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The Coliban River is the major tributary of the Campaspe River and flows into Lake Eppalock. It is highly regulated with three storages harvesting water primarily for urban use.

The Coliban River continues to be an important place for Traditional Owners and their Nations. The Registered Aboriginal Party in the region is the Dja Dja Wurrung Clans Aboriginal Corporation who were engaged during the preparation of the Coliban seasonal watering proposal.

Environmental watering objectives in the Coliban River

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Support platypus communities by providing opportunities for successful breeding and dispersal
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Improve water quality and maintain healthy levels of dissolved oxygen in pools
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Increase the cover and diversity of aquatic plants Increase the cover and diversity of fringing vegetation while limiting encroachment into the middle of the channel Maintain adult riparian vegetation and provide opportunities for recruitment
Increase the abundance and diversity of smallbodied native fish by providing flows that allow movement
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Maintain adequate diversity and biomass of waterbugs to break down dead organic matter and support the river’s food chain
Clean fine sediment from substrates to support biofilms

Environmental values

The Coliban River provides important habitat for platypus, native water rats and small-bodied native fish (such as flatheaded gudgeon and mountain galaxias). The Coliban River also contains a diverse range of waterbugs supported by stands of emergent and submergent aquatic vegetation. It is bordered by remnant patches of streambank shrubland vegetation and woodland containing river red gum, callistemon, woolly tea-tree and inland wirilda, which provide habitat for terrestrial animals.

Social and economic values

Communities in Malmsbury, Taradale, Metcalfe and the surrounding area value the Coliban River for its aesthetic and recreational features including Ellis Falls and the Cascades. Popular recreational activities in the area include camping, fishing and birdwatching. The upper Coliban storages – the Malmsbury and Lauriston reservoirs – supply urban, irrigation, stock and domestic demands in the surrounding area.

Conditions 2018

Rainfall in the Coliban River area for the 2017–18 season has been variable although generally below average. Rainfall between August and November is essential for filling the Coliban storages. Rainfall between August and November 2017 was 165 mm, which is slightly less than the long-term average of 191 mm. For most of the year, there was little-to-no contribution of unregulated flows from catchment run-off, so flows in the Coliban River were generally well-below environmental flow recommendations. The exception was a small spill from Malmsbury Reservoir in September.

Passing flows were reduced to 4 ML per day during winter/spring to enable managers to build a reserve in the Malmsbury passing flows account that could be used to maintain continuous flows in the upper reaches over summer: otherwise, flows would stop completely. Even with the release of accumulated passing flows, the lowest reaches of the Coliban River contracted to a series of isolated pools in summer/autumn

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Coliban system

Potential environmental watering

Environmental objectives

Pulsed summer/ autumn low flow (5–15 ML/day for up to 2 weeks in December– May as required)1

  • Maintain water quality (including dissolved oxygen levels) and habitat for aquatic biota (including fish and platypus

Summer/autumn low flow (1–10 ML/day in December–May)

  • Maintain water quality (including dissolved oxygen levels) and habitat for aquatic animals (including fish and platypus) 
  • Maintain aquatic and fringing vegetation
  • Maintain waterbug habitat

Summer/autumn freshes (2 events of up to 200 ML/day for 3 days in December– May)1

  • Support fish and platypus movement during the summer period 
  • Maintain aquatic and fringing vegetation
  • Improve water quality and waterbug habitat
  • Flush organics and sediment from in-stream substrates

1The actual volume and duration of freshes will depend on available water resources, climatic conditions and conditions within the river.

Risk management

In preparing its seasonal watering proposal, North Central CMA considered and assessed the risks of environmental watering and identified mitigation strategies. Program partners continually reassess risks and mitigation actions throughout the water year.

Engagement

Table 2 shows the partners and stakeholder organisations the North Central CMA engaged in preparing the Campaspe system 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 the North Central Waterway Strategy.

 Table 2 Partners and stakeholders engaged in developing the Campaspe system seasonal watering proposals

Partner and stakeholder engagement
  • Campaspe Environmental Water Advisory Group (comprising community members, Department of Environment, Land, Water and Planning, GoulburnMurray Water, North Central CMA, the Victorian Environmental Water Holder and the Commonwealth Environmental Water Office) 
  • Coliban Water 
  • Dja Dja Wurrung Clans Aboriginal Corporation 
  • Dja Dja Wurrung Traditional Owners 
  • Taungurung Clans Aboriginal Corporation 
  • Yorta Yorta Nation Aboriginal Corporation