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The Tarago River has its headwaters in the Tarago State Forest and flows into the Tarago Reservoir at Neerim, which sits in the upper reaches of the Tarago River and harvests inflow from all upstream tributaries. Downstream of the reservoir, the river flows close to the town of Rokeby before meeting the Bunyip River (of which it is a major tributary) at Longwarry North. From there, the Bunyip River flows through a straightened channel, Bunyip Main Drain, to flow into Western Port Bay. This downstream reach supplies many irrigators in the catchment.

Water available under the Tarago environmental entitlement is stored in and released from Tarago Reservoir. Reach 2 from below the reservoir to the confluence of the Tarago and Bunyip rivers is the target reach, as it has high ecological value with a high diversity of native fish and patches of native fringing vegetation. Environmental water deliveries to reach 2 often achieve the desired flows in reach 6.

Waterway manager
Storage manager
Environmental water holder

System map

Tarago System
Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches can receive environmental water.

Environmental watering objectives in the Tarago River

Plant icon
Improve health and increase diversity of native riverside vegetation
Fish icon
Protect and boost native fish populations including threatened species (the Australian grayling and river blackfish) by providing habitat and triggers for fish to migrate and spawn
Insect icon
Provide habitat and food for waterbugs
Platypus icon
Maintain and improve foraging habitat for platypus

Environmental values

The Tarago system contains several significant and threatened native plant and animal species including the Australian grayling, long pink-bells, tree geebung and swamp bush-pea. The upper catchment has healthy riparian vegetation and highly diverse in-stream habitat that supports native fish including river blackfish and mountain galaxias. While the lower catchment has been highly modified, it contains good patches of remnant vegetation and healthy populations of Australian grayling and platypus.

Social, cultural and economic values

There are several reserves, picnic areas and designated fishing locations along the length of the Tarago system as well as a popular caravan park and public land in the headwaters. These all contribute to the social and recreational value of the Bunyip and Tarago rivers. Many irrigators rely on water from the Tarago system and urban supplies are also provided from the storage.

The Tarago River runs through the traditional lands of the Kurnai and Kulin Nations which have many Traditional Owner groups. The waterways of this region were would have been a focus for Aboriginal communities before European settlement due to their permanent water supply and associated resources. Aboriginal Victorians have a continuing connection to the waterways of this region and in recent times the Robin Hood Reserve on the Tarago River has been an important meeting place for them.

Conditions mid-2017

Regular winter/spring rainfall caused Tarago Reservoir to spill between September and December 2016. The spills provided increased flows and variability in the river downstream of the reservoir, which achieved most of the targeted environmental flows in spring. Conditions began to dry through summer and into autumn, due to warmer weather and less rainfall.

Environmental water was released in January and March 2017 to provide two summer/autumn freshes. These events aimed to increase habitat availability for animals and clear sand bars of encroaching vegetation. A third summer/ autumn fresh was delivered in May 2017, primarily to trigger migration of Australian grayling to spawn.

Monitoring results show a clear link between environmental flow releases and Australian grayling migration and spawning, with the length of the release being critical to initiate successful spawning. Other monitoring has shown environmental water releases in the Tarago River also improve the quality and quantity of food and habitat for platypus and increase opportunities for these animals to move.

Scope of environmental planning

Table 1. Potential environmental watering actions and objectives for the Tarago River

Potential environmental watering

Environmental objectives

Summer/autumn freshes (5 freshes of 100 ML/day for 4 days each in December–May)

  • Prevent vegetation growing on sand bars, scour holes in the riverbed,
    improve water quality and allow the migration to suitable habitat of
    aquatic species, particularly fish

Autumn high flow (1 high flow of 100 ML/day for at least 2 days during April–May)

  • Trigger the downstream dispersal and spawning of Australian grayling

Spring/summer high flow (1 high flow of 280 ML/day for 4 days during October–December)

  • Inundate barriers in the river to allow fish passage, specifically juvenile Australian grayling migration

Winter/spring freshes (up to 4 freshes of 280 ML/ day for 3 days during June–November)

  • Mobilise sand and sediment to maintain and create habitat variability for waterbugs and to maintain riparian vegetation

Summer/autumn low flows (12 ML/day [or natural] during December–May)1

  • Maintain water quality and provide habitat for river blackfish, Australian grayling, platypus and waterbugs

Winter/spring low flows (100 ML/day [or natural] during June–November)2

  • Inundate littoral habitats for juvenile fish
  • Increase the availability of riverbed habitat for waterbugs
  • Promote the recruitment and increase the diversity of native riparian vegetation types and prevent terrestrial vegetation encroachment

1 Summer/autumn low flows are generally provided by passing flows under the environmental entitlement but during dry conditions it may be necessary to supplement these flows using environmental water.

2 Winter/spring low flows are unlikely to be delivered as the volume required would severely affect the ability to provide other environmental flow events.

Risk management

In preparing its seasonal watering proposal, Melbourne Water 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

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

Communities in the Melbourne region are involved in decisions about the Tarago, Yarra and Werribee river systems through each system's Environmental Water Advisory Group.

Who is engaged and how

Recreational users

Through formal advisory groups coordinated by Melbourne Water, representatives of recreational user groups are engaged. Advisory group members receive notifications about planned environmental water deliveries via the community bulletin.

For recreational users, safety related to higher water levels are a key concern.

On occasion, Melbourne Water informs recreational users directly about environmental watering (such as the Werribee fishing club or Canoes Victoria).

Environment groups

Representatives of environment groups are engaged through formal advisory groups coordinated by Melbourne Water. Advisory group members receive notifications about planned environmental water deliveries via the community bulletin.

Melbourne Water has informal relationships with various environment groups (such as Landcare, Birdlife Australia, Yarra Riverkeepers, Environment Victoria and Waterwatch) and meet with these groups on an as-needs basis.

Some groups, such as Waterwatch, share monitoring information with Melbourne Water.

Landholders/farmers

Through the Yarra Diversions newsletter, diversions licence holders receive information and updates on environmental watering.

Landholders and farmers are engaged through formal advisory groups coordinated by Melbourne Water. Advisory group members receive notifications about planned environmental water deliveries via the community bulletin.

Traditional Owners

Melbourne Water is doing a collaborative project with the Wurundjeri Tribe Land and Compensation Heritage Council and the Victorian Environmental Water Holder to document the Wurundjeri cultural values in the Yarra river system. The aim of this project is to increase understanding of values that can be supported with environmental water to achieve shared benefits for Aboriginal people from environmental watering (Aboriginal environmental outcomes).

Councils

Through formal advisory groups coordinated by Melbourne Water, Council representatives (from various local councils across region) are engaged. Advisory group members receive notifications about planned environmental water deliveries via the community bulletin.

Melbourne Water publishes an annual two-pager for each Council about activities undertaken in their catchment, including delivery of environmental flows.

General public

Melbourne Water communicates and engages with the general public through their website, media releases and Facebook and Twitter. Melbourne Water community bulletins are posted on their webpage, Facebook and Twitter, and issued to media contacts.