Page 73 - VEWH Seasonal Watering Plan 2020-21
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Table 2.4.1 Potential environmental watering actions and objectives for the Macalister River (continued)
2.4 Macalister system
  Potential environmental watering action
  Functional watering objectives
   Environmental objectives
  Spring fresh (one fresh of 700 ML/day for five days during September to November)
• Cue the upstream migration of adult fish (e.g. short-headed lamprey), and 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 low and mid-level benches to facilitate the dispersal of emergent and fringing vegetation throughout the reach
            Summer/autumn fresh (one to three freshes of 140 ML/ day for three to 10 days during December to May)
  • Increase the depth to allow fish to move throughout the reach
• Flush pools to maintain water quality for aquatic animals
• Flush substrates and improve the quality of existing waterbug habitat and food supply
• Wet low benches to facilitate the longitudinal dispersal of emergent vegetation
• Provide flows with sufficient shear stress to flush fine sediment from small gaps to improve geomorphic habitat
             Trigger-based summer/ autumn low flow (35–60 ML/day during December to May)2
 • Maintain permanent wetted habitat in pools and riffles for aquatic animals
• Maintain shallow, slow-flowing habitat to maintain 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
          1 This fresh is only planned to be delivered following a spill in Lake Glenmaggie (if the magnitude is lower than minor flood level), to extend or slow the rate of ramp-down. If a spill occurs, delivering this fresh will meet the functional flow objectives of the lower magnitude spring/summer fresh.
2 A low flow of 35–60 ML per day may be triggered if passing flows from Maffra Weir reduce or cease.
                  Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21 | 71

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