Page 130 - VEWH Seasonal Watering Plan 2020-21
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 3.7 Barwon system
3.7.2 Lower Barwon wetlands
System overview
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.
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.
Environmental watering objectives in the lower Barwon wetlands
Provide habitat for fish breeding and growth and improved conditions for migration and dispersal, when wetlands are connected to the Barwon River
Reduce carp populations
Provide varying water levels and conditions
to promote soil salinisation, to support the persistence and growth of threatened salt- dependent ecological vegetation communities
Improve soil health and enable the weathering of heavy metals in vegetation fringe soils
Increase the diversity of ecological vegetation communities in the wetlands and improve the recruitment of aquatic vegetation
Increase the growth and extent of coastal saltmarsh, herbfields and lignum shrubland ecological vegetation communities
Reduce tall reed extent and increase open water habitat
Maintain and improve the waterbug population and its biomass
Maintain nutrient cycling and improve lake productivity
Provide flushing inflows to remove accumulated salts
Maintain surface water and groundwater interactions
Provide suitable feeding and breeding habitat for waterbirds, including mud flats and shallow water for wading birds, flooded vegetation and wetland fringes
Maintain and increase waterbird breeding events
128 | Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21

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