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Lake Eildon and Goulburn Weir have significantly modified the Goulburn River's flow pattern. Due to the impact of water harvesting, lower flows now occur in the Goulburn River in winter and spring while higher flows occur in summer and autumn due to releases to meet irrigation and consumptive demands. This reverses what would happen naturally. The river flow regime is also affected by land use changes and by the construction of small dams and drainage schemes. Levees and other structures prevent water inundating the floodplain. Tributaries downstream of major infrastructure (such as Seven Creeks and the Broken River) help contribute natural flows to the Goulburn River in the lower reaches downstream of Goulburn Weir.

Environmental water in the Goulburn system is held by the VEWH, CEWH and MDBA as part of the Living Murray program. The CEWH is the largest holder of environmental water in the Goulburn system. Availability and use of Commonwealth environmental water is critical to achieving outcomes in the Goulburn River. Environmental water held on behalf of the Living Murray program may also assist in meeting objectives in the Goulburn system en route to icon sites in the Murray system.

Environmental water may need to be delivered through the Goulburn system to meet a downstream environmental objective. Where possible, these releases are managed to achieve outcomes in the Goulburn system before being reused downstream.

Environmental targets can also be met by water delivered from Lake Eildon to meet downstream demands in the River Murray (known as inter-valley transfers). Goulburn inter-valley transfers occur at times during the irrigation season, from spring to autumn. These flows may assist in achieving the desired environmental objectives without the need to release environmental water.

The priority reaches are reaches 4 and 5 (see below) in the lower Goulburn River as they are the most flow-stressed sections of the river. Delivery of environmental flows to these target reaches also provides benefits and meets some environmental targets in upstream reaches. The use of environmental water to target objectives above the Goulburn Weir (reaches 1–3) is limited as they receive significant flows for the purpose of transferring consumptive water from Lake Eildon to Waranga Basin. These flows often meet or exceed environmental flow targets in this part of the system for most of the year.

System map

Goulburn System
Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches can receive environmental water.

Environmental watering objectives in the Goulburn River

Fish icon
Protect and boost populations of native fish (including golden perch) by providing habitat flows and encouraging fish to migrate and spawn
Insect icon
Provide habitat and nourishment for waterbugs which provide energy, break down organic matter and support the river’s food chain
Landscape icon
Maintain the form of the river bank and channel and a diversity of riverbed surfaces to support all stream life
Plant icon
Increase aquatic and flood-tolerant plants within the river channel and lower banks to provide shelter and food for organisms further up the food chain and to stabilise the river bank

Environmental values

The Goulburn River supports a range of native fish species including golden perch, silver perch, Murray cod, trout cod, Macquarie perch and freshwater catfish. Its aquatic plants and submerged logs provide great diversity of habitat to support adult and juvenile fish. Bank plants are dominated by river red gums which provide habitat for many species including the squirrel glider. Birds such as egrets, herons and cormorants use trees along the river to roost and feed while frogs benefit from shallow areas.

Mid-Goulburn River tributaries between Lake Eildon and Goulburn Weir are important for Macquarie perch habitat while freshwater catfish can be found in lagoons connected to the Goulburn River. The lower Goulburn River below the Goulburn Weir is a significant source of golden perch recruitment (when animals survive to settlement or maturity), and monitoring shows successful breeding in response to environmental water.

Social and economic values

The Goulburn River contributes a large proportion of water for the Murray–Darling Basin. As part of the Goulburn Broken catchment, it covers two percent of the area of the basin and contributes 11 percent of the water for use in the basin. The majority of this water is used by irrigated agriculture. The Goulburn River is popular for recreation, fishing and boating. Fishing in particular provides substantial economic and social benefits to the region and the river supplies water for towns and stock and domestic users. The river's floodplain also has many important Aboriginal cultural heritage sites such as scar trees, mounds, stone artefact scatters and middens. The Goulburn River continues to be a place of importance for Traditional Owners and their Nations.

Conditions mid-2016

The dry conditions of 2014–15 became even more severe in 2015–16. Only very small fluctuations in river level occurred from unregulated flows (natural streamflows that can't be captured in major reservoirs or storages), meaning environmental water deliveries provided the only significant higher flows and flow variability in the lower Goulburn River (reaches 4 and 5). Water released from Lake Eildon and extracted from the river at Goulburn Weir met or exceeded some environmental targets in the mid-Goulburn River (reaches 1, 2 and 3).

Environmental water was delivered downstream of Goulburn Weir through winter and spring to provide baseflows (low flows) which supported fish and waterbug habitat. One spring fresh (small pulses of water) and one autumn fresh were delivered to help plants on the banks recover, and some significant improvements in plant growth on the lower bank were observed. Some of the environmental water delivered down the Goulburn River was primarily targeted to meet environmental needs in Gunbower Forest and South Australia. No environmental water was released between November and mid-March due to the delivery of consumptive (mainly irrigation) water to the River Murray. Close collaboration between waterway and storage managers resulted in these flows also meeting environmental flow targets.

Monitoring found continued improvement of bank plants with an excellent response of mostly native plants establishing on the lower bank. A second spring fresh was not delivered in 2015–16 as a result of reduced water availability and consequently golden and silver perch breeding was not recorded. However, perch are a long-lived fish and breeding was achieved in the previous two years so this was a lower priority under drier conditions and lower water availability.

Fish surveys continued to record native species such as the Murray cod, Australian smelt, golden and silver perch, trout cod and Murray–Darling rainbowfish. The introduced European carp are also prevalent. Of note, while in past years perch breeding has been successful, recruitment (when animals survive to settlement or maturity) has not been found in the Goulburn River, with an absence of young fish (one to two years old). The reason for this is unclear, though there is a high possibility that the eggs/juvenile fish move into the River Murray. If wet conditions occur in 2016–17, a trial of a summer pulse is proposed to determine if increased flows at this time will attract perch into the Goulburn.

All environmental water deliveries are managed to protect damage to the river banks. This is done by adding variation to stable flows and carefully controlling the rate of rise and fall of freshes. Monitoring of bank condition is showing very positive results with some areas showing thin layers of sediment left on the banks from the delivery of environmental water. This material is supporting the germination and growth of new bank plants.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Goulburn River

Potential environmental watering1

Environmental objectives

Year-round baseflows (500 ML/day in reach 4 and/or 540 ML/day in reach 5)

  • Maximise habitat and movement opportunities for large- and small-bodied native fish
  • Provide conditions that support waterbug habitat and food resources including maintaining suitable water quality, encouraging the establishment of aquatic vegetation, submerging snags and encouraging planktonic production

Spring fresh (1 fresh of up to 15,000 ML/day with flows above 5,600 ML/day for 14 days in reach 4 and reach 5 in September–November)

  • Support establishment of flood-tolerant bank vegetation
  • Maintain macrophyte, waterbug and fish habitat by mobilising fine sediments, submerging snags and replenishing slackwater habitat
  • Initiate spawning and pre-spawning migration and support recruitment of golden perch

Winter fresh (1 fresh of up to 15,000 ML/day with flows above 6,600 ML/day for 14 days in reach 4 and reach 5 in June–August 2017)

  • Maintain macrophyte, waterbug and fish habitat by mobilising fine sediments, submerging snags and replenishing slackwater habitat

Summer/autumn fresh (1 fresh of up to 5,600 ML/day for 2 days in reach 4 and reach 5 in February–April)

  • Maintain macrophyte, waterbug and fish habitat by mobilising fine sediments, submerging snags and replenishing slackwater habitat
  • Support establishment of flood-tolerant bank vegetation

Spring/summer fresh (1 fresh of up to 15,000 ML/day for 2 days in reach 4 and reach 5 in November–December)

  • Initiate spawning and pre-spawning migrations and recruitment of golden perch
  • Maintain macrophyte, waterbug and fish habitat by mobilising fine sediments, submerging snags and replenishing slackwater habitat

Increased baseflows (830 ML/day in reach 4 and/or 940 ML/day in reach 5 year-round)

  • As for 500–540 ML/day baseflows, plus ...
  • Submerge additional snags for waterbug food and habitat
  • Maintain pool depths and sediment distribution
  • Provide area of slackwater habitat in spring/summer to support spring-spawned larvae and juvenile fish

Summer/autumn pulse (up to 5,000 ML/day in reach 4 and/or reach 5 for 10 days between January–March)

  • Flows for fish migration

1 Environmental water may be used to slow the recession of unregulated flows or operational releases to reduce damage to banks and vegetation from rapid drops in water levels. This also helps prevent waterbugs and fish from being stranded in small pools on river banks or benches following higher flows.

Scenario planning

Various triggers for action are applied as part of the adaptive management of environmental water in the Goulburn system. For example, the second of the two proposed spring freshes that target golden perch breeding may not be delivered if monitoring shows breeding was achieved during the first, longer-duration spring fresh.

The highest priority for environmental watering in 2016–17 will be providing year-round baseflows and the long-duration spring fresh and summer/autumn fresh. These provide improved habitat for animals in the river channel and support plants on the river banks and margins. Under drought or dry conditions the freshes are likely to be smaller due to less water being available. If better conditions occur, additional freshes and increased baseflows become achievable, targeting spawning and migration of golden and silver perch, waterbug and fish habitat and additional enhancement of bank plants.

Under drier scenarios, environmental water objectives focus on maintaining the health of the system. Under wetter scenarios, unregulated flows and water allocations are expected to increase, providing a greater opportunity to improve the health of the river as additional objectives can be achieved. Tier 2 actions are included as desirable objectives if more water becomes available.

In determining potential watering actions for 2016–17, consideration was given to critical carryover into 2017–18. Under a dry or below-average scenario, carryover is a priority to ensure baseflows (low flows) can be provided from July–September 2017. Under drought conditions the benefits of using all available water to maintain the health of the river are greater than keeping some for the next year. If average or wet conditions occur, the increase in water availability for 2017–18 would mean this carryover would not be essential.

Table 2 Potential environmental watering for the Goulburn River under a range of planning scenarios

Planning scenario

Drought

Dry

Below-average

Average-Wet

Expected river conditions

  • No unregulated flows
  • Unregulated flows expected to provide some baseflows between winter to mid-spring and likely winter-spring freshes
  • Unregulated flows expected to provide baseflows in winter to mid-spring and likely winter-spring freshes
  • Unregulated flows expected to provide high baseflows and multiple overbank flows events in winter/spring
  • Normal minimum passing flows at reach 5 of 400 ML/day from July–October and 350 ML/day from November–June

Expected availability of environmental water

  • 74,000 ML carryover
  • 15,000 ML VEWH
  • 58,000 ML CEWH
  • 8,000 ML Living Murray
  • 155,000 ML total
  • 74,000 ML carryover
  • 15,000 ML VEWH
  • 149,000 ML CEWH
  • 21,000 ML Living Murray
  • 259,000 ML total
  • 74,000 ML carryover
  • 15,000 ML VEWH
  • 276,000 ML CEWH
  • 39,000 ML Living Murray
  • 404,000 ML total
  • 74,000 ML carryover
  • 15,000 ML VEWH
  • 276,000 ML CEWH
  • 39,000 ML Living Murray
  • 404,000 ML total

Potential environmental watering – tier 1 (high priorities)

  • Year-round baseflows
  • Spring fresh (partial event)
  • Summer/autumn fresh (partial event)
  • Year-round baseflows
  • Spring fresh
  • Summer/autumn fresh (partial event)
  • Year-round baseflows
  • Spring fresh
  • Summer/autumn fresh
  • Increased baseflows (year-round)
  • Spring/summer fresh
  • Recession flow management
  • Year-round baseflows
  • Spring fresh
  • Summer/autumn fresh
  • Increased baseflows (year-round)
  • Spring/summer fresh
  • Summer/autumn pulse
  • Recession flow management
  • Winter 2017 fresh (partial-full event)

Potential environmental watering – tier 2 (additional priorities)

  • Increased baseflows (year-round)
  • Spring/summer fresh
  • Summer/autumn pulse
  • Recession flow management
  • Winter 2017 fresh
  • Increased baseflows (year-round)
  • Spring/summer fresh
  • Summer/autumn pulse
  • Recession flow management
  • Winter 2017 fresh
  • Summer/autumn pulse
  • Winter 2017 fresh
Winter 2017 fresh (full event)

Possible volume of environmental water required to achieve objectives1

  • 135,000 ML (tier 1)
  • 400,000 ML (tier 2)
  • 237,000 ML (tier 1)
  • 400,000 ML (tier 2)
  • 378,000 ML (tier 1)
  • 193,000 ML (tier 2)
  • 378,000 ML (tier 1)
  • 0–120,000 ML (tier 2)

Critical carryover into 2017–18

  • 0 ML
  • 23,000 ML
  • 23,000 ML
  • 0 ML

1 Environmental water requirements for tier 2 actions are additional to tier 1 requirements.

Risk management

In preparing its seasonal watering proposal, Goulburn Broken Catchment Management Authority considered and assessed risks and identified mitigating strategies relating to the implementation of environmental watering. Risks and mitigating actions are continually reassessed by program partners throughout the water year.

Engagement

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

In the Goulburn Broken region communities are involved in decisions about the Goulburn River and wetlands, Broken River and wetlands and the Murray River and wetlands. This happens through formal advisory groups: Environmental Water Advisory Groups focusing on rivers, a wetland advisory group and the Barmah Millewa Operations Advisory Group.

Who is engaged and how

Recreational users

Through formal advisory groups, recreational users provide local advice and raise opportunities for 'shared benefits' including whether the timing of environmental watering may align with key recreational events such as cod and duck opening. Recreational users are informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Goulburn-Murray Water directly engages with recreational user groups that use Goulburn-Murray Water water storages for recreation through planned consultations and meetings to discuss storage levels and potential impacts of environmental water releases from storages.

Environment groups

Through formal advisory groups, environment groups provide local knowledge, land management advice and advocate for the environment. They are also informed of environmental water deliveries and provide data that assists with reporting on the
outcomes of environmental watering.

Landholders/farmers

Through formal advisory groups, farmers and landholders (who often own land with river frontages) provide local knowledge and land management advice. They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Traditional Owners

Through the Goulburn Broken Catchment Management Authority Indigenous Facilitator, the Yorta Yorta Nation (responsible for managing some land and reserves in the region) is given the opportunity to provide input to seasonal watering proposals through annual briefings with the Catchment Management Authority.

There are Yorta Yorta representatives from the Goulburn Broken region who are members of the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Holder and the Murray Darling Basin Authority engage Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Councils

Through the wetland advisory group (due to their role as land managers for some wetlands), Councils provide local advice.
They also support local advertising during water delivery and share data for reporting.

Goulburn-Murray Water consults with the Greater Shepparton City Council and the Moira Shire Council regularly on water management, including on environmental water management.

General public

The Goulburn Broken Catchment Management Authority communicates through their website, media releases, advertisements in local papers, a column in Country News, in the Goulburn Broken Catchment Management Authority bi-monthly newsletter, social media, radio, community forums and partnered research.