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 5.7 Loddon system
Recent conditions
The Birchs Creek catchment experienced below-average rainfall and above-average temperatures throughout 2019–20. High rainfall in August 2019 caused Newlyn Reservoir to fill and spill, which meant the VEWH forfeited allocation that was carried over from 2018–19. Newlyn Reservoir is a very small water storage and modest inflows cause it to spill in most years. The VEWH received a full allocation of 100 ML in December 2019, and that water will be available for use until 30 November 2020 unless Newlyn Reservoir spills again.
The combination of spills from Newlyn Reservoir, tributary inflows, consumptive water orders and groundwater discharge met and at times exceeded the dry scenario environmental flow recommendations for Birchs Creek during 2019–20.
Scope of environmental watering
Table 5.7.5 describes the potential environmental watering actions in 2020–21, their functional watering objectives (that is, the intended physical or biological effect of the watering action) and the longer-term environmental objectives they support. Each environmental objective relies on one or more potential environmental watering actions and their associated physical or biological functions.
Table 5.7.5 Potential environmental watering actions and objectives for Birchs Creek
 Potential environmental watering action
  Functional watering objectives
    Environmental objectives
    Spring fresh (one fresh of 30 ML/day for three days during September to November)
    • Maintain and support the growth of streamside vegetation by increasing soil moisture and depositing sediment on the bank and benches
• Scour organic matter that has accumulated in the channel and cycle nutrients throughout the creek
• Wet benches and smaller channels, to increase habitat and refuge for small fish
• Freshen refuge pools and provide connectivity between pools for fish and platypus movement
                  Autumn freshes (up to three freshes of 10 ML/day for three days during March
to April)
 • Increase the water depth, to maintain and support the growth of in-stream aquatic vegetation
• Expand riffle/run areas to provide waterbug habitat
• Top up pools to refresh water quality (particularly oxygen levels) and enhance connectivity between pools for fish and platypus movement
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