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 2.4 Macalister system
Table 2.4.1 Potential environmental watering actions and objectives for the Macalister River
  Potential environmental watering action
  Functional watering objectives
   Environmental objectives
   Macalister River reaches 1 and 2
      Autumn/winter low flow (90 ML/day during March to August)
  • Provide minimum depth over riffles for fish species that are migrating (i.e. Australian grayling) or about to migrate (i.e. tupong and Australian bass) downstream towards estuary habitat for spawning or breeding
• Provide permanent wetted habitat for waterbugs through minimum water depth in pools
• Provide connectivity throughout the river for the local movement of platypus and rakali (water rats), as well as protection from predation, access to food sources and to maintain refuge habitats
• Provide flows with low water velocity and appropriate depth to improve water clarity and enable establishment of submerged vegetation
• Provide sustained wetting of low-level benches (increasing water depth) to limit terrestrial vegetation encroachment
             Spring/summer low flow (90 ML/day during September to January)
 • Maintain the water depth in pools and hydraulic habitat for native fish
• Maintain permanent wetted habitat in pools and riffles for waterbugs
• Maintain shallow, slow-flowing habitat to enable the establishment of in- stream vegetation
• Maintain a minimum depth in pools to allow for turnover of water and to slow degradation of water quality to support aquatic life
• Expose and dry lower channel features for re-oxygenation
             Spring/summer fresh
(one to two freshes of 1,500 ML/day for three days during September to December)1
  • Cue the upstream migration of adult fish (e.g. short-headed lamprey), and the recruitment of juveniles (e.g. Australian grayling, tupong, common galaxias, Australian bass, short and long-finned eels) from marine/ estuarine environments
• Wet a greater area of the stream channel (increasing water depth) to limit terrestrial vegetation encroachment
• Wet mid- and higher-level benches to water woody vegetation
• Flush pools to improve the water quality and increase wetted habitat for waterbugs
• Provide flows with sufficient shear stress to flush fine sediment from small gaps to improve geomorphic habitat
             Macalister River reach 2
          Autumn fresh (one fresh of 350 ML/day for three to seven days during April to May)
• Cue the downstream migration for Australian grayling towards the estuary for spawning
• Fully flush the upper Thomson estuary (when delivered for greater than three days and combined with freshes in the Thomson River) to flush sediments from substrates, provide water quality conditions that support waterbugs and to provide freshwater to the lower Latrobe River and wetlands
      Winter fresh (one to two freshes of 700 ML/day for four to five days during June to August)
  • Cue the downstream migration towards the estuary of Australian bass for spawning and of tupong for breeding
            70 | Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21

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