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

Flow in the Coliban River below Malmsbury Reservoir is regulated by the operation of the Malmsbury, Lauriston and Upper Coliban storages. An important distinction between the Coliban River and other regulated Victorian systems is the lack of irrigation demand. Therefore, flow in the river is influenced by the passing flow entitlement, which depends on catchment inflows and major flood events in the catchment.

Reach 1 of the Coliban River below Malmsbury Reservoir to Lake Eppalock can benefit from environmental watering. The VEWH does not have any environmental entitlements in the Coliban system, but passing flows can be managed — for example, they can be accumulated and released when most needed — to help mitigate some risks associated with critically low summer/autumn flow including low oxygen levels. A small volume of Commonwealth environmental water is held in the system, but the high cost of delivery means there is no plan to use it in 2020–21.

Traditional Owners
Environmental water holder

Environmental watering objectives in the Coliban River

Increase the abundance and diversity of small- bodied native fish
Platypus icon
Increase platypus communities by providing opportunities for successful breeding and dispersal
Plant icon
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 streamside woody vegetation and facilitate recruitment
Insect icon
Maintain adequate diversity and biomass of waterbugs, to break down dead organic matter and support the river’s food chain
Water icon
Improve water quality and maintain healthy levels of dissolved oxygen in pools

Environmental values

The Coliban River provides important habitat for platypus, rakali (water rats) and small-bodied native fish (such as flat-headed 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 stream bank shrubland vegetation and woodland containing river red gum, callistemon, woolly tea-tree and inland wirilda, which provide habitat for terrestrial animals.

Traditional Owner cultural values and uses

In planning for environmental flows in the Coliban River, Dja Dja Wurrung Clans Aboriginal Corporation and North Central CMA have considered how environmental water management assists with preservation of historical and contemporary cultural values including promoting a sense of place and spiritual connection.

The Dja Dja Wurrung Country Plan describes their aspirations around the management of rivers and waterways and articulates Dja Dja Wurrung peoples’ support for the reinstatement of environmental flows as an overall objective for the management of water on Country. The North Central CMA and Dja Dja Wurrung Clans Aboriginal Corporation continue to work towards increased engagement on planning and delivery of environmental watering activities, including identifying opportunities for Dja Dja Wurrung involvement.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 1, North Central CMA considered how environmental flows could support values and uses including:

  • water-based recreation (such as canoeing and fishing)
  • riverside recreation and amenity (such as birdwatching, camping, cycling and walking)
  • community events and tourism (such as visitation)
  • socio-economic benefits (such as diverters for irrigation, domestic and stock uses, community wellbeing and benefits to the local economy from visitors).

Recent conditions

Rainfall in the Coliban River catchment was below the long-term average for every month during 2019–20, except in November and January. Daily maximum temperatures were generally above average, and December 2019 was exceptionally hot. Carryover from the previous year, along with some unregulated inflows in the Coliban River from July to September 2019, facilitated the accumulation of passing flows.

The flow varied along the length of the Coliban River throughout 2019–20. The Coliban River began contracting above Lake Eppalock towards Malmsbury Reservoir from October 2019 onwards, as the flow dried up along the river. Inflows from unregulated tributaries delivered several natural freshes to the whole system between July and September 2019. Passing flows that were accumulated in winter/ spring were used to maintain low flow between Malmsbury Reservoir and Lake Eppalock throughout summer/autumn. Accumulated passing flows were also used to deliver a fresh to improve water quality for aquatic biota in this section of the river in March 2020.

In 2019–20, the priority pulsed low flow in summer and autumn for maintaining water quality was not required, as there was enough water to maintain a reduced summer/ autumn low flow in the upper sections of the river. However, the water available was insufficient to maintain full connectivity of the river to Lake Eppalock, and the lower reaches contracted to a series of pools in summer.

Scope of environmental watering

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

Potential environmental watering action

Functional watering objective

Environmental objectives

Pulsed summer/autumn low flow (five to 15 ML/day for one to 14 days during December to May)

  • Maintain water quality including oxygen levels
  • Maintain refuge habitat for aquatic animals, including fish and platypus
Fish iconPlatypus iconWater drop icon

Summer/autumn low flow (one to 10 ML/day during December to May)

  • Maintain aquatic habitat that support waterbugs, native fish, platypus and fringing vegetation
  • Maintain water quality including oxygen levels
Fish iconPlatypus iconPlant iconInsect iconWater drop icon

Summer/autumn freshes (one to two freshes of 25-160 ML/day for one to three days during December to May)

  • Maintain the water depth through rifle-run habitats of five to 20 cm for a 25-50 ML/day event to maintain water quality and habitat for waterbugs
  • Maintain water depth through rifle-run habitats of 45–55 cm for a 160 ML/ day event to:
  • increase water depth to facilitate fish and platypus movement
  • clean sediment and biofilms from river substrates
  • wet benches and low banks to promote the growth and recruitment of fringing vegetation
Fish iconPlatypus iconPlant iconInsect iconWater drop icon

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
  • Coliban Water
  • Common- wealth Environmental Water Office
  • Department of Environment, Land, Water and Planning (land manager)
  • Game Management Authority
  • Individual Landholders and community members
  • VRFish
  • Dja Dja Wurrung Clans Aboriginal Corporation

Page last updated: 24/07/20