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The Glenelg River supports a wide range of flow-dependent environmental values including rare and threatened plants and animals. Its diversity results from its range of landforms and climate conditions and its connection with the estuary.

The Glenelg River is an integral part of the Wimmera–Mallee headworks system, which supplies towns and properties across the Western Region. The river is regulated at Moora Moora Reservoir and Rocklands Reservoir. Water is also diverted from the Glenelg catchment to the Wimmera catchment by the Moora Moora channel and the Rocklands–Toolondo–Taylors channel and at three weirs on the upper Wannon River. Environmental water is actively managed in the main stem of the Glenelg River below Rocklands Reservoir with passing flows rules in place for the upper Wannon River diversions.

Due to their high environmental value, the priority river reaches are from the Rocklands Reservoir to 5-Mile Outlet (reach 1a), 5-Mile Outlet to the confluence with the Chetwynd River (reach 1b) and from the Chetwynd River to the Wannon River (reach 2). Environmental water in the Glenelg system is released from Rocklands Reservoir for reach 1a via the reservoir wall outlet and for reach 1b via the 5-Mile and 12-Mile outlets, with through-flows delivering water to reach 2. The Glenelg River reach 3 and estuary also benefit from environmental water releases.

Although not managed for environmental needs, the Glenelg River above Rocklands Reservoir (reach 0) runs mostly through the Grampians National Park and retains significant environmental values. Further work is being undertaken to confirm the flow requirements of this reach. Work is also being undertaken to better understand the role that environmental releases from Rocklands Reservoir play in the health of the Glenelg River estuary (which is listed as a heritage river reach and has been nominated for listing under the Ramsar Convention).

Storage manager
Environmental water holder

System map

Glenelg 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 Glenelg system

Insect icon
Provide variable flows during low-flow season to support waterbugs, diverse habitats and water quality
Habitat icon
Facilitate localised scouring of sand for fish habitat
Plant icon
Maintain condition of emergent vegetation by wetting lower banks
Water icon
Flush pools to prevent water quality decline during low flows

Environmental values

The lower section of the Glenelg River is recognised as one of Australia's 15 national biodiversity hotspots due to the high-value aquatic life it supports, including the endangered Glenelg freshwater mussel and Glenelg spiny crayfish. It is also home to platypus and important native fish including river blackfish, estuary perch and pygmy perch, some of which migrate long distances upstream from the Glenelg River estuary to complete their lifecycles. Frasers Swamp is another important feature of the upper Glenelg system, supporting a healthy growling grass frog population.

The Glenelg River supports a variety of riparian plants including the endangered Wimmera bottlebrush. Riparian and floodplain plants are comprised of river red gums with paperbark and tea tree understorey.

Social and economic values

The Glenelg system is valued for fishing and several fishing competitions are held on the river throughout the year. Other recreational activities are popular along the river including walking, sightseeing, boat cruises, canoeing, bird watching and camping. Many landholders rely on the Glenelg River for stock water and use the productive floodplains for grazing. The river also provides tourism opportunities and supports businesses within townships such as Harrow, Casterton, Dartmoor and Nelson. The waterways in the Glenelg system are places of importance for Traditional Owners and their Nations in the region.

Conditions mid-2016

The Glenelg region was extremely dry in 2015–16. Low rainfall and inflows meant water allocations were only 16 percent and passing flows (water released from reservoirs to operate river and distribution systems, and maintain environmental values and other community benefits) from Rocklands Reservoir were severely reduced. Managing environmental water focused on maintaining water quality at key locations and reducing risks to plants and animals from the prolonged dry conditions.

Environmental water carried over from 2014–15 was critical to support flows in 2015–16. Along with low passing flows, low environmental water availability meant that no winter or spring watering was possible. In response to deteriorating water quality, environmental water was released to the Glenelg River in late October 2015, with two subsequent freshes (small pulses of water) released in December and February.

Water quality was improved as a result of all three freshes. Only a limited length of river could be watered as the losses for all deliveries were very high due to the dry conditions. Releases directly downstream of Rocklands Reservoir only reached Balmoral and releases from the 5-Mile and 12-Mile outlets reached Dergholm at much reduced rates compared to a wetter year. The river effectively ceased to flow at Casterton from November with environmental water releases only temporarily connecting discreet refuge pools to boost water quality.

Water quality was monitored at key sites in reaches 1b and 2 to inform and monitor the impact of environmental water releases. Although results demonstrated that each delivery did improve water quality, salinity steadily increased through the year.

Fish moved to refuge pools as the river ceased to flow and the river became a series of disconnected pools. A priority objective, given the low water availability in 2015–16, was to avoid critical losses of native fish. Fish abundance remained high during fish surveys in early 2016 with diversity at sampling sites reflecting previous sampling.

Plants in and along the Glenelg River have been especially impacted by prolonged cease-to-flow conditions with key habitat areas drying out and increased grazing pressure in riparian areas through 2015–16.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Glenelg system

Potential environmental watering

Environmental objectives

Summer/autumn freshes targeting reach 1a (2 freshes of 60 ML/day for 2–3 days each in December–May)

  • Provide variable flows during low-flow season to support waterbugs, diverse habitats and water quality
  • Facilitate localised scouring of sand for fish habitat
  • Maintain condition of emergent vegetation by wetting lower banks
  • Flush pools to prevent water quality decline during low flows

Summer/autumn freshes targeting reaches 1b (2 freshes of 100 ML/day for 2–3 days each in December–May)

Summer/autumn freshes targeting reach 2 (2 freshes of 150 ML/day for 2–3 days each in December–May)

Summer/autumn baseflows targeting reach 1a (10 ML/day or natural in December–May)1

  • Protect against rapid water quality decline over low-flow period
  • Maintain edge habitats, pools and shallow water habitat availability for fish, waterbugs and platypus
  • Maintain a near-permanent inundated stream channel to prevent excessive in-stream terrestrial species growth and promote in-stream vegetation

Summer/autumn baseflows targeting reach 1b (15 ML/day or natural in December–May)1

Summer/autumn baseflows targeting reach 2 (25 ML/day or natural in December–May)1

Winter/spring freshes targeting reach 1b (1–5 freshes of 250 ML/day for 1–5 days in June–November)2

  • Wet benches to improve condition of emergent vegetation and maintain habitat diversity
  • Increase the baseflow water depth and connectivity to provide stimulus and opportunity for fish movement
  • Facilitate localised scouring of sand for fish habitat
  • Maintain pools and inundate benches to improve in-stream habitat and vegetation diversity

Winter/spring freshes targeting reach 2 (1–5 freshes of 300 ML/day for 1–5 days in June–November)

Winter/spring baseflows targeting reach 1 a (60 ML/day or natural in June–November)1, 3

  • Provide desirable water quality conditions for fish, waterbugs and aquatic vegetation
  • Maintain seasonality of flows and improve habitat diversity by increasing wetted area from summer period
  • Maintain shallow water habitat availability for fish and waterbugs and facilitate annual dispersal of juvenile platypus

Winter/spring baseflows targeting reach 1b (100 ML or natural per day in June–November)1, 3

Winter/spring baseflows targeting reach 2 (160 ML/day or natural in June–November)1, 3

1 Cease-to-flow events occur naturally in the Glenelg system and may be actively managed. In the most recent flows study, the recommendation is that cease-to-flow events should occur as infrequently as possible and not exceed the duration of events that might have occurred naturally, to reduce stress on environmental values. Cease-to-flow events should be followed with a fresh.

2 Winter/spring freshes in reach 1a are important to the health of the Glenelg River but due to operational constraints and potential flooding risks achievement relies solely on natural events.

3 Passing flows provided under the environmental entitlement generally provide winter/spring baseflows. However, if passing flows are reduced, managed environmental water releases may be required to supplement them or to ensure appropriate rates of rise and fall and provide appropriate conditions in fresh events.

Scenario planning

It is unlikely that there will be sufficient environmental water available to deliver all potential environmental watering actions in 2016–17. 

Tier 1 watering actions are those that can be delivered with the available water. Tier 2 watering actions include the water required to meet the remaining actions recommended by the scientific flow study under different climatic scenarios. While the actions are similar in each scenario, the magnitude, duration and/or frequency differ between scenarios: therefore the volume required under each scenario also differs.

Due to the prolonged dry conditions in the region and associated low flows, water quality is likely to remain poor and pose a risk to aquatic species. Environmental water will help to minimise but not completely mitigate these impacts. As the dry conditions continue, the condition of the plants and animals in the system is likely to deteriorate, and the ability of the plants and animals to survive and recover will be reduced.

Under most scenarios, there will likely be periods of cease-to-flow in summer. Where possible, the duration of these cease-to-flow periods will be carefully managed and monitored to minimise adverse impacts and inform environmental water releases. The priority is to protect water quality and refuge pools to ensure habitat is available for native fish and other animals (such as platypus) in the warmer months (when the risks are highest). Winter watering will only be possible if there are significant inflows and allocations in the early part of the water year.

If wet conditions eventuate, the priority will be increasing the magnitude, frequency and duration of planned watering actions and providing or supplementing flows in the winter/spring period. Natural river flows and passing flows are also likely to contribute to achieving these objectives. Reserving water for carry over into the 2017–18 water year will also be a priority if wetter conditions eventuate.

Table 2 Potential environmental watering for the Glenelg system under a range of planning scenarios

Planning scenario

Extreme drought

Drought

Dry

Average

Wet

Expected availability of environmental water1

  • 6,334 ML carryover
  • 5,000 ML VEWH
  •  0 ML CEWH2
  • 11,334 ML total3
  • 6,334 ML carryover
  • 7,839 ML VEWH
  •  0 ML CEWH2
  • 14,173 ML total3
  • 6,334 ML carryover
  • 17,979 ML VEWH
  •  0 ML CEWH2
  •   24,313 ML total3
  • 6,334 ML carryover
  • 30,553 ML VEWH
  •  0 ML CEWH2
  •  36,887 ML total3
  • 6,334 ML carryover
  • 45,560 ML VEWH
  • 0 ML CEWH2
  • 51,894 ML total3

Expected river conditions

  • No passing, compensation or unregulated flows
  • No passing, compensation or unregulated flows
  • Restricted passing and compensation flows and no unregulated flows
  • Some passing, compensation and unregulated flows, particularly in winter/spring
  • Some passing, compensation and unregulated flows

Potential environmental watering – tier 1 (highest priorities)4

  • Summer/autumn freshes reach 1b
  • Summer/autumn freshes reach 1a
  • Summer/autumn baseflows reach 1b
  • Summer/autumn freshes reach 2
  • Winter/spring freshes reach 1b
  • Summer/autumn freshes reach 1a
  • Winter/spring freshes reach 1b
  • Summer/autumn freshes reach 2
  • Spring/summer
    /autumn baseflows reach 1b
  • Winter/spring baseflows reach 2
  • Summer/autumn baseflows reach 2
  • Winter/spring baseflows reach 1a
  • Winter/spring baseflows reach 1b
  • Winter/spring baseflows reach 2
  • Summer/autumn freshes reach 1b
  • Summer/autumn freshes reach 1a
  • Winter/spring freshes reach 1b
  • Summer/autumn freshes reach 2
  • Summer/autumn baseflows reach 1b
  • Summer/autumn baseflows reach 1a
  • Summer/autumn baseflows reach 2
  • Summer/autumn freshes reach 1b
  • Summer/autumn freshes reach 1a
  • Winter/spring freshes reach 1b
  • Summer/autumn freshes reach 2
  • Summer/autumn baseflows reach 1b
  • Summer/autumn baseflows reach 1a
  • Summer/autumn baseflows reach 2
  • Winter/spring baseflows reach 1a, 1b and 2

Potential environmental watering – tier 2 (additional priorities)

  • Summer/autumn baseflows reach 1b
  • Summer/autumn baseflows reach 1a
  • Summer/autumn baseflows reach 2
  • Winter/spring baseflows reach 1a
  • Winter/spring baseflows reach 1b
  • Winter/spring freshes reach 2
  • Winter/spring baseflows reach 2
  • Summer/autumn baseflows reach 1a
  • Summer/autumn baseflows reach 1b
  • Winter/spring freshes reach 1b
  • Summer/autumn baseflows reach 2
  • Winter/spring baseflows reach 1a
  • Winter/spring baseflows reach 1b
  • Winter/spring freshes reach 2
  • Winter/spring baseflows reach 2
  • Spring/summer/
    autumn baseflows reach 1b
  • Summer/autumn baseflows reach 1a
  • Winter/spring baseflows reach 1b
  • Winter/spring baseflows reach 1a
  • Summer/autumn baseflows reach 2
  • Winter/spring freshes reach 2
  • Winter/spring baseflows reach
  • Summer/autumn baseflows reach 2
  • Winter/spring baseflows reach 1a
  • Winter/spring baseflows reach 1b
Winter/spring baseflows reach 2

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Possible volume of environmental water required to achieve objectives5

  • 5,600 ML (tier 1)
  • 33,700 ML (tier 2)
  • 7,087 ML (tier 1)
  • 47,793 ML (tier 2)
  • 12,157 ML (tier 1)
  • 39,973 ML (tier 2)
  • 18,443 ML (tier 1)
  • 17,967 ML (tier 2)
23,450 ML (tier 1)

1 Environmental water in the Wimmera–Glenelg system is shared between the Glenelg and Wimmera systems. The volumes specified show the likely availability across the shared systems and include 5,000 ML of allocation expected to be available through trade in 2016–17.

2 Commonwealth environmental water is only available for use in the Wimmera system.

3 This volume is a forecast of the total water likely to be available under the VEWH entitlement in 2016–17, including carryover water and the forecast allocation for the complete water year. The forecast opening allocation for each climate scenario is 0 ML under all scenarios, meaning the only water available is likely to be the carryover of about 6,300 ML at the start of the water year.

4 As the entitlement is shared between the Wimmera and Glenelg catchments, planning for tier 1 for each CMA has included a simplifying assumption that half of the expected allocations will be available to each CMA. A prioritisation process will be undertaken in consultation with the Wimmera and Glenelg Hopkins CMAs to determine the potential watering actions that will be undertaken in each system in the 2016–17 year.

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

Risk management

In preparing its seasonal watering proposal, Glenelg Hopkins Catchment Management Authority considered and assessed risks and identified mitigating strategies relating to implementing 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.

Communities in the Glenelg Hopkins region are involved in decisions about the Glenelg river system through the Glenelg Hopkins Catchment Management Authority advisory group.

Who is engaged and how

Recreational users

The Glenelg Hopkins Catchment Management Authority engages the Glenelg River Users Group directly through the Catchment Management Authority advisory group. The Catchment Management Authority also notifies the Glenelg River Users Group about planned environmental water deliveries and outcomes from environmental watering through email, SMS and social media.

The Catchment Management Authority engages local angling clubs on environmental watering on an as-needs basis.

Environment groups

The Catchment Management Authority notifies groups that advocate for the environment (primarily the Nelson Coastcare group, and also the Glenelg River Users Group) about planned environmental water deliveries and the beneficial environmental outcomes from environmental watering.

Landholders/farmers

Landholders and industry groups (grains, beef, dairy, lamb and wool) sit on the Catchment Management Authority advisory group. Landholders are notified about planned environmental water deliveries (timing and duration) via SMS.

Landholders are also engaged through informal one-on-one meetings and are invited to fish survey days to assist in reporting outcomes of environmental watering.

Sand extractors in the Glenelg are informed of planned environmental water deliveries (timing and duration) via SMS and email (as environmental watering can impact on their business).

Traditional Owners

Gunditjmara and Eastern Maar peoples (separate, but related groups of native title holders in this region) are engaged via the Catchment Management Authority advisory group on long term and annual environmental watering priorities and objectives.

The Gunditj Mirring Traditional Owners Aboriginal Corporation and the Barengi Gadjin Land Council are both currently working with the Catchment Management Authority to undertake a water values and uses scoping project in the Glenelg river system, which will explore Traditional Owner management interests and aspirations in the Glenelg river system.

Councils

Consultation with the Southern Grampians Shire Council is issues focussed. The Southern Grampians Shire Council aim to protect the interests of the local community when it comes to environmental watering.

General public

The Catchment Management Authority engages and communicates with the general public about environmental watering via SMS, their website, and media releases.