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The Macalister River flows from Mt Howitt in the Alpine National Park to join the Thomson River south of Maffra. It mostly flows through cleared floodplain that is used for dairy farming. Lake Glenmaggie is the single major storage and supplies water to the Macalister Irrigation District, with flows regulated at Maffra Weir. Environmental water is stored in Lake Glenmaggie.

Before Lake Glenmaggie was built, the Macalister River would regularly receive large floods in winter and spring. Although Lake Glenmaggie regularly spills, floods are now less common. A notable impact from irrigation and water harvesting is reversed seasonality of flows between Lake Glenmaggie and Maffra Weir, where higher-than-natural summer flows occur due to the delivery of irrigation water. In the same reach, flows are lower-than-natural in the water harvesting period in winter. Downstream of Maffra Weir most flows are diverted for irrigation in summer and autumn. The changed hydrology affects the migration of fish as well as the growth and dispersal of aquatic and riparian plants.

Maffra Weir prevents fish passage from upstream and downstream of the weir and the priority reach for fish migration flows is therefore reach 2 which is downstream of Maffra Weir to the confluence with the Thomson River. Non-fish objectives can be achieved in both reaches 1 and 2 (see below).

Storage manager
Environmental water holder

System map

Macalister 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 Macalister River

Fish icon
Protect and boost populations of native fish (including Australian grayling, tupong and Australian bass) prompting fish to move upstream and downstream and between the river and the ocean, and to spawn
Insect icon
Restore communities of waterbugs, which break down organic matter, provide a source of food for other animals and support the river’s food chain
Plant icon
Enable plants to germinate, establish and grow on the river bank

Environmental values

There are seven migratory native fish species in the Macalister River that move between freshwater and marine environments to complete their life cycle. These are the Australian grayling, short- and long-finned eel, tupong, Australian bass, short-headed lamprey and common galaxias.

Along the river banks there are some areas of dense woody riparian vegetation dominated by shrubs. Where livestock is excluded, vegetation is in good condition: elsewhere it is degraded. The non-woody plants that colonise the fringes of the river (such as reeds, sedges and rushes) have declined in recent years, as has in-stream vegetation. While the reason for the decline is uncertain, water turbidity, erosion and lack of flow variability are thought to have an effect.

Social and economic values

The Macalister Irrigation District is the major economic driver in the area and water from the Macalister system is highly valued by the local community. As a result, there is a genuine interest in the health of the Macalister River, particularly about water quality, erosion and vegetation condition. People also use the river for recreational fishing and bird watching. The waterways in the Macalister system (including the Macalister River) continue to hold significance for Traditional Owners. Waterways and wetlands in the region are important ceremonial places and for thousands of years the Macalister River has provided resources such as food and materials to the Gunaikurnai people.

Conditions mid-2016

In 2016–17 inflows to Lake Glenmaggie were lower than the average of the last 10 years. While this reduced the magnitude of spills that typically occur in winter and spring, water allocations were sufficient to provide most of the planned environmental watering.

Winter  low flows were delivered in July 2015 using carryover water from 2015–16. Spills from Lake Glenmaggie in July–August were managed by the storage manager, Southern Rural Water, to align with winter environmental flow recommendations. Multiple autumn freshes (small pulses of water), a winter fresh and winter low flows were delivered in April–June 2016.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Macalister River reaches 1 and 2

Autumn/winter baseflows (35–90 ML/day in May–July)

  • Provide habitat for waterbugs and for local movement of fish
  • Maintain water quality in pools and connectivity for platypus
  • Provide slow-moving water for submerged aquatic vegetation

Spring fresh (1,500 ML/day for 3–5 days in September–October)

  • Provide variability in water levels and wet the fringing woody vegetation

Macalister River reach 2

Autumn fresh (350 ML/day for 4–5 days in April–May)

  • Promote downstream migration and spawning of Australian grayling

Winter fresh (700 ML/day for 4–5 days in June–August)

  • Promote downstream migration and spawning of tupong and Australian bass

Spring/summer fresh (700 ML/day for 5 days in September–December)

  • Promote upstream migration opportunities for adults and juveniles of multiple fish species

Summer/autumn fresh (140 ML/day for 3 days in December–May)

  • Flush pools to maintain water quality for invertebrates
  • Provide water-level variability for emergent vegetation

Scenario planning

The highest priority in 2016–17 is to provide flows that prompt migration, breeding and recruitment (when animals survive to settlement or maturity) of native fish species that migrate between freshwater and estuarine environments, particularly the Australian grayling, Australian bass and tupong.

In drought conditions an autumn fresh (small pulses of water) will be provided for Australian grayling and a winter fresh will be provided for tupong, with any remaining water being utilised to continue winter base flows (or low flows). It's important to deliver a breeding flow for Australian grayling in a drought year because if conditions are dry a breeding flow may not be delivered in the Thomson River. This will also provide an opportunity to test if Australian grayling will successfully breed with a release of water from the Macalister alone.

Autumn flows also remain a high priority when conditions are dry because these are the most impacted flows in reach 2, where most water is diverted for irrigation.

As water availability increases in dry and average conditions, spring and summer freshes will be delivered. The highest-priority spring freshes will provide a cue for juvenile Australian grayling, tupong, adult eels and short-headed lampreys to return upstream from estuarine and marine habitats.

In a wet year water will be available to provide summer freshes that provide connectivity all the way through reach 2. It will also be possible to increase the duration of some releases in line with wet-season flow recommendations.

Carryover of some water into July 2017 is a high priority under all conditions to provide baseflows through reaches 1 and 2 outside the irrigation season.

Table 2 Potential environmental watering for the Macalister system under a range of planning scenarios

Planning scenario

Drought

Dry

Average

Wet

Expected river conditions

  • No unregulated flows
  • Passing flows at Maffra Weir reduced
  • Possible spills from Lake Glenmaggie in spring, minor flood levels may occur
  • Passing flows at Maffra Weir may be reduced
  • Regular spills from Lake Glenmaggie in spring, minor flood levels may occur
  • Passing flows at Maffra Weir may be reduced, with savings accrued in summer for use in autumn
  • Large and frequent spills from Lake Glenmaggie, moderate to major flood levels may occur
  • Passing flows at Maffra Weir may be reduced, with savings accrued in summer for use in autumn

Expected availability of environmental water

  • 9,400 ML
  • 13,000 ML
  • 14,400 ML
  • 22,600 ML

Potential environmental watering – tier 1 (high priorities)

  • One autumn fresh
  • One winter fresh
  • Autumn/winter baseflows
  • One autumn fresh
  • One winter fresh
  • One spring fresh
  • Autumn/winter baseflows
  • One autumn fresh
  • One winter fresh
  • One spring fresh
  • Autumn/winter baseflows
  • One autumn fresh
  • One winter fresh
  • One spring fresh
  • One summer fresh
  • Autumn/winter baseflows

Potential environmental watering – tier 2 (additional priorities)

  • One spring fresh
  • One summer fresh
  • Increase duration of winter baseflow
  • One summer fresh
  • Increase magnitude of spring fresh
  • One summer fresh
Increase duration of spring fresh

Possible volume of environmental water required to meet objectives1

  • 9,400 ML (tier 1)
  • 4,600 ML (tier 2)
  • 13,000 ML (tier 1)
  • 1,700 ML (tier 2)
  • 13,400 ML (tier 1)
  • 4,200 ML (tier 2)
  • 18,000 ML (tier 1)
  • 2,900 ML (tier 2)

Priority carryover requirements

  • 1,000 to 1,200 ML

1 Environmental water requirements for tier 2 actions are additional to tier 1 requirements.

Risk management

In preparing its seasonal watering proposal, West Gippsland Catchment Management Authority considered and assessed risks, and identified mitigating strategies, relating to implementing environmental watering. Risks and mitigating actions are continually reassessed by program partners 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 West Gippsland region communities are involved in decisions about the Thomson and Macalister river systems and the Lower Latrobe wetlands. The community is engaged informally and through the Macalister river Project Advisory Group.

Who is engaged and how

Recreational users

A representative of VRFish sits on the Macalister river Project Advisory Group.

West Gippsland Catchment Management Authority engages with Field & Game Australia when developing the Lower Latrobe wetlands seasonal watering proposal (annual scoping). Field & Game Australia shares wetland bird count data with the Catchment Management Authority which helps with reporting on environmental watering outcomes.

The Catchment Management Authority notifies many recreational user groups about environmental water deliveries. These groups include canoe clubs, outdoor education companies and school groups (many of whom come from outside of the region). These groups are interested in managing safety and also achieving opportunities for shared benefits from environmental watering (e.g. kayaking on higher flows in the Thomson river).

Environment groups

Representatives from environment groups (Environment Victoria, Landcare and Native Fish Australia) sit on the Macalister river Project Advisory Group.

Irrigators/farmers

Irrigation representatives sit on the Macalister river Macalister river Project Advisory Group.

Southern Rural Water sends environmental water delivery notifications to their irrigation customers on behalf of the Catchment Management Authority. These irrigation customers are often primarily interested in environmental watering from a safety and infrastructure protection perspective.

Traditional owners

Through the Catchment Management Authority Indigenous facilitator, the Gunaikurnai Land and Waters Aboriginal Corporation has been invited to join the Macalister river Project Advisory Group.

The Catchment Management Authority and Gunaikurnai Land and Waters Aboriginal Corporation have a Memorandum of Understanding. The Catchment Management Authority recognises the recently developed Gunaikurnai Land and Waters Aboriginal Corporation draft Whole Of Country Plan which contains aspirations for rivers and wetlands in Gippsland.

Councils

The Wellington Shire Council is a member of the Macalister river Macalister river Project Advisory Group.

The Wellington Shire Council, the Latrobe City Council and the Baw Baw Shire Council are all on the Southern Rural Water environmental water delivery notification list.

General public

Public signage informing the general public about upcoming environmental water deliveries is set up a few days before a planned delivery along key recreational sites in the upper Thomson River. This is for primarily for public safety purposes.