Page 125 - VEWH Seasonal Watering Plan 2020-21
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The Barwon system includes the upper Barwon River and lower Barwon wetlands.
The Barwon River flows east from the Otway Ranges passing the towns of Forrest, Birregurra, Winchelsea and Inverleigh and the City of Geelong before discharging into Bass Strait
at Barwon Heads. The Leigh and Moorabool rivers are major tributaries, joining the Barwon River at Inverleigh and Fyansford respectively. Other tributaries including Birregurra, Boundary, Callahan, Dewing, Matthews, Pennyroyal, Deans Marsh and Gosling creeks flow into the Barwon River above Winchelsea. The main storages
in the Barwon River catchments are the West Barwon and Wurdee Boluc reservoirs.
The Barwon estuary contains a Ramsar-listed system of wetlands and lakes collectively called the lower Barwon wetlands. Water for the environment can be used to manage flows in the upper Barwon River and manage water levels
in Reedy Lake and Hospital Swamps, which connect to the lower Barwon River.
3.7.1 Upper Barwon River
System overview
Flows in the upper Barwon River are regulated by the operation of the West Barwon Reservoir upstream of Forrest. Water can be released directly from the reservoir into the west branch, or into the east branch via a diversion channel. The junction of the two branches is near Boundary Creek. Upstream of Birregurra, water can be diverted into the Wurdee Boluc inlet channel, a 57 km, concrete-lined channel that transfers water to Wurdee Boluc Reservoir.
Barwon Water releases passing flows in the order of
1–5 ML per day in both the upper east and west branch (and up to 15 ML per day in September during a wet year) from the West Barwon Reservoir. Flood spills from the reservoir and natural inflows from unregulated and partly regulated tributaries add to the passing flows.
The Upper Barwon River Environmental Entitlement 2018 enables water to be made available for the environment from the West Barwon Reservoir. The entitlement provides an average of 1,000 ML per year and up to 2,000 ML
of the total storage capacity at full supply. Water for the environment was first delivered to the upper Barwon in 2018–19. The current entitlement provides only enough water to meet the highest ecological objectives in the upper Barwon east branch (reach 4) and the upper Barwon west branch (reach 3).
Environmental values
The upper Barwon River is home to native fish species including the Australian grayling, river blackfish, short-finned eel, southern pygmy perch, Australian smelt and various galaxias. The system retains some submerged aquatic vegetation, undercut banks, overhanging vegetation and riffle-pool sequences: these provide important habitat for fish and other aquatic animals.
3.7 Barwon system
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