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Three main storages are located on the Loddon River: Cairn Curran, Tullaroop and Laanecoorie reservoirs. Downstream of Laanecoorie Reservoir, river flows are regulated by the operation of the Bridgewater, Serpentine, Loddon and Kerang weirs.

Water for the environment can be delivered to the Loddon River from Cairn Curran or Tullaroop reservoirs or from
the Goulburn system via the Waranga Western Channel, which intersects with the Loddon River at Loddon Weir. Water is provided to Pyramid Creek through releases from Kow Swamp, which receives water diverted from the River Murray at Torrumbarry Weir. Water is diverted from the Loddon River to Serpentine Creek and to the Loddon Valley Irrigation Area to supply agriculture.

The highly regulated nature of the Loddon system provides both challenges and opportunities for effective management of water for the environment. The ability to manipulate the timing of releases at multiple locations provides opportunities to accomplish environmental outcomes at discrete locations. However, coordinating environmental flows and consumptive flows is difficult through the irrigation season, especially when irrigation demand is high. This can lead to constraints in the timing and delivery of water for the environment or higher-than-recommended flows upstream of Loddon Weir. The structures used for managing irrigation water form barriers in the waterway, restricting continuity and the ability to achieve outcomes for native fish and possibly platypus.

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 Loddon River

Fish icon
Increase populations of small and large-bodied native fish and opportunities for movement between habitats
Landscape icon
Maintain and enhance the channel form and features including deep pools and benches Maintain the condition of suitable substrate, to maintain ecosystem processes Engage floodrunners, distributary channels, anabranches and backwaters
Platypus icon
Increase the population and recruitment of resident platypus Maintain the rakali (water rat) population
Plant icon
Maintain the riparian and floodplain vegetation and facilitate the recruitment of woody and non- woody vegetation Maintain and increase the extent of in-stream vegetation Limit the encroachment of fringing vegetation into the stream channel
Insect icon
Maintain/increase the diversity and productivity of waterbugs and waterbug functional feeding groups, to drive productive and dynamic foodwebs
Water icon
Maintain water quality, to support aquatic animals and minimise the risk of blackwater events

Environmental values

The Loddon River system supports platypus, rakali (water rats) and several species of native fish. Streamside vegetation varies in condition depending on the recent water regime, the extent of clearing and historic and current land management practices. Those areas remaining relatively intact support a variety of woodland birds and other native animals. Important plant species across the system include cane grass, tangled lignum, black box and river red gum.

Although fish populations in the Loddon system are affected by the many barriers caused by weirs and reservoirs, a large range of species are still found through the catchment. Native fish are most abundant and diverse in the upper catchment. River blackfish are found in Serpentine Creek and rare Murray-Darling rainbow fish are found in the middle and lower sections of the Loddon River.

The highest-priority reach for environmental watering is from Loddon Weir to Kerang Weir. The reach does not carry irrigation water, and it relies heavily on environmental flows to maintain its environmental condition. Environmental flows to this reach aim to improve the condition of riparian vegetation, maintain water quality and increase the abundance and diversity of native fish. Environmental flows are delivered to the upper Loddon River, Tullaroop Creek and Serpentine Creek to maintain or increase populations of river blackfish and platypus.

Pyramid Creek and the lower Loddon River support large-bodied fish (such as golden perch, Murray cod and silver perch) and are important corridors for fish migration between the Loddon and Murray systems. Engineering works to provide fish passage at the Chute, Box Creek regulator, Kerang Weir, Fish Point Weir and Little Murray Weir on the Little Murray River in recent years have

been important in reopening these migration routes. The Arthur Rylah Institute has monitored fish movement and populations in Pyramid Creek and the lower Loddon River since 2017, and results have indicated that the combined Loddon-Pyramid flow is stimulating native fish movement through the fishways.

Conditions 2018

Rainfall in the Loddon catchment was much lower than average throughout most of 2018–19, although several storms in December meant rainfall for that month was above average. Natural streamflow and inflows to storages were very low throughout 2018–19, as most rainfall was absorbed by soils and did not generate much run-off. Despite the very dry conditions, there was adequate water available to deliver all planned flows for the Loddon River, Pyramid Creek and Serpentine Creek under a dry scenario, but the presence of blue-green algae in Loddon and Kerang weirs prevented delivery of freshes to the Loddon River in autumn.

While only one summer fresh could be delivered in the Loddon River, low flows were delivered throughout the year, meeting targets in the priority reach (reach 4). A fresh of up to 400 ML per day was delivered to reach 4 in spring, and it was timed to coincide with an environmental flow in Pyramid Creek to cue native fish movement.

Water for the environment was used to deliver two summer/autumn freshes and one winter/spring fresh to Serpentine Creek in 2018–19. A minimum operational flow of 7 ML per day was provided at other times. The summer freshes helped alleviate low-dissolved-oxygen levels in reach S1 during prolonged hot weather in January 2019. Environmental flows delivered to Serpentine Creek subsequently flowed through to Nine Mile Creek, where they supported vegetation and aquatic animals.

Two environmental flows were provided to Pyramid Creek during 2018–19, to support North Central CMA’s Native Fish Recovery Plan – Gunbower and Lower Loddon. The first was delivered in spring and involved coordinated releases through Pyramid Creek and reach 4 of the Loddon River, to attract fish from the lower Loddon and River Murray to move through Kerang Weir and the Box Creek regulator fishway at Kow Swamp. The second environmental flow to Pyramid Creek was delivered at the end of the irrigation season in mid-May to prevent fish becoming stranded when the irrigation system was drained. Target environmental flows in Pyramid Creek could not be achieved without the cooperation and expertise of the storage manager, Goulburn-Murray Water.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Loddon River system

Potential environmental watering action

Functional watering objective

Environmental objective

Loddon River (reach 1)

Summer/autumn fresh (one to four freshes of 35–80 ML/day for one to three days during December to May)

  • Flush fine sediment from hard surfaces
  • Increase the water level, to promote the growth of fringing emergent macrophytes
  • Increase connectivity to promote the local movement of adult fish and encourage juvenile fish and platypus dispersal in autumn
  • Wet submerged wood to flush old biofilms and promote new biofilm growth
Fish iconMountain iconsPlatypus iconPlant icon

Spring fresh (one fresh of 400–700 ML/day for four to five days during September to October)

  • Redistribute fine sediment on bars and benches
  • Flush accumulated leaf litter, to increase productivity and reduce the risk of hypoxic blackwater event in summer
  • Increase the wetted area, to promote the recruitment and maintenance of riparian vegetation on the banks and benches
  • Stimulate the movement of Murray cod, to encourage breeding
Fish iconMountain iconsPlant iconWater drop icon

Tullaroop Creek (reach 2)

Summer/autumn fresh (one to four freshes of 30–40 ML/day for one to three days during December to May)

  • Flush fine sediment from hard surfaces
  • Increase the water level, to promote the growth of fringing emergent macrophytes
  • Increase connectivity, to promote the local movement of adult fish and encourage juvenile fish and platypus dispersal in autumn
  • Wet submerged wood to flush old biofilms and promote new biofilm growth

Fish iconMountain iconsPlatypus iconPlant iconInsect iconWater drop icon

Spring fresh (one fresh of 200–400 ML/day for one to five days during September to October)

  • Redistribute fine sediment on bars and benches
  • Flush accumulated leaf litter, to increase productivity and reduce the risk of hypoxic blackwater event in summer
  • Increase the wetted area, to promote the recruitment and maintenance of riparian vegetation on the banks and benches
  • Stimulate the movement of Murray cod, to encourage breeding
Fish iconMountain iconsPlant iconWater drop icon

Loddon River (reach 4)

Summer/autumn fresh (one to three freshes of 50–100 ML/day for three to four days during December to May)

  • Flush fine sediment from hard surfaces
  • Increase the water level, to promote the growth of fringing emergent macrophytes
  • Increase connectivity, to promote the local movement of fish and platypus including juvenile dispersal in autumn
Fish iconMountain iconsPlatypus iconPlant icon

Winter/spring high flow (one high flow of 450–750 ML/day for six to 10 days during August to November)1

  • Provide flow through flood runners
  • Scour accumulated sediment from pools
  • Flush accumulated organic matter from the bank and benches, to increase productivity and reduce the risk of hypoxic blackwater event in summer
  • Increase the wetted area, to promote the recruitment and growth of riparian and emergent vegetation
  • Stimulate native fish movement and breeding
Fish iconMountain iconsPlant iconInsect iconWater drop icon

Summer/autumn low flow (25–50 ML/day during December to May)

  • Maintain an adequate depth in pools for aquatic plants and to provide habitat for waterbugs, fish and rakali (water rats)
  • Provide continuous flow through the reach, to maintain water quality
  • Maintain connecting flows to support in-stream and fringing non- woody vegetation
Fish iconPlatypus iconPlant iconInsect iconWater drop icon

Winter/spring low flow (50–100 ML/day during June to November)

  • Increase the water depth for fish, platypus and rakali (water rats) dispersal and to provide foraging habitat
  • Prevent silt and fine sediment settling on submerged wood and other hard surfaces
  • Prevent the growth of terrestrial plants in the river channel
Fish iconMountain icons Platypus iconPlant iconInsect iconWater drop icon

Autumn high flow (up to one high flow of 400 ML/day for 6–10 days during March to May)

  • Trigger and facilitate the upstream movement of golden perch, silver perch and Murray cod older than one year

Fish icon

Serpentine Creek (reach S1)2

Winter/spring fresh (one fresh of 40–150 ML/day for two days during August to November)

  • Maintain the channel form and scour pools
  • Provide connectivity for fish and waterbugs to access different habitat areas
  • Transport organic matter that has accumulated in the channel
  • Provide a cue for adult platypus to construct burrows above the higher water level
Fish iconMountain iconsPlatypus iconInsect iconWater drop icon

Summer/autumn fresh (one to three freshes of 30–40 ML/day for one to three days during December to May)

  • Maintain the channel form by engaging benches
  • Flush fine sediment and scour biofilms, to replenish the food supply
  • Transport organic matter that has accumulated in the channel
  • Provide flow variability to maintain the diversity of fringing vegetation
  • Provide a sufficient depth of water and variability of flow to maintain microbial biofilms
Mountain iconsPlant iconInsect iconWater drop icon

Summer/autumn low flow (10–20 ML/day during December to May)

  • Prevent notching of riverbanks by providing flow variability
  • Provide connectivity between pools to allow the dispersal of small-to- medium-bodied native fish
  • Wet exposed roots, leaf packs and woody debris, to provide habitat for aquatic animals
  • Provide sufficient flow to maintain water quality by re-oxygenating pools and preventing stagnation
  • Maintain foraging habitat for platypus
  • Maintain the wetted area to support in-stream aquatic vegetation (e.g. water ribbons, eel weed and milfoil)
Fish iconMountain icons Platypus iconPlant iconInsect iconWater drop icon

Winter/spring low flow (20–30 ML/day during June to November)

  • Maintain spawning habitat for native fish
  • Wet exposed roots, woody debris, emergent vegetation and leaf packs, to provide habitat for aquatic animals
  • Maintain water quality by preventing stagnation
  • Provide flow variability, to maintain diversity of fringing vegetation
  • Provide a sufficient depth of water and variability of flow to maintain microbial biofilms
Fish iconPlant iconInsect iconWater drop icon

Pyramid Creek and Loddon River (reach 5)

Spring high flow (one high flow of 700–900 ML/day for 10 days during September to October)

  • Trigger the migration, spawning and recruitment of native fish species including Murray cod
  • Maintain connectivity between habitats and improve water quality
Fish iconWater drop icon

Autumn/winter low flow (90–200 ML/day during May to August)

  • Maintain connectivity between pools and provide habitat for fish and waterbugs outside of the irrigation season
  • Improve water quality by reducing salinity levels
  • Enhance the wetted area to maintain and promote the growth of fringing emergent (non-woody) vegetation along the lower banks of the channel
  • Redistribute fine sediment on benches and bars
Fish iconPlant iconInsect iconWater drop icon

Autumn high flow (up to one high flow of 700–900 ML/day for 10 days during March to May)

  • Trigger the migration, spawning and recruitment of native fish species including Murray cod
  • Facilitate the upstream movement of golden perch, silver perch and Murray cod older than one year
  • Maintain connectivity between habitats and improve water quality
  • Facilitate platypus dispersal
Fish iconPlatypus icon Water drop icon

1 Due to potential inundation of private land, environmental flows above 450 ML per day in reach 4 will not be provided without agreement of potentially affected landholders.

2 Flows in Serpentine Creek will be allowed to either return to the Loddon River via the channel system or continue down Pennyroyal Creek, Bannacher Creek and Nine Mile Creek with the agreement of landholders.

Engagement

Table 2 shows the partners and stakeholder organisations with which North Central CMA engaged when preparing their seasonal watering proposals.

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 North Central Regional Catchment Strategy and North Central  Waterway Strategy.

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

Partner and stakeholder engagement
  • Individual Landholders
  • Commonwealth Environmental Water Office
  • Goulburn- Murray Water
  • Victorian Environmental Water Holder
  • Department of Environment, Land, Water and Planning
  • Field and Game Australia
  • VRFish
  • Barapa Barapa Traditional Owners
  • Dja Dja Wurrung Clans Aboriginal Corporation
  • Wamba Wemba Traditional Owners