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Gunbower Forest is a large, flood-dependent forest situated on the River Murray floodplain in northern Victoria between Torrumbarry and Koondrook. Covering 19,450 ha, it is bounded by the River Murray to the north and Gunbower Creek to the south.

Gunbower Forest is an internationally significant site under the Ramsar Convention and forms part of the Living Murray Gunbower–Koondrook–Perricoota 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 over the long term. This has affected the extent and condition of habitat and the health of dependent animal communities. 

Gunbower Creek is managed primarily as an irrigation carrier and supplies the Torrumbarry Irrigation Area from the River Murray. The daily variation in water levels in the creek through spring, summer and autumn is much higher now than under natural conditions due to changing irrigation demand. This significantly affects native fish populations and ecological processes. Environmental water is used to smooth out the sudden and frequent changes in water level by filling the gaps in flows caused by irrigation demand within the creek. This action supports fish migration and breeding and promotes other ecological processes while maintaining water delivery for irrigation needs. Flows linking the creek to the Gunbower Forest floodplain and the River Murray can be restored through environmental watering and are vital to enhance ecosystem function (such as carbon exchange). 

The Living Murray structural works program in the middle and lower forest was completed in 2013. The works allow up to 3,800 ha of the wetlands and floodplain to be watered with considerably less water than would be required under natural conditions. The works enable efficient watering through Gunbower Creek and the forest to maintain wetland and floodplain condition.

System map

Environmental watering objectives in Gunbower Creek and Forest

Maintain and improve the resilience of wetland plants and help river red gums recover from damage they sustained during the Millennium Drought
Maintain healthy populations of native fish species in forest wetlands and rehabilitate large- and small-bodied native fish communities in Gunbower Creek

Use flows to connect Gunbower Forest to Gunbower Creek enabling fish, insects, crustaceans, molluscs, worms and carbon to move between them, supporting the life cycle of Gunbower’s native fish
Provide feeding, breeding and refuge habitat for waterbirds including colonial nesting species
Increase the number and type of frog species in the forest

Environmental values

Gunbower Forest contains a range of important environmental values including rare and widely diverse wetland habitats, vulnerable and endangered plants and animals and large areas of remnant vegetation communities (such as river red gum forest). The forest provides a range of habitats for birds and supports internationally recognised migratory waterbirds.

Gunbower Creek provides important habitat for native fish (such as Murray cod, golden perch and freshwater catfish). Due to the large variety of native fish in the creek, it is considered to be a valuable refuge and source of fish for the recolonisation of surrounding waterways.

Social, cultural and economic values

Gunbower Creek and Forest are both valuable sites from a cultural and socioeconomic perspective. The Barapa Barapa and Yorta Yorta communities have a strong connection to the Gunbower Creek and Forest area. The Barapa Water for Country project - a partnership between Barapa Barapa and North Central CMA - has provided an opportunity for Barapa people to spend time on and re-connect with Country in and around Gunbower Forest in recent years. 

The forest provides economic values through timber production, apiculture (beekeeping), recreation and tourism. The forest and creek support numerous recreational activities including boating, kayaking, canoeing, camping, fishing and birdwatching. The Gunbower Heritage River Trail is a popular tourist attraction that highlights important Aboriginal and European cultural heritage sites. The River Red Gum Drive is one of Victoria's iconic four-wheel-drive routes and follows the River Murray track through the Gunbower National Park. 

Gunbower Creek is the major carrier for the delivery of irrigation supply to the surrounding productive lands.

Conditions mid-2017

Gunbower Forest has received six years of consecutive flooding as a result of natural and managed events. Dry conditions were expected for 2016-17 and watering objectives focused on maintaining the health of high-value wetlands - Black Swamp, Reedy Lagoon and Pig Swamp. A small volume of environmental water was pumped to Pig Swamp in upper Gunbower Forest in winter 2016 to support stressed river red gums and wetland vegetation that had not received any water since the 2011 floods. 

High rainfall in winter and spring 2016 caused natural floods in Gunbower Forest. Overbank flows from the River Murray into Gunbower Forest commenced in July and continued through to early September. Flows at Torrumbarry Weir peaked at about 52,000 ML/day and inundated at least 10,000 ha of the forest. Environmental water was delivered through one of the lower landscape regulators to enable native fish movement and carbon and nutrient cycling between the creek and forest. 

Field observations showed that river red gums responded with a flush of new growth and are in a better condition to withstand future dry conditions. Black box vegetation communities, located on the higher floodplains, were inundated for several weeks, which caused a range of aquatic understorey species including common nardoo to flourish. A high diversity of aquatic plants also germinated in some of the permanent and semipermanent wetlands. Unfortunately, there was little growth of aquatic vegetation in some wetlands (such as Greens Lagoon and Long Lagoon). The lack of response in these wetlands may be due to relatively deep water being held in them for extended periods during late spring and summer, and high turbidity caused by invasive fish species (such as carp). Although Reedy Lagoon had less wetland vegetation diversity after the flooding in spring 2016, surveys in March 2017 recorded some yellow bladderwort, a delicate carnivorous plant rarely found in Gunbower Forest.

Fewer waterbirds used the wetlands in the lower part of Gunbower Forest for feeding and breeding in 2016-17 than in previous years when environmental water was delivered (for example, in 2015-16). The main species to breed in the wetlands in 2016-17 were grey teal and pacific black ducks. Ten pairs of nankeen night herons were also observed in Little Reedy Lagoon, but is it not known whether they successfully bred. The relatively low rates of bird breeding observed in the forest's wetlands in 2016–17 may be linked to the widespread availability of breeding habitat caused by the floods in the River Murray and many of the nearby river systems.

Environmental water was provided through Gunbower Creek to support native fish outside the irrigation season. Traditionally, the creek has been drawn down to a series of disconnected deep pools at the end of the irrigation season: this is now recognised as a major factor threatening the survival of juvenile fish, particularly Murray cod. Providing environmental flows during this period maintains connections between habitats and food resources to support native fish species.

Strong recruitment of Murray cod in Gunbower Creek was observed through monitoring in 2014, corresponding to the delivery of environmental watering intended to trigger spawning of Murray cod in spring and early summer in 2013–14. Surveys in 2016–17 showed the Murray cod population in Gunbower Creek was well-represented by juvenile and subadult size classes, which is similar to populations in the River Murray considered to have sustainable levels of recruitment. These demographic patterns indicate that recently recruited juvenile and adult Murray cod are benefiting from the creek's management. Despite this, the Murray cod population in Gunbower Creek is still below the target size and requires ongoing environmental management to become self-sustaining in the long term.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Gunbower Forest

Reedy Lagoon and Black Swamp (fill in autumn/winter if the wetlands have dried completely)

  • Reduce the number of carp in permanent wetlands
  • Maintain/enhance the health and resilience of vegetation communities in permanent wetlands
  • Maintain suitable feeding, breeding and refuge habitat for waterbirds including colonial nesting species

Reedy Lagoon and Black Swamp (fill in winter/spring and provide top-ups if significant bird breeding event occurs)

  • Maintain the health and resilience of vegetation communities in permanent wetlands
  • Maintain suitable feeding and refuge habitat for waterbirds
  • Support a significant bird breeding event if one is triggered naturally

Reedy Lagoon and Black Swamp (top-ups in autumn/winter)

  • Maintain the health and resilience of vegetation communities in permanent wetlands 
  • Maintain suitable feeding and refuge habitat for waterbirds

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

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

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

  • Improve the health of river red gum communities
  • Maintain/enhance healthy populations of native fish in wetlands and increase opportunities for riverine fish to access floodplain resources
  • Maintain suitable feeding, breeding and refuge habitat for waterbirds including colonial nesting species
  • Support a significant bird breeding event if one is triggered naturally

Gunbower Creek

Winter low flows (up to 400 ML/day between July-August and May-June)

  • Increase the survival rate and maintain the growth of native fish (such as Murray cod) by maintaining access to food and habitat resources

Spring/summer high flows (targeting a gradual increase in flows up to 700 ML/day including various periods of stable flows in August-January)

  • Increase the recruitment, growth and survival of native fish (such as Murray cod) by maintaining access to breeding habitat and food resources

Summer/autumn low flows (above 300 ML/day, between January to May)

  • Maintain the survival rate and growth of native fish by increasing access to food and habitat resources

Increased winter/spring low flows (up to 500 ML/day between July–August and May–June, if unregulated conditions occur in the River Murray)

  • Increase native fish recruitment by providing cues for migration and spawning, in line with larger flows in the River Murray
  • Increase the survival rate and maintain the growth of native fish (such as Murray cod) by maintaining access to breeding habitat and food resources

Risk management

In preparing its seasonal watering proposal, North Central 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.

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.

In the North Central region communities are involved in decisions about the Loddon and Campaspe river systems, Murray river system including Gunbower Forest and some of the wetlands connected by the Wimmera-Mallee pipeline. This happens through formal advisory groups: Environmental Water Advisory Groups including river and wetland focused groups and the Gunbower Island Community Reference Group.

Who is engaged and how

Recreational users

Through formal advisory groups, recreational users provide local advice and raise opportunities for potential 'shared benefits' from environmental watering. Through Environmental Water Advisory Groups, recreational users are informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Goulburn-Murray Water engages with recreational user groups (such as Save Lake Eppalock and Lake Meran Users Group) that use water storages for recreation through planned consultations and meetings to discuss storage levels and potential impacts of environmental water releases from storages.

Environment groups

Through formal advisory groups, environment groups provide local knowledge, land management advice and advocate for the environment. They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering (including citizen science monitoring data such as providing bird counts).

Landholders/farmers

Through formal advisory groups, farmers and landholders (including those who own private wetlands that receive environmental water) provide local knowledge and land management advice regarding environmental watering.

They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering. Goulburn-Murray Water engages (and often) with consumptive entitlement holders (often irrigators) and landholders (often with river frontages).

Traditional Owners

Through the North Central Catchment Management Authority Indigenous Facilitator, Traditional Owners from the Barapa Barapa, Dja Dja Wurrung and Yorta Yorta Nations are given the opportunity to provide input to seasonal watering proposals. The Catchment Management Authority and the Barapa Barapa Nation have conducted a cultural values mapping project in Gunbower Forest which will eventually enable cultural values to be incorporated in Gunbower environmental water planning. The Barapa Barapa and Yorta Yorta Nations undertake monitoring of cultural values in Gunbower Forest.

There are Dja Dja Wurrung and Yorta Yorta representatives from the North Central region who are members of the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Holder and the Murray Darling Basin Authority engage the Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Councils

Councils are invited to participate in formal advisory groups meetings. Goulburn-Murray Water  consults with the City of Greater Bendigo, Gannawarra Shire and Swan Hill Rural City Council regularly on water management, including on environmental water management.

General public

The North Central Catchment Management Authority communicates and engages with the general public through their website, media releases, newsletters, public notices, community forums, community events (such as tours of Gunbower Forest during environmental watering), social media and direct contact to interested parties by email distribution list.