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The estuarine reach of the Barwon River contains a system of wetlands and lakes including Lake Connewarre, Reedy Lake, Hospital Swamps, Salt Swamp and Murtnaghurt Lagoon. Water for the environment can be used to manage water levels in Reedy Lake and Hospital Swamps, which connect to the Barwon River.

The environmental entitlement for the lower Barwon wetlands does not provide access to water held in storage. Instead, it allows water to be diverted from the Barwon River into Reedy Lake and Hospital Swamps when river levels are above 0.7 m AHD (Australian Height Datum). High water levels in the Barwon River can also result in natural wetting of the wetlands.

Traditional Owners
Environmental water holder

System map

Environmental watering objectives in the Lower Barwon wetlands

Fish icon
Provide habitat for fish breeding and growth and improved conditions for migration and dispersal, when wetlands are connected to the Barwon River
Soil icon
Provide varying water levels and conditions to promote soil salinisation, to support the persistence and growth of threatened saltdependent ecological vegetation communities
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Maintain the high diversity of ecological vegetation communities in the wetlands Increase the growth and extent of coastal saltmarsh, herbfields and lignum shrubland ecological vegetation communities
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Maintain and improve the waterbug population and its biomass
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Maintain nutrient cycling and improve lake productivity

Provide flushing inflows to remove accumulated salts

Maintain surface water and groundwater interactions
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Provide suitable foraging habitat including mud flats and shallow water for wading birds, and refuge for waterbirds and shorebirds

Environmental values

Reedy Lake and Hospital Swamps form part of the internationally-recognised Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar site, which is used by many thousands of migratory birds from around the world. The wetlands support 47 known threatened plant and animal species and communities. These include some of Victoria’s rarest species (such as the brolga, orange bellied parrot, Australasian bittern, growling grass frog, Australian grayling and dwarf galaxias) and subtropical and temperate coastal saltmarsh communities.

Reedy Lake supports a range of vegetation communities including coastal saltmarsh, herbfields and reed beds. Reedy Lake was a partly ephemeral system, but river regulation meant the lake was permanently wetted from the 1970s until 2016. This long-term wetting resulted in a decline in biodiversity. The full water levels reduced the extent and diversity of vegetation communities including coastal saltmarsh, and they reduced the availability of shallow wading habitat which in turn has resulted in lower waterbird diversity.

In 2016–17, Corangamite CMA and the VEWH implemented a four-year watering regime trial at Reedy Lake to reinstate a more natural wetting and drying cycle. The 2019–20 water year was the final year of the trial — three years of partial drying and one year completely full — and a review of the recommended regime is currently underway. The recommendations from the review will inform the 2020–21 watering actions and determine future directions. The lower Barwon wetlands section of the seasonal watering plan will be updated by September 2020 to reflect the review’s recommendations.

Hospital Swamps is made up of five wetland basins that support important ecological processes and significant ecological values including large areas of threatened coastal saltmarsh and diverse waterbird communities. Vegetation communities in Hospital Swamps have remained largely unchanged over time due to the maintenance of natural wetting and drying cycles.

Traditional Owner cultural values and uses

Corangamite CMA worked with Wadawurrung Traditional Owners during the development of environmental watering plans for the lower Barwon wetlands, as part of an ongoing conversation to ensure Wadawurrung knowledge and culture is incorporated into decision-making, and that watering requirements for culturally-significant species are maintained.

As part of this partnership, the Wadawurrung have identified cultural values which are applicable to all waterways within Wadawurrung Country. Values that have been identified in the lower Barwon wetlands include:

  • culturally significant wetland species, such as Porronggitj (brolga), Toolim (black duck), Kunuwarra (black swan), Buniya (eel), Tark (common reed) and Bal- yan (bull rush)
  • recognition of wetlands as meeting, ceremony and trade places
  • maintaining access to culturally important story places and ceremonial places
  • protection of artefact sites.

Social, recreational and economic values and uses

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

  • water-based recreation (such as fishing and duck hunting)
  • riverside recreation and amenity (such as birdwatching and spending time outdoors)
  • socio-economic benefits (such as commercial fishing).

Recent conditions

Rainfall across the lower Barwon River catchment in 2019–20 was close to the long-term average. High rainfall in winter 2019 and in late summer to autumn 2020 contributed high flows in the river and delivered water to Reedy Lake and Hospital Swamps.

Water levels in Reedy Lake varied between 0.6 m and 1.0 m AHD throughout 2019–20. This followed three successive years of managed partial drying, where the lake was filled in winter and then allowed to draw down during summer and autumn. Monitoring at Reedy Lake over the last four years indicates the drying regime has improved the diversity of vegetation, increased species richness of brackish aquatic herbland plants and increased the abundance of waterbirds including Australasian bitterns and magpie geese.

In 2019–20, Hospital Swamps was filled in winter and then drawn down to 0.3 m AHD over summer.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the lower Barwon wetlands1

Potential environmental watering action

Functional watering objective

Environmental objective

Reedy Lake

Winter/spring fill (July to September)

The inlet to Reedy Lake will be opened to allow high flows in the Barwon River to flow into the wetland

  • Maintain the water level at or above 0.8 m AHD (allowing for natural fluctuations)
  • Maintain waterbird breeding events
  • Wet the vegetation at the wetland margins to provide feeding habitat for waterbirds
  • Maintain fish breeding and recruitment opportunities
  • Allow fish to move between the river, lake and estuary
Fish iconPlant icon  Heron icon

Hospital Swamps

Winter/spring fill (July to September)

Hospital Swamps will be connected to the Barwon River for at least six weeks by keeping the inlet and outlet open

  • Maintain the water level at 0.5 m AHD (allowing for natural fluctuations)
  • Create habitat to support waterbug and fish populations
  • Improve fish and waterbird breeding
  • Allow fish to access the wetland from the river
  • Dilute salt in the soil and surface water over winter
  • Promote and sustain the growth of important wetland vegetation communities

Fish iconPlant iconHeron iconInsect iconWater drop icon

1 The table only includes potential watering actions for July–September 2020. Potential watering actions for the rest of the year will be based on the independent review of the lower Barwon wetlands watering trial 2016–17 to 2019–20.

Engagement

Table 2 shows the partners, stakeholder organisations and individuals with which Corangamite CMA engaged when preparing the lower Barwon wetlands 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 Corangamite Regional Catchment Strategy and the Corangamite Waterway Strategy.

Over the last six years, the Corangamite CMA has consulted extensively about the planned watering regimes for Reedy Lake and Hospital Swamps with diverse stakeholders and interest groups representing over 1,500 people. These people have been involved in developing the original environmental flows study and in subsequent scientific work about ecological risks, vegetation monitoring, alternative management approaches and infrastructure operations. The results of this work show that lowering water levels at Reedy Lake is the only feasible management practice that will mitigate threats to the ecological health of the wetland and ensure all user groups can continue to use the system in future.

Table 2 Partners and stakeholders engaged in developing the lower Barwon wetlands seasonal watering proposal

Partner and stakeholder engagement
  • Community members on the Lower Barwon Community Advisory Committee
  • Members of the Lower Barwon Review Project Advisory Group
  • Environment Victoria
  • Geelong Environment Council
  • Geelong Field Naturalists Club
  • Barwon Water
  • Department of Environment, Land, Water and Planning
  • Parks Victoria
  • Southern Rural Water
  • Greater Geelong City Council
  • Victorian Fisheries Authority
  • Landholders
  • Farmers
  • Commercial eel fishers
  • Geelong Field and Game
  • Geelong Gun and Rod Association
  • VR Fish
  • Lower Barwon Review 2020 Expert Review Panel
  • Wathaurung Aboriginal Corporation

Page last updated: 24/07/20