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Covering 19,450 ha, it is bounded by the River Murray to the north and Gunbower Creek to the south. It is an internationally significant site under the Ramsar Convention and forms part of the Living Murray Gunbower-Koondrook- Perricoota forests icon site. River regulation and water extraction from the River Murray and Gunbower Creek has reduced the frequency, duration and magnitude of flood events in Gunbower Forest. This has affected the extent and condition of floodplain habitats and the health of plant and animal communities (such as river red gum and black box communities, native fish, birds, platypus, frogs and turtles) that depend on those habitats.

Gunbower Creek is managed primarily as an irrigation carrier and supplies the Torrumbarry Irrigation Area from the River Murray. Daily variations in water levels in the creek through spring, summer and autumn are much higher now than under natural conditions, due to changing irrigation demand. Frequent or rapid fluctuations in water levels can greatly affect native fish populations and other ecological processes. Water for the environment is used to reduce water level fluctuations by filling the gaps in flows caused by irrigation demand within the creek. This action supports native fish migration and breeding and promotes other ecological processes while maintaining water delivery for irrigation needs.

The Living Murray structural works program in the middle and lower forest was completed in 2013. The works allow up to 4,500 ha of the wetlands and floodplain to be watered with considerably less water than would be required if the new watering infrastructure was not in place. The works enable efficient watering through Gunbower Creek and the forest to maintain wetland and floodplain condition, and they provide a link between the creek, forest floodplain and the River Murray. Frequent connections between the river and floodplain habitats allow biota to move between habitats, and they also support critical ecosystem functions (such as carbon exchange).

System map

2018-Northern-Gunbower-map

Environmental watering objectives in Gunbower Creek and Forest

Maintain and increase populations of large and small-bodied native fish (such as Murray cod)
Increase the population of frogs in the forest by providing feeding and breeding habitat
Connected icon
Maintain connections between the River Murray, Gunbower Forest floodplain, wetlands and floodrunners and Gunbower Creek
Maintain the population of turtles
Maintain the health and increase the abundance of native vegetation in priority permanent and semi-permanent wetlands

Improve the health of river red gums, black box and grey box communities
Provide feeding, breeding and refuge habitat for waterbirds including colonial nesting species, such as egrets, cormorants and herons
Water icon
Maintain and improve water quality in Gunbower Creek

Environmental values

Gunbower Forest contains many important environmental values including rare and diverse wetland habitats, vulnerable and endangered plants (such as river swamp wallaby-grass and wavy marshwort) and animals, and large areas of remnant vegetation communities (such as river red gum forest). The forest provides habitat for many bird and small-bodied native fish species, and it is known to support internationally recognised migratory waterbirds, such as eastern great and intermediate egrets.

Gunbower Creek provides important habitat for native fish (such as Murray cod, golden perch and freshwater catfish). It is a valuable refuge for native fish, and it provides a source of fish to recolonise surrounding waterways.

Recent conditions

Following two very hot and dry summers, 51.8 GL of water for the environment was delivered to Gunbower Forest from mid-June 2018 to the end of October 2018. The water inundated about 4,500 ha of the forest floodplain, floodrunners and wetlands, which included 25 percent (3,233 ha) of all river red gum areas and 87 percent (1,199 ha) of all wetlands within Gunbower Forest. The inundation supported the flood-dependent understorey and continued the long-term recovery of wetland plant communities from the Millennium Drought.

Flows into the forest improved the health of river red gum forest habitats. Understorey communities within inundated areas had greater coverage of aquatic, amphibious and mudflat plant species compared to areas that remained dry. Responses in wetlands were more varied, which may be partly due to the presence of large carp. Wetlands with small populations of adult carp (such as Reedy Lagoon) responded well, with dense cover of river swamp wallaby-grass, yellow bladderwort and wavy marshwort appearing during late spring and early summer. Vegetation responses were more limited at Black Swamp, which had a larger carp population.

Managed flows to Gunbower Forest supported many species of waterbirds to breed and successfully fledge their young, including ducks, Australasian grebes and black swans. The resident white-bellied sea eagle pairs at Little Reedy Lagoon and Little Gunbower Lagoon successfully bred in 2018, which is the third year in the row for the pair in Little Reedy Lagoon and the second time in three years for the pair in Little Gunbower. While surveys in September and October 2018 found limited signs of colonial waterbirds nesting, surveys in December 2018 at Long Lagoon found over 50 nests (about 150 juveniles present) including Australasian darter, Australian ibis, little pied cormorants, little black cormorants and great cormorant species. Most chicks fledged successfully by January 2019.

Fish surveys conducted in forest wetlands in autumn 2018 recorded less than half of the native species that would have historically used the wetlands. This result probably reflects recent drying patterns that were implemented since 2016 to remove large-bodied adult carp. Native fish communities are expected to improve in the forest wetlands if future watering events allow connections between the wetlands, Gunbower Creek and the River Murray.

Capacity constraints in Gunbower Creek mean it is not possible to simultaneously deliver large flows to Gunbower Forest and the lower reaches of Gunbower Creek. Environmental flows mainly targeted Gunbower Forest in 2018–19, and therefore flow in the lower reaches of Gunbower Creek was limited to a minimum rate that would still allow native fish to move throughout the system. The lower flow provided an opportunity to test whether native fish (including Murray cod) would spawn without the flow cues that have been provided in Gunbower Creek since 2013–14. Monitoring conducted in spring 2018 detected larvae of Murray cod, carp gudgeon, Australian smelt and flat-headed gudgeon in Gunbower Creek, but breeding rates were considerably lower than previous years. Importantly, most fish larvae were caught below Cohuna Weir, which was the reach that the flows targeted. Monitoring also detected a high abundance of waterbugs, which indicates the system is productive and likely supports the food resources that adult and larval fish need.

In May 2019, water for the environment was delivered to top up Reedy Lagoon in Gunbower Forest, to support the aquatic and amphibious wetland plants and maintain drought refugia for waterbirds, turtles and frogs.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for Gunbower Creek and Forest

Potential environmental watering action

Functional watering objective

Environmental objective

Gunbower Forest

Reedy Lagoon (top-up in winter/spring 2019)

  • Maintain the water depth to support wetland plants to flower, set
    seed and germinate
  • Maintain the water depth to provide feeding and refuge habitat for waterbirds, turtles and frogs
    Maintain the water depth and quality to provide habitat for small-bodied
    native fish including Murray-Darling rainbowfish
Fish iconFrog iconTurtle iconPlant iconHeron icon 

Little Gunbower wetland complex (fill in winter
and provide top-ups if a significant bird-breeding
event occurs)

  • Maintain the water depth to support wetland plants to flower, set seed and germinate
  • Provide feeding and refuge habitat for waterbirds and frogs

Frog iconPlant iconHeron icon

Black Swamp (fill in autumn 2020)

  • Maintain the water depth to support wetland plants to flower, set seed and germinate
  • Provide feeding and refuge habitat for waterbirds and frogs

Frog iconPlant iconHeron icon

Green Swamp, Corduroy Swamp and Little Reedy
Lagoon (fill in winter 2019)

  • Maintain the water depth to support wetland plants to flower, set seed and germinate
    Provide feeding and refuge habitat for waterbirds and frogs
  • Provide habitat for small-bodied native fish

Fish iconFrog iconPlant iconHeron icon

Winter/spring fresh in Yarran Creek (variable flow rates
and duration based on water levels in Gunbower Forest
and flows in the River Murray and Gunbower Creek)

  • Provide connectivity between Gunbower Creek and the River Murray through the Yarran Creek and Shillinglaws regulators, to increase flowing habitat for the lateral movement of native fish, turtles, carbon, nutrients and seed propagules
  • Provide migration and spawning opportunities for native fish

Fish iconJigsaw icon

Reedy Lagoon (top-up in autumn/winter 2020)

  • Maintain the water depth to support wetland plants to flower, set seed and germinate
  • Maintain feeding and refuge habitat for waterbirds and frogs
  • Maintain habitat for small-bodied native fish including Murray-Darling
    rainbowfish

Fish iconFrog iconPlant iconHeron icon

Extend natural flooding in the Gunbower Forest
floodplain, floodrunners and wetlands (with variable flow rates to maintain appropriate
inundation extent)

  • Inundate river red gum, black box and grey box communities
  • Provide access to breeding habitat and food resources for native fish
    (such as Murray cod)
  • Provide refuge habitat for waterbirds including colonial nesting species

Frog iconPlant iconHeron icon

Gunbower Creek

Winter low flows (above 300 ML/day during May to August)

  • Provide access to habitat and food resources for native fish (such as Murray cod)

Fish icon

Spring/summer/autumn high flows (targeting a gradual
increase, stable flow period and decrease in flows ranging between 300–600 ML/day during August to May)

  • Provide access to breeding habitat and food resources for native fish (such as Murray cod)
  • Provide cues for the migration and spawning of native fish

Fish icon

Year-round low flows (above
300 ML/day)1

  • Increase access to habitat and food resources for native fish

Fish icon

Increased low flows (up to 550 ML/day year-round if unregulated conditions occur in the River Murray)2

  • Increase recruitment from the River Murray populations into the creek by providing enough flow for native fish to migrate and spawn
  • Provide access to breeding habitat and food resources for native fish (such as Murray cod)

Fish icon

Spring/summer/autumn freshes (up to 550 ML/day for two to four weeks during October to April)2

  • Increase recruitment from the River Murray populations into the creek by providing cues for native fish to migrate and spawn
  • Dilute low-dissolved-oxygen water exiting Gunbower Forest below
    Koondrook Weir

Fish iconWater drop icon

1 Year-round low flows may be provided when delivery to Gunbower Forest through the Hipwell Road Channel regulator is occurring, to optimise the volume that can be delivered to the floodplain.

2 Increased low flows and freshes may be provided opportunistically in Gunbower Creek if unregulated conditions eventuate in the River Murray and the Hipwell Road Channel regulator is not being used.

Engagement

Table 2 shows the partners and stakeholder organisations with which North Central CMA engaged when preparing the Gunbower Creek and Forest 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 North Central Regional Catchment Strategy and North Central  Waterway Strategy.

Table 2 Partners and stakeholders engaged in developing the Gunbower Creek and Forest seasonal watering proposal

Partner and stakeholder engagement
  • BirdLife Australia
  • Gunbower Landcare Group
  • Individual community members
  • Individual irrigators
  • Campaspe Shire Council
  • Gannawarra Shire Council
  • Forestry businesses
  • Apiary licensees
  • Commonwealth Environmental Water Office
  • Department of Environment, Land, Water and Planning
  • Forestry Corporation of New South Wales
  • Goulburn-Murray Water
  • Murray-Darling Basin Authority
  • Parks Victoria
  • VicForests
  • Victorian Environmental Water Holder
  • Field and Game Australia
  • Gateway to Gannawarra Visitor Centre
  • Vegetation, fish and bird ecologists on the Gunbower Technical Advisory Group
  • Barapa Barapa Traditional Owners
  • Yorta Yorta Nation Aboriginal Corporation

Page last updated: 12/12/19