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The Glenelg River rises in the Grampians and flows west through Harrow and then south to Casterton and Dartmoor for over 500 km, making it one of the longest rivers in Victoria. A short stretch of the estuary winds through South Australia before returning to Victoria and flowing into the sea at Nelson.

The Glenelg River continues to be an important place for Traditional Owners and their Nations. The Registered Aboriginal Parties (RAPs) in the Glenelg River catchment are the Gunditj Mirring Traditional Owner Aboriginal Corporation and the Barengi Gadjin Land Council. Representatives from both RAPs were engaged during the preparation of the Glenelg system seasonal watering proposal.

Storage manager
Environmental water holder

System map

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

Plant icon
Promote in-stream and riverside plants to flower, set seed and germinateMaintain and increase the health of in-stream and riparian vegetation (such as river red gums and Wimmera River bottlebrush)
Protect and increase populations of native fishCue fish movement and spawning to increase the recruitment of species such as the short-finned eel, black bream, estuary perch and tupong
Insect icon
Maintain a wide range and large number of waterbugs to provide energy, break down organic matter and support the river’s food chain
Platypus icon
Maintain and increase the resident platypus population by providing places to rest, breed and feed, as well as opportunities for juveniles to disperse to the lower sections of the river
Move built-up sand on the river bed to provide healthy habitat pools for native fish, platypus, the critically endangered Glenelg freshwater mussel and the endangered Glenelg spiny crayfish
Water icon
Maintain water quality for fish, waterbugs, aquatic vegetation and other water-dependent animals

Environmental values

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

The Glenelg River supports a variety of riparian vegetation communities including the endangered Wimmera bottlebrush. Riparian and floodplain vegetation is comprised of river red gum woodlands with paperbark, bottlebrush and tea tree understorey.

Social and economic values

The Glenelg system is highly valued by recreational anglers and several fishing competitions are held on the river throughout the year along with high profile events such as an Australian Bream Tournament and the Victorian Fisheries Authority's annual 'great perch search', where volunteer anglers catch broodfish perch. Other recreational activities including walking, sightseeing boat cruises, canoeing, birdwatching and camping are popular along parts of the river. Many landholders rely on the Glenelg River for stock water, and they use the productive floodplains for grazing. The river provides tourism opportunities and supports businesses in Balmoral, Harrow, Casterton, Dartmoor and Nelson, among other towns.

Conditions 2018

Average rainfall during winter 2017 contributed to high natural flows in the Glenelg catchment. The high flows met many of the environmental flow objectives for winter and spring, and it eliminated the need for managed environmental flow releases. Passing flows were also suspended at various times during winter and spring to reduce the flood risk to communities downstream of Rocklands Reservoir. Water accumulated as a result of the suspended passing flows was used to help meet environmental objectives in summer.

The high natural flows during winter/spring and the provision of water for the environment during the summer/ autumn period maintained connectivity from Rocklands Reservoir to the estuary at Nelson throughout 2017–18. Seasonal fluctuations in flows and water levels throughout the year provided opportunities for aquatic plants and animals to disperse between river reaches and to also access a variety of habitats throughout the system. The flows also supported the health of riparian vegetation and the transfer of nutrients and debris from the riverbanks into the river channel. Continuous low flows maintained the quality and quantity of water in riffle-pool habitats. Occasional freshes reduced salinity and water temperature and increased dissolved oxygen concentrations in deeper pools along the river system.

The natural and managed flows in the Glenelg River during 2017–18 provided habitat for native fish and opportunities for fish dispersal, migration and spawning. Young-of-year tupong and estuary perch were recorded more than 40 km upstream of the estuary in summer 2017–18. Strong
migration of these fish species from the estuary corresponds with managed releases of water for the environment, which trigger migration and facilitate movement across habitats that are impassable at lower flows.

Allocations to the environment reached 81 percent in September 2017, based on water reserves from the wet 2016–17 season and good inflows into storages during early winter 2017. Conditions turned to dry during spring, with below-average rainfall and no inflow to storages between November 2017 and April 2018. As a result, there were no additional allocations to the environment after September 2017. Accumulated passing flows were used to meet environmental demands between late spring and mid-January 2018. Water allocated to the environmental entitlement was used to meet demand after that.

In November 2017, the first-ever release of water for the environment was delivered to reach 0 from Moora Moora Reservoir. The release aimed to improve understanding of water movement in the reach and how water can be delivered from the reservoir. Temporary gauges installed in reach 0 showed a significant rise of the river level following the release, but due to a significant rainfall event the full extent of the flow could not be measured accurately. Despite the measurement uncertainty, the trial release improved understanding of the potential for releases of water for the environment to support the important environmental values in reach 0 in the future.

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)

  • Maintain or increase the abundance and variety of waterbugs
  • Scour sand from pools to increase the quality and quantity of fish habitat
  • Maintain the condition of emergent vegetation on the lower banks
  • Flush pools to improve water quality and lower temperatures to improve habitat for Glenelg spiny crayfish, waterbugs and fish

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 low flows targeting reach 1a (10 ML/day or natural in December–May)1

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

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

Summer/autumn low flows 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 the condition of emergent vegetation and to maintain habitat diversity
  • Provide adequate depth for fish passage and cue fish movement
  • Support platypus habitat and breeding including triggers for burrow selection
  • Scour sand from pools to improve the quality of fish habitat
  • Maintain or increase vegetation diversity in the river and on channel benches

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

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

  • Maintain water quality for fish, waterbugs and aquatic vegetation
  • Maintain shallow-water habitat for fish, waterbugs and platypus

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

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

Trial release to reach 0 (up to 50 ML/day over a 4–5 day period)
  • Develop an operational understanding of our ability to deliver environmental flows to support values in this reach including the capacity of infrastructure, metering and safety considerations

1 Cease-to-flow events occur naturally in the Glenelg system and may be actively managed with deliveries of water for the environment to reduce stress on environmental values. 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. Cease-to-flow events ideally should be followed with a fresh event.

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 they can only be achieved through natural events.

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

Risk management

In preparing its seasonal watering proposal, Glenelg Hopkins CMA considered and assessed the risks of environmental watering and identified mitigation strategies. Program partners continually reassess risks and mitigation actions throughout the water year.


Table 2 shows the partners, stakeholder organisations and individuals with which Glenelg Hopkins CMA engaged when preparing the Glenelg system seasonal watering proposal.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the Glenelg Hopkins Regional Catchment Management Strategy and Glenelg Hopkins Waterway Strategy for further details.

Table 2 Partners and stakeholders engaged in developing the Glenelg system seasonal watering proposal

Partner and stakeholder engagement
  • Aboriginal groups (Gunditj Mirring Traditional Owner Corporation and Barengi Gadjin Land Council) 
  • Community members and landholders 
  • Department of Environment, Land, Water and Planning 
  • Environment groups: Glenelg River User Group and Friends of the Glenelg River 
  • Fisheries Victoria 
  • Glenelg Hopkins CMA Advisory Group including representatives of stakeholder groups and landholders in the region 
  • GWMWater 
  • Local tourism and sand extraction businesses and community service organisations based in Balmoral, Coleraine, Winnap, Nelson and the western Grampians 
  • Parks Victoria 
  • Recreational groups: Balmoral Angling Club, Casterton Angling Society, Dartmoor Angling Club, VRFish, Fishcare Victoria, the South West Fishing Report, individual anglers 
  • Victorian Environmental Water Holder 
  • Wimmera CMA