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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. High water levels in the Barwon River can also result in natural inundation of the wetlands.

Environmental water holder

System map

Grey river reaches have been included for context. The coloured extent of the upper Barwon River (including the East and West branches) is provided as a preliminary indication of where water may be able to be delivered if the entitlement is granted.

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
Plant icon
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
bird icon
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 about 47 threatened plant and animal species and communities. These include some of Victoria’s rarest species (such as the brolga, orangebellied 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 inundated from the 1970s until 2016. Permanent inundation favoured the reed bed community in the lake and over time it has increased its extent and replaced much of the coastal saltmarsh and herbfield communities and open-water habitat. While reed beds form an important part of the lake’s ecosystem, their continued expansion has reduced habitat diversity and the number and diversity of internationally-important migratory waterbirds that are able to use the wetland.

The Corangamite CMA and the VEWH have implemented the first three years of a four-year watering regime at Reedy Lake which includes three years of partial summer/ autumn drying and one year of full summer inundation.

The new water regime has already helped to control carp numbers and improve conditions for communities of coastal saltmarsh and herbfields. Achieving a more natural wetting and drying regime will continue to improve the ecology of the lower Barwon wetlands.

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

Recent conditions

Hospital Swamps and Reedy Lake underwent a wetting and drying regime in 2018–19. Water levels in the wetlands peaked in July 2018 in response to localised rainfall. High water levels in winter promoted major fish breeding and recruitment opportunities and supported the growth of vegetation, which provides summer feeding habitat for waterbirds.

Structures that control inflow from Barwon River to the wetlands were closed in November 2018 to allow water levels to draw down slowly over summer. The outlet structure at Reedy Lake was opened shortly after, to allow water levels to fluctuate with tidal influences.

The inlet structures remained closed for longer than normal, because at the end of the planned wetland drying cycle water levels in the Barwon River were below the permissible level of diversion (0.7 m AHD) at the lower barrage gauging station. The inlet structures were opened in late March 2019 and temporarily closed in April 2019, again due to low river levels.

Scope of environmental watering in 2019-20

Table 1 shows potential environmental watering actions and associated environmental objectives.

Potential environmental watering action

Functional watering objective

Environmental objective

Reedy Lake

Autumn/winter/spring fill and
top-ups (all year)1

The inlet to Reedy Lake will be opened in autumn in response to a sustained
increase in flows in the Barwon River

  • Maintain the water level at or above 0.8 m AHD (allowing for natural fluctuations)
  • Maintain connectivity with the Barwon River
  • Inundate the vegetation at the wetland margins to provide feeding habitat for waterbirds
  • Provide rising water levels to promote waterbird breeding
  • Promote major fish breeding and recruitment opportunities
  • Allow fish to move between the river, lake and estuary
Fish iconPlant icon  Heron icon

Hospital Swamps

Autumn/winter/spring fill and top-ups (during March and April to December)1

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

  • Create habitat to support waterbug and fish populations
  • Stimulate 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 icon

Summer/autumn drawdown (during December to March and April)


The inlet to Hospital Swamps will be closed to allow water levels to drop through evaporation; during this period, the outlet will be opened for short periods
of time if a summer storm increases water levels above 0.85 m AHD to reduce levels.

  • Reduce the threat of carp and associated impacts on native plants and animals
    Prevent the expansion of tall reeds by increasing the salt content of the water and soil
    Increase habitat diversity (including in salt pans, mudflats and shallow water)
  • Provide wading bird habitat in early summer
    Provide refuge and foraging habitat for waterbirds in early summer
  • Increase lake shore salinity and increase soil salinisation
  • Initiate the decomposition of organic matter on the wetland bed, to increase lake productivity when it is refilled
  • Improve soil health and allow weathering of heavy metals in lake fringe soils
  • Provide suitable conditions for threatened vegetation communities (such as coastal saltmarsh, herbfields and lignum shrubland)
  • Allow seasonal recruitment of aquatic macrophytes at the wetland fringes

Fish iconcracked iconPlant iconHeron icon

1 Water can only be diverted into the lower Barwon wetlands when water levels in the Barwon River are above 0.7 m AHD at the Lower barrage gauging station, in line with provisions for accessing water conditions of the environmental entitlement.

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

Partner and stakeholder engagement
  • Environment Victoria
  • Geelong Environment Council
  • Geelong Field Naturalists Club
  • Lower Barwon Community Advisory Committee
  • Victorian Fisheries Authority
  • Individual landholders
  • Commercial eel fishers
  • City of Greater Geelong
  • Barwon Water
  • Department of Environment, Land, Water and Planning
  • Parks Victoria
  • Southern Rural Water
  • Victorian Environmental Water Holder
  • Field and Game Australia
  • Geelong Gun and Rod Association
  • VRFish
  • Wathaurung Aboriginal Corporation
  • Federation University
  • RMIT University

Page last updated: 12/12/19