VEWH - Gunbower Creek and Forest

Gunbower Forest is a large, flood-dependent forest situated on the Murray River floodplain in northern Victoria between Torrumbarry and Koondrook (system map below).

Covering 19,450 ha, it is bounded by the Murray River 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 Murray River 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 natural creek that has been modified to supply irrigation water from the Murray River to the Torrumbarry Irrigation Area. There are twelve lagoons, largely located in the upper reaches of the creek system, that are permanently or seasonally connected to Gunbower Creek. Water for the environment is used in Gunbower Creek to improve habitat for native fish, especially Murray cod.

The Living Murray environmental 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 watering infrastructure was not in place. The works enable efficient watering through Gunbower Creek and the forest to maintain wetland and floodplain condition and provide connectivity between the creek, forest floodplain and the Murray River. Frequent connections between the river and floodplain habitats allow biota to move between habitats and support critical ecosystem functions (such as carbon exchange).

System map

Environmental watering objectives in Gunbower Creek and Forest

Provide feeding, breeding and refuge habitat for small-bodied native fish (such as Murray-Darling rainbow fish) in forest wetlands

 Maintain and improve populations of large- bodied native fish (such as Murray cod) in Gunbower Creek

Provide suitable feeding, breeding and refuge habitat for frogs

Provide suitable feeding, breeding and refuge habitat for turtles

Support carbon and nutrient cycles in the forest and wetlands and periodically deliver carbon and nutrients from the forest to adjacent waterways to support food webs

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)

Maintain and improve water quality in Gunbower Creek

Environmental values

Gunbower Forest contains many important environmental values. It includes rare and diverse wetland habitats and large areas of remnant vegetation communities (such as river red gum forest and woodlands). It is also home to vulnerable and endangered plants and animals including river swamp wallaby-grass, wavy marshwort, Murray- Darling rainbowfish, eastern great and intermediate egrets. It also supports internationally recognised migratory waterbird species.

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.

Environmental watering objectives in Gunbower Creek and Forest

Traditional Owner cultural values and uses

At Gunbower Island there are two Traditional Owner groups which recognise the forest as their traditional Country. The mid and lower area of Gunbower Forest is recognised as the traditional Country of the Barapa Barapa people, and the upper Gunbower Forest is recognised as the traditional Country of the Yorta Yorta people. North Central CMA seeks engagement and input from both groups when undertaking annual environmental water planning and throughout the year as part of the Living Murray Indigenous Partnerships Program.

Waterway managers are seeking opportunities to increase the involvement of Traditional Owners in environmental water planning and management. Where Traditional Owners are more deeply involved in the planning and/or delivery of environmental flows for a particular site, their contribution is acknowledged in Table 5.2.5 with an icon.

Watering planned and/or delivered in partnership with Traditional Owners to support Aboriginal cultural values and uses

Barapa Barapa custodians have clearly expressed their aspirations for an active role in the management of land and water, to fulfil custodianship obligations and contribute to improvements in the health of Country.

Barapa Barapa Traditional Owners have been working inpartnership with the North Central CMA to deliver the Water for Country project in Gunbower Forest since 2015. The Water for Country project builds on the work of the previous Barapa Barapa Cultural Heritage Mapping of Lower Gunbower Forest project, delivered in 2013–14 to map a catalogue of cultural heritage assets in the forest. The Water for Country project aims to investigate how Traditional Owners’ cultural and spiritual values may be better represented in water management. In 2018, the Water for Country group has evolved to also include Wamba Wamba Traditional Owners and continues to have a focus on Gunbower Forest.

Barapa Barapa Traditional Owners identified a range of opportunities for 2020–21 watering to support cultural values (Table 5.2.3).

Social, recreational and economic values and uses

In planning the potential watering actions in Table 1, North Central CMA considered how environmental flows could support values and uses including:

riverside recreation and amenity (such as birdwatching, duck hunting and photography)
community events and tourism (such as park visitation)
socio-economic benefits (such as timber harvesting and education).

Recent conditions

Gunbower Forest and surrounding areas have had below- average rainfall and above-average temperatures for the last three years.

In 2019–20, no natural inflows entered the Gunbower Forest from the Murray River, but a managed spring high- flow event in the Murray River provided an opportunity to deliver water through Yarran Creek to facilitate fish movement between Gunbower Creek and the Murray River. Water for the environment was used in winter 2019 to fill or top-up wetlands in Reedy Lagoon and the Little Gunbower wetland complex within Gunbower Forest. In the absence of a natural flood, selected wetlands within these complexes are planned to be allowed to draw down in 2020 to reduce carp numbers, before potential top-ups in autumn 2021.

Water for the environment was also delivered to Gunbower Creek in 2019–20 to maintain habitat for native fish during winter (when irrigation flows cease) and to improve the quality of nursery habitats for native fish (especially Murray cod) during spring and summer. Annual fish surveys in Gunbower Creek have detected successful breeding and survival of Murray cod each year that water for the environment has been delivered, and the surveys are showing improved abundance and age structure within the resident Murray cod population over time.

Golden perch do not appear to breed successfully in Gunbower Creek, and there are major barriers that limit exchanges with populations in the Murray River and other connected systems. Planned works to build a fishway at Koondrook Weir in winter 2021 aim to improve connectivity between the Murray River and Gunbower Creek. This will allow large-scale fish movement to support natural recruitment within Gunbower Creek and to allow Murray cod and other species that currently breed in Gunbower Creek to disperse and contribute to broader regional populations.

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 (fill and provide top-ups in winter/ spring 2020)	Maintain water depth and extent to support the growth and recruitment of wetland plants Maintain water depth to provide feeding and refuge habitat for waterbirds, turtles and frogs Maintain depth and water quality to provide habitat for small-bodied native fish including Murray-Darling rainbowfish
Black Swamp (partial fill and provide top-ups in winter/ spring 2020)	Increase and maintain water depth and extent to support the growth and recruitment of wetland plants Provide feeding and refuge habitat for waterbirds, turtles and frogs Maintain depth and water quality to provide habitat for small-bodied native fish
Trigger-based top-up permanent and semi- permanent wetlands (variable flow rates during spring/summer as required in response to bird breeding event)	Maintain a waterbird breeding event ProvideMaintain the wetland vegetation to provide habitat for colonial nesting and flow-dependent waterbirds
Reedy Lagoon (top-up in autumn/winter 2021)	Maintain water depth to support wetland plants to grow Maintain feeding and refuge habitat for waterbirds, small-bodied native fish, turtles and frogs
Black Swamp (top-up in autumn/winter 2021)	Maintain water depth to support wetland plants to grow Maintain feeding and refuge habitat for waterbirds, small-bodied native fish, turtles and frogs
Winter/spring fresh in Yarran Creek (variable flow rates and duration based on water levels in Gunbower Forest and flows in the Murray River and Gunbower Creek)	Provide connectivity between Gunbower Creek and Murray River through the Yarran Creek and Shillinglaws regulators, to increase flowing habitat for the lateral movement of native fish, turtles, carbon and nutrients Provide migration and spawning opportunities for native fish
Little Gunbower wetland complex (fill in autumn/ winter 2021)	Increase water depth and extent to trigger wetland plants to germinate in late winter and early spring Provide feeding and refuge habitat for waterbirds, turtles and frogs Provide habitat for small-bodied native fish
Little Reedy wetland complex (including Green Swamp, Corduroy Swamp and Little Reedy Lagoon) (fill in autumn/winter 2021)	Increase water depth and extent to trigger wetland plants to germinate in late winter and early spring Provide feeding and refuge habitat for waterbirds, turtles and frogs Provide habitat for small-bodied native fish
Extend natural flooding in Gunbower Forest floodplain, floodrunners and wetlands (with variable flow rates to maintain an appropriate wetted extent during winter/spring)	Wet 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 frogs, turtles and waterbirds including colonial nesting species
Gunbower Forest floodplain, floodrunners and wetlands (with variable flow rates during autumn/winter 2021)	Wet 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 frogs, turtles and waterbirds including colonial nesting species
Gunbower Creek
Autumn/winter low flow (above 200 ML/day during May to August)	Maintain habitat and food resources for native fish (such as Murray cod) during the non-irrigation season
Spring/summer/autumn low flow (targeting a gradual increase, stable flow period and decrease in flows ranging between 300-500 ML/day during August to May)¹	Maintain breeding habitat and food resources for native fish (such as Murray cod) Provide cues for the migration and spawning of native fish Dilute low-oxygen water exiting Gunbower Forest below Koondrook Weir if required
Autumn/winter fresh (500 ML/day for one to four weeks during May to August)	Deliver in response to high flow in Murray River and low oxygen water draining off Gunbower Forest during the non-irrigation season to protect water quality and allow fish to move between Murray River and Gunbower Creek

¹ Flows may be delivered at the upper end of the range — 500 ML per day — at any time between August 2020 and May 2021 in response to unregulated flow in the Murray River or to mitigate the potential impacts of low-oxygen water exiting the Gunbower Forest below Koondrook weir.

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
Gunbower Island Community Reference Group Commonwealth Environmental Water Office Department of Environment, Land, Water and Planning Goulburn- Murray Water Murray- Darling Basin Authority (the Living Murray program and River Operations) Forestry Corporation of NSW Parks Victoria Vic Forests Gannawarra Shire Council Campaspe Shire Council Individual landholders Forestry Field and Game Australia Gateway to Gannawarra Visitor centre Vegetation, fish and bird ecologists Yorta Yorta Nation Aboriginal Corporation Barapa Barapa Traditional Owners

Partner and stakeholder engagement

Gunbower Island Community Reference Group
Commonwealth Environmental Water Office
Department of Environment, Land, Water and Planning
Goulburn- Murray Water
Murray- Darling Basin
Authority (the Living Murray program and River Operations)
Forestry Corporation of NSW
Parks Victoria
Vic Forests
Gannawarra Shire Council
Campaspe Shire Council
Individual landholders
Forestry
Field and Game Australia
Gateway to Gannawarra Visitor centre
Vegetation, fish and bird ecologists
Yorta Yorta Nation Aboriginal Corporation
Barapa Barapa Traditional Owners

Page last updated: 22/01/21