Page 51 - VEWH Seasonal Watering Plan 2020-21
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Table 2.2.1 Potential environmental watering actions and objectives for the Latrobe River
2.2. Latrobe system
  Potential environmental watering action
  Functional watering objectives
    Environmental objectives
   Summer/autumn low flow (250 ML/day or natural during December to May)
 • Maintain an adequate depth in pool habitat to support aquatic animals and submerged vegetation
• Limit encroachment by terrestrial vegetation and support the growth of emergent macrophyte vegetation
• Maintain oxygen levels in pools
• Maintain sediments in suspension to prevent pools filling
                       Summer/autumn river fresh (one to four freshes of 920 ML/day for one to five days during December to May)
 • Wet benches to maintain habitat and support the growth of emergent macrophyte vegetation
• Freshen water quality to support waterbug and zooplankton communities
• Flush sediment (sands and silts) from pools and mix water in pools, helping to provide spawning conditions for Australian grayling and breeding substrate for river blackfish
• Provide longitudinal connectivity for aquatic animals
                     Summer/autumn estuary fresh (one to three freshes of 2,200 ML/day at reach 6 for seven to 10 days during December to May)
        Objectives listed for the summer/autumn river fresh and additional objectives for the Latrobe River estuary:
• upper estuary: fully flush with freshwater to support submerged vegetation, provide suitable conditions including oxygen levels for aquatic animals, transport silt, wet benches and deliver freshwater to connected wetlands
• mid-estuary: partially/fully flush the upper layer of the water column to improve water quality, support emergent macrophytes, provide freshwater habitat and associated food sources for freshwater fish and provide breeding opportunities for estuary fish
• lower estuary: partially flush the upper layer of the water column; a flow of this magnitude will also provide opportunities to fill to the lower Latrobe wetlands
Note: This event requires contributions of at least 1,280 ML/day from the Thomson River at Bundalaguah over the equivalent period to meet objectives
                       Winter/spring fresh (one to two freshes of 3,200 ML/ day at reach 6 for two days during June to November)1
     Latrobe River objectives:
• wet banks and higher benches to improve the condition of streamside vegetation
• provide a variety of wetted areas for emergent macrophytes
• maintain channel capacity and bench habitat
Additional objectives for the Latrobe River estuary:
• upper estuary: fully flush with freshwater to support submerged vegetation, increase oxygen levels for aquatic animals, transport silt, wet benches and deliver freshwater to connected wetlands
• mid-estuary: partially/fully flush the upper layer of the water column to improve water quality, support emergent macrophytes, provide freshwater habitat and associated food sources for freshwater fish and provide breeding opportunities for estuary fish
• lower estuary: partially flush the upper layer of the water column; a flow of this magnitude will also provide opportunities to fill to the lower Latrobe wetlands
Note: Delivering the target flow event in the estuary will require contributions of 1,000–2,200 ML/day from the Thomson River at Bundalaguah over the equivalent period to meet objectives
                  Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21 | 49
 


































































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