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Birch Creek is part of the broader Bullarook system which contains two small storages — Newlyn Reservoir and Hepburn Lagoon — which provide water for irrigation and urban supply. The storages fill and spill during winter or spring in years with average or above-average rainfall.

Birch Creek receives tributary inflows from Rocky Lead, Langdons, Lawrence and Tourello creeks. In the downstream reaches, Birch Creek is highly connected to groundwater, which provides baseflows to the creek in most years.

The VEWH is allocated 100 ML in Newlyn Reservoir on 1 December each year, provided that seasonal determinations in the Bullarook system are at least 20 percent. Any unused allocation from 1 December can be carried over until 30 November of the following water year, but if Newlyn Reservoir spills from 1 July to 30 November, the volume held in carryover is lost. Any water remaining on 30 November is forfeited. When seasonal determinations are below 20 percent, the VEWH does not receive an allocation, and the system’s resources are shared equitably to protect critical human and environmental needs.

Environmental watering objectives in Birchs Creek

Increase the population and diversity of small-to-medium-bodied native fish including river blackfish, mountain galaxias, flat-headed gudgeon and Australian smelt, and provide opportunities for movement between pool habitats
Platypus icon
Maintain the breeding population of platypus and provide opportunities for its dispersal to Creswick Creek and Tullaroop Creek
Plant icon
Maintain and improve the diversity and abundance of in-stream aquatics

Maintain a diverse variety of fringing and riparian native vegetation communities
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Increase the population of waterbugs and the diversity of functional groups
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Maintain water quality to support aquatic life and ecological processes

Environmental values

Birch Creek supports threatened aquatic plants and its deep pools provide habitat for aquatic animals during dry periods. The creek contains native fish including regionally significant populations of river blackfish and mountain galaxias as well as flat-headed gudgeon and Australian smelt. Recent monitoring indicates that platypus are present throughout the entire creek.

The removal of willows along the creek in 2018 has led to observed improvements in in-stream vegetation and presence of small-bodied fish.

Recent conditions

The Birch Creek catchment had below-average rainfall in winter and spring 2018–19, with October being well- below average. Despite the dry winter and spring, flows in the creek were maintained from groundwater baseflow, consumptive water and small releases from Hepburn Lagoon. Summer and autumn were warmer and drier than average, and flows in Birch Creek throughout these seasons were low, but sufficient to maintain aquatic habitat and water quality.

Newlyn Reservoir did not spill in 2018–19, but tributary inflows and groundwater discharge contributed to meeting environmental flow objectives in Birch Creek throughout the year; and no environmental flows were delivered in 2018–19.

The system allocation was above 20 percent on 1 December 2018, meaning the 2018 allocation of water for the environment became available. The 2018 reserve will be available for use until 30 November 2019.

Significant willow removal occurred along Birch Creek in 2018, particularly in the Smeaton area. This may have increased flow rates, but this has not been confirmed. Processes such as scouring and sediment transport are more evident since the removal of the trees, and observations indicate the recolonisation of in-stream vegetation and small-bodied fish.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for Birchs Creek

Potential environmental watering

Functional watering objective

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 providing moisture and sediment to 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 provide increased habitat and refuge for small fish
  • Freshen refuge pools and provide connectivity between pools for fish and platypus movement
Fish iconPlant iconWater drop iconPlatypus iconInsect icon

Summer/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 dissolved oxygen) and enhance connectivity between pools for fish and platypus movement
Fish iconPlant iconWater drop iconPlatypus iconInsect icon

Engagement

Table 2 shows the partners and stakeholder organisations with which North Central CMA engaged when preparing their seasonal watering proposals.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the North Central Regional Catchment Strategy and North Central  Waterway Strategy.

Table 2 Partners and stakeholders engaged in developing the Loddon system seasonal watering proposal

Partner and stakeholder engagement
  • Parks Victoria
  • Individual Landholders
  • Goulburn- Murray Water
  • Victorian Environmental Water Holder
  • Department of Environment, Land, Water and Planning
  • Dja Dja Wurrung Clans Aboriginal Corporation