Skip to content

The Wimmera River starts in the Pyrenees Range near Elmhurst and flows through Horsham, Dimboola and Jeparit before terminating at Lake Hindmarsh, which is Victoria's largest freshwater lake. The Wimmera receives flows from several regulated tributaries including the MacKenzie River and the Mount William and Burnt creeks. All these tributaries, Bungalally Creek and the Wimmera River downstream of Mount William Creek can receive environmental water. In exceptionally wet periods, Lake Hindmarsh may overflow into Outlet Creek and on to Lake Albacutya, an internationally recognised Ramsar-listed wetland.

Water in the Wimmera system is stored in three on-stream reservoirs — Lake Wartook on the MacKenzie River, Lake Lonsdale on Mount William Creek and Lake Bellfield on Fyans Creek — and in several off-stream storages — Taylors Lake, Lake Fyans and Toolondo Reservoir. A channel system enables water to be transferred between several storages. Water can also be transferred from the Glenelg system to the Wimmera system from Rocklands Reservoir via the Rocklands–Toolondo Channel and from Moora Moora Reservoir via the Moora Channel. The connected storages and channels are collectively called the Wimmera–Glenelg Headworks System and harvested water is also used for towns and stock and domestic supply throughout the Wimmera catchment and parts of the Avoca, Hopkins, Loddon, Glenelg and Mallee catchments. Passing flows are provided to the Wimmera River and to lower Mount William and Fyans creeks.

Priority reaches for environmental watering in the Wimmera system are the Wimmera River reach 4, MacKenzie River reaches 2 and 3, upper and lower Mount William Creek, upper and lower Burnt Creek and Bungalally Creek.

Yarriambiack Creek is a distributary of the upper Wimmera River that naturally would have received some flows during high-flow events. However, the creek now receives more flows due to modifications to the offtake. This affects environmental water deliveries to the high-priority reaches of the Wimmera River. In line with past practice during dry years, flows entering the creek may be blocked to ensure watering objectives in the Wimmera River are not compromised.

Storage manager
Environmental water holder

System map

Wimmera System
Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches represent potential watering sites.

Environmental watering objectives in the Wimmera system

Fish icon
Rehabilitate and protect populations of native fish including one of Victoria’s few selfsustaining populations of freshwater catfish
Water icon
Maintain water quality to provide suitable conditions for fish and other water-dependent plants and animals
Platypus icon
Increase platypus populations by increasing the quality and quantity of habitat and food and providing suitable conditions for breeding and dispersal
Plant icon
Improve the condition, abundance and diversity of aquatic, emergent and riparian vegetation
Insect icon
Increase the abundance and diversity of waterbugs which provide energy, break down dead organic matter and support the waterway’s food chain

Environmental values

The Wimmera system is home to many significant plant and animal species including populations of freshwater catfish, flat-headed gudgeon, carp gudgeon, river blackfish, southern pygmy perch, Australian smelt and Wimmera bottlebrush.

The Wimmera River itself supports abundant native fish, waterbird, turtle, frog and native water rat populations and one of Victoria's few self-sustaining populations of freshwater catfish.

The MacKenzie River contains the only stable population of platypus in the Wimmera and supports good populations of native fish including river blackfish, waterbugs, threatened Glenelg spiny crayfish and turtles. During dry periods, the middle and upper reaches of the MacKenzie River maintain regular flow and provide refuge for these populations.

The vegetation along Burnt and Bungalally creeks provide habitat corridors and upper Burnt Creek contains an important native fish community and a population of threatened western swamp crayfish. Mount William Creek supports regionally important populations of river blackfish, southern pygmy perch and threatened western swamp crayfish.

Social, cultural and economic values

The Wimmera system offers many popular recreational activities including walking, boating, rowing, waterskiing, fishing and camping, and it provides important amenity for Wimmera residents. Events held on the waterways include waterskiing at the annual Kanamaroo Festival, the Horsham Triathlon, the Dimboola Regatta and Head of the Wimmera rowing event and fishing competitions in Horsham, Jeparit and Dimboola. The waterways in the Wimmera system continue to hold significance for Traditional Owners and their Nations in the region including those represented by the Barengi Gadjin Land Council.

Conditions mid-2017

Heavy rainfall in winter/spring 2016 ended a prolonged dry period in the Wimmera catchment. Unregulated natural flows and passing flows met a high proportion of planned winter and spring watering actions. Passing flows from Lake Lonsdale were suspended for much of winter/spring to reduce the flood risk associated with the natural high flows through the system and to help storage management operations. Managed environmental water releases in 2016–17 were mainly used to provide low flows and freshes during summer and autumn. With the high rainfall, allocations reached 100 percent in October 2016 for the first time since 2011–12. In April 2017, the CEWH received its first allocation of 15 percent.

The wet conditions in 2016 and environmental water deliveries have improved the condition of the rivers and creeks in the Wimmera system. Monitoring from 2016–17 shows that native fish numbers are increasing and the MacKenzie River platypus populations are continuing to breed.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Wimmera River (reach 4)

Summer/autumn low flows (15 ML/day or natural in December–May)1

  • Maintain in-stream habitat to support native fish populations and waterbugs
  • Maintain near-permanent inundation of the stream channel for riparian vegetation and to prevent the growth of terrestrial plants in the streambed

Winter/spring low flows (30 ML/day in June–November)

  • Provide variability in flows to maintain various types of habitat

Summer/autumn freshes (1–3 freshes of 70 ML/day for 2–7 days in December–May)

  • Flush pools to improve water quality and maintain habitat for fish and waterbugs
  • Provide fish passage to allow fish to move through the reach

Winter/spring freshes (1–5 freshes of 70 ML/day for 1–4 days in June–November)

  • Provide fish passage to allow fish to move through the reach and increase the flow to stimulate their movement
  • Maintain water quality to support fish populations

Winter/spring freshes (1–3 freshes of 200 ML/day for 1–3 days in June–November2)

  • Wet lower benches, moving organic debris and promoting habitat diversity

Winter/spring freshes (1–2 freshes of up to 1,300 ML/day for 2–3 days in June–November)

  • Flush surface sediments from hard substrates to improve habitat quality and support waterbugs
  • Wet higher benches, moving organic debris and promoting diverse habitat
  • Maintain the quality, diversity and extent of submerged and emergent aquatic vegetation for fish habitat

MacKenzie River (reach 2 and 3)

Year-round low flows (of 2–27 ML/day or natural, year-round)1

  • Maintain edge habitats and deeper pools and runs for waterbugs
  • Maintain near-permanent inundation of the stream channel for riparian vegetation and to prevent the growth of terrestrial plants including the Wimmera bottlebrush in the streambed and aquatic vegetation for fish habitat
  • Maintain a sufficient area of pool habitat for native fish populations
  • Facilitate the annual dispersal of juvenile platypus into the Wimmera River

Summer/autumn freshes (3–4 freshes of 5–50 ML/day for 2–7 days each in December–May)

  • Provide variable flows during the low-flow season for waterbugs, fish movement and maintenance of water quality and habitat diversity

Winter/spring freshes (5 freshes of 35–55 ML/day for 2–7 days in June–November)

  • Stimulate fish movement and maintain water quality and habitat diversity

Winter/spring freshes (1–5 freshes of up to 130–190 ML/day for 1–4 days in June–
November)

  • Maintain edge habitats and shallow water habitat for waterbugs
  • Maintain inundation of the stream channel to protect riparian vegetation and prevent excessive streambed colonisation by terrestrial vegetation species
  • Maintain a sufficient area of pool habitat for native fish populations

Burnt Creek

Year-round low flows targeting upper Burnt Creek (1 ML/day or natural, year-round)1

  • Maintain edge habitats and shallow water habitat for waterbugs
  • Maintain inundation of the stream channel to protect riparian vegetation and prevent excessive streambed colonisation by terrestrial vegetation species
  • Maintain a sufficient area of pool habitat for native fish populations

Summer/autumn freshes targeting upper Burnt Creek (3 freshes of 30 ML/day for 2–7 days each in December–May)

  • Prevent the decline in water quality by flushing pools during low flows

Winter/spring freshes targeting upper Burnt Creek (1–5 freshes of 55 ML/day for 3–7 days in June–November)

  • Allow fish to move throughout the reach
  • Flush sediments from hard substrates to increase biofilm production and food for waterbugs
Winter/spring freshes targeting upper Burnt Creek (1–3 freshes of up to 160 ML/day for 1–3 days in June–November)
  • Disturb biofilms present on rocks or woody debris to stimulate new growth and provide food for waterbugs

Year-round fresh targeting lower Burnt Creek (1 fresh of 45 ML/day or natural for 2 days at any time)

  • Inundate riparian vegetation to maintain its condition and facilitate recruitment
  • Move organic debris in the channel to support waterbugs
  • Maintain the structural integrity of channels

Mount William Creek

Top-up of upper Mount William Creek pools

  • Maintain habitat for native fish and waterbugs

Year-round low flows targeting lower Mount William Creek (5 ML/day or natural, year-round) 1

  • Maintain edge habitats and shallow water habitat for waterbugs and endemic fish
  • Maintain near-permanent inundation of the stream channel for riparianvegetation and to prevent the growth of terrestrial plants in the streambed
Summer/autumn freshes targeting lower Mount William Creek (3 freshes of 20–30 ML/day for 2–7 days in December–May)
  • Prevent a decline in water quality by flushing pools during low flows
  • Provide variable flows during the low-flow season for waterbugs, for fish movement and to maintain water quality and diversity of habitat

Winter/spring freshes targeting lower Mount William Creek (1–5 freshes of up to 100 ML/day for 1–7 days in June–November)

  • Wet benches, move organic debris and promote habitat diversity
  • Flush surface sediments from hard substrates to support waterbugs

Mount William Creek 

Winter/spring freshes targeting lower Mount William Creek (1–3 freshes of up to 500 ML/day for 1–3 days in June–November)
  • Wet the highest benches, move organic debris and promote habitat diversity

Bungalally Creek

Year-round fresh (1 fresh of 60 ML/day for 2 days at any time)

  • Inundate the riparian zone to maintain its condition and facilitate recruitment for riparian vegetation communities
  • Maintain the structural integrity of the channel and prevent loss of channel
    capacity

1 Cease-to-flow events occur naturally in the Wimmera system and may be actively managed. In the most recent flow study, the recommendation is that cease-to-flow events should occur as infrequently as possible and not exceed the duration of events that might have occurred naturally, to reduce stress on environmental values. Cease-to-flow events should be followed with a fresh lasting at least seven days.

2 Dependent on catchment conditions, the timing of this fresh may vary to optimise environmental outcomes.

Risk management

In preparing its seasonal watering proposal, Wimmera 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

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.

In the Wimmera region communities are involved in decisions about the Wimmera and MacKenzie rivers, Mount William creek, Burnt creek, Bungallaly creek and some of the wetlands on the Wimmera-Mallee pipeline. This happens through direct engagement on an as needed, issues basis.

Who is engaged and how

Recreational users

Recreational user representatives are engaged by the Wimmera Catchment Management Authority through direct engagement on an issues basis. During drought periods in particular, the Catchment Management Authority holds meetings with recreational user groups. Recreational users are updated on planned environmental water deliveries. The Catchment Management Authority also regularly engages with recreational users through Facebook, web, SMS and media releases.

Environment groups

The main way that environmental groups are engaged on environmental watering is through opportunistic Catchment Management Authority attendance at Yarriambiack Creek Advisory Committee meetings. A Catchment Management Authority representative provides updates on environmental water scoping and delivery at these meetings. Meetings with other environmental groups are on an as needs basis.

An environmental advocate sits on the Catchment Management Authority rivers and streams advisory committee (which is engaged on natural resources management matters more broadly).

Landholders/farmers

Landholders are updated by the Catchment Management Authority on environmental water planning (scoping) and delivery. Landholders are notified by phone calls and emails and SMS during the delivery phase.

Landholders provide feedback on the outcomes of environmental watering such as photographs and observations of birds and frogs. The Catchment Management Authority attends relevant community events (including Wimmera Machinery Field Days) to raise awareness about the benefits of environmental watering.

Landholders sit on the Catchment Management Authority rivers and streams advisory committee (which is engaged on natural resources management matters more broadly).

Traditional Owners

The Barengi Gadjin Local Land Council has participated in the development of the Catchment Management Authority regional waterway strategy. These strategies identify the rivers and wetlands of the highest environmental, social, cultural and economic values in the Wimmera region.

The Catchment Management Authority and the Land Council meet on a regular basis to discuss natural resource management matters more broadly.

Councils

Horsham and Hindmarsh Councils are regularly engaged by the Catchment Management Authority. As these two Councils are the managers of weirs from which environmental water is managed, the Catchment Management Authority discusses planned environmental watering with them to assist weir management (specifically to assist aims of reducing water losses and achieving 'shared benefits' such as timing environmental watering around community events). Northern Grampians Council and Yarriambiack Council are also engaged on environmental watering on an as-needs basis.

General public

The Catchment Management Authority engages with the general public on environmental watering via SMS, their website, Facebook, and media releases.

The Catchment Management Authority conducted a community survey on waterway values and observations related to environmental watering.