired species to remnant populations • significant impediments to dispersal due to weirs, dams and natural barriers, e.g. rapids, cascades.

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8. Complementary measures

Complementary resource management activities are required to support the delivery of water and flow-based river rehabilitation objectives, as they maximise the effect of water available for environmental flows. Complementary activities typically include: • improved management of catchments to reduce fine sediment entering the river • removal of exotic weeds such as willows and blackberry to allow channel geomorphic change • livestock and feral animal management to protect in-channel habitats, riparian zones, and headwater streams and swamps • reintroduction of selected fish species lost from river reaches during total river diversion, once habitat has returned.

9. Social, cultural and economic considerations

The Snowy and Montane rivers are of great significance for their connection to a range of communities and people and this has remained a driving force behind the actions that have led to their ongoing recovery. It is important the key linkages and dependencies of communities and people to the mountain rivers are recognised and where possible, nurtured by the effective use of environmental water. These understandings will grow with increased knowledge around traditional and contemporary practices of the First Peoples’ movements following seasonal travel routes, and the availability of food. The Snowy Advisory Committee established by the NSW Government will be a primary source of advice to water managers on these relationships; cultural, social or economic. The Committee has resolved to develop a framework for supporting decisions for future advice that is broader in its application than flow scaling. The framework, consistent with the statutory requirements of the Committee, will require advice be sought for the SRIF and SMRIF allocations that is first and foremost about what is best for the environment; however, the Committee will also seek to achieve cultural, social and economic benefits where they are compatible with achieving environmental outcomes. The Committee considers that where the environmental outcome can be achieved and a social and economic benefit gained, the multiple benefits should be sought when providing advice. Most importantly, the Committee considers that the framework must be inclusive of Aboriginal culture and heritage and this aspect will be included in all advisory considerations. Over time the Committee considers that integration of these objectives will also provide guidance to more detailed flow management and monitoring activities. These understandings will grow around the central concepts of the rivers and their First Peoples, with an intention to provide for healthy rivers that support a diversity of cultural, social and economic activity. Healthy rivers recovered from a history of water diversion will remain the primary purpose of water use. The direction set by the Committee will, however, lead to better identification of river-use constraints, e.g. the availability of water that would support recreational activities, with the intention that water managers will better communicate plans, and where possible, optimise multiple benefits for river-use objectives.

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10. References and further reading Baldwin DS, Whitworth KL and Hockley CL 2014, Uptake of dissolved organic carbon by biofilms provides insights into the potential impact of loss of large woody debris on the functioning of lowland rivers, Freshwater Biology, vol.59, pp.692–702. Brooks AJ, Russell M, Bevitt R and Dasey M 2011, Constraints on the recovery of invertebrate assemblages in a regulated snowmelt river during a tributary-sourced environmental flow regime, Marine and Freshwater Research, vol.62, pp.1407–1420. Caissie D 2006, The thermal regime of rivers: a review, Freshwater Biology, vol.51, no.8, pp.1389–1406. Carr GM, Hamish CD and William DT 1997, Models of aquatic plant productivity: a review of the factors that influence growth, Aquatic Botany, vol.59, pp.195–215. Coleman D and Williams S 2016, Mobilising fine sediment in a highly regulated upland snowmelt river using hydrological scaled experimental floods, Marine and Freshwater Research, vol.67, pp.1–13. Erskine WD, Terrazolo N and Warner RF 1999, River rehabilitation from the hydrogeomorphic impacts of a large hydro-electric power project: Snowy River, Australia, Regulated Rivers: Research and Management, vol.15, pp.3–24. Gilligan D and Williams S 2008, Changes in fish assemblages after the first flow releases to the Snowy River downstream of Jindabyne Dam, Snowy River Recovery: Snowy River Flow Response Monitoring, Department of Water and Energy, Sydney. Kiffney PM, Greene CM, Hall JE and Davies JR 2006, Tributary streams create spatial discontinuities in habitat, biological productivity, and diversity in mainstem rivers, Canadian Journal of Fisheries and Aquatic Sciences, vol.63, no.11, pp.2518–2530. Poiani KA, Richter BD, Anderson MG and Richter HE 2000, Biodiversity conservation at multiple scales: functional sites, landscapes, and networks, BioScience, vol.50, no.2, pp.133–146. Reinfelds I, Williams S, Russell M, and Haeusler T 2013, Scaling environmental flow releases in the Snowy River to unregulated snowmelt rivers of the Snowy Mountains, Snowy Flow Response Monitoring and Modelling program, NSW Office of Water, Sydney. Rohlfs A 2016, ‘Rehabilitating the Snowy River: the influence of environmental organic carbon supply and utilisation’, PhD Thesis, University of Technology, Sydney, opus.lib.uts.edu.au/handle/10453/90254. Rohlfs A, Mitrovic SM, Williams S and Coleman D 2015, Can tributary in-flows improve the recovery of the dissolved organic carbon regime in a snowmelt river regulated by a large reservoir?, Marine and Freshwater Research, vol.67, no.9, pp.1338–1345. Rohlfs A, Mitrovic S, Williams S, Coleman D, Hitchcock J and Rees J 2016, Dissolved organic carbon delivery from managed flow releases in a montane snowmelt river, Aquatic Sciences, vol.78, no.4, pp.793–807. Russell M, Brooks A and Williams S 2012, The effect of Mowamba River and Jindabyne Dam environmental flow releases on macroinvertebrate assemblages in the Snowy River, 2000–2008, Snowy flow response monitoring and modelling, NSW Office of Water, Sydney. Snowy Water Inquiry Outcomes Implementation Deed 2002, www.water.nsw.gov.au/__data/assets/pdf_file/0008/547136/utilities_snowy_lic_snowy_imple mentation_deed.pdf. Van der Wal, E J 1985, Effects of temperature and salinity on the hatch rate and survival of Australian bass (Macquaria novemaculeata) eggs and yolk-sac larvae. Aquaculture, 47, 239- 244.