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The ecology of the Hattah Lakes and surrounding floodplain is strongly influenced by flooding regimes of the Murray River. The system fills when there is high flow in the Murray River, and some lakes hold water for several years after floods recede. Regulation of the Murray River has significantly reduced the frequency and duration of small- to medium-sized natural floods in the Hattah Lakes system. Over time, this has degraded vegetation communities and reduced the diversity and abundance of animals that use the vegetation and wetlands for habitat and food.

The Hattah Lakes complex can be broadly divided into the southern Hattah Lakes, which contains permanent to semi- permanent wetlands, and the higher-elevation northern Hattah Lakes, which are mostly ephemeral wetlands.

The Messenger, Oateys and Cantala regulators allow water to flow between the Murray River and Hattah Lakes. When flows in the Murray River are about 26,000 ML per day, water begins to flow through Messengers regulator into Chalka Creek and through to the Hattah Lakes complex. A permanent pump station can deliver up to 1,000 ML per day to the southern Hattah Lakes through Chalka Creek. The regulators and pump station are used in combination with several small constructed levees to restore a beneficial pattern of flooding to the lakes system. Lake Kramen is in the south-east area of Hattah-Kulkyne National Park and disconnected from the main Hattah Lakes complex, but the Hattah Lakes pump station can deliver up to 145 ML per day to Lake Kramen to restore flooding regimes.

Current infrastructure enables environmental flows to the southern Hattah Lakes and Lake Kramen. Future infrastructure being built under the Victorian Murray Floodplain Restoration Project will allow water to reach additional wetlands and the floodplain in the northern Hattah Lakes.

Traditional Owners

System map

Environmental watering objectives in the Hattah Lakes

icon-objectives-fish
Increase the native fish populations
Plant icon
Restore and maintain a mosaic of healthy wetland and floodplain plant communities
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Provide feeding and nesting habitat for the successful recruitment of waterbirds and woodland birds

Environmental values

Hattah Lakes is home to a diverse range of flood-dependent vegetation that changes with the topography of the landscape. Vegetation types range from wetland communities in lower-lying areas that require almost annual flooding to lignum and black box communities situated higher on the floodplain that only need flooding once every four to five years (on average).

A combination of natural flooding and the delivery of environmental flows since 2010 has improved tree canopy health and recruitment of black box and river red gum communities throughout the Hattah Lakes. Woodland birds, including the endangered regent parrot, have benefitted from the improved tree health.

Hattah Lakes provides important waterbird breeding sites in an arid landscape. A total of 34 species of waterbirds are known to breed at the lakes when conditions are suitable. Another six species of waterbirds breed in the surrounding floodplain. Wetland drought refuge sites are limited in the region, making Hattah Lakes critically important for water-dependant flora, waterbirds and terrestrial animals.

The Hattah Lakes support large-bodied native fish species (such as golden perch) and small-bodied wetland species (such as carp gudgeon). Fish move between the lakes and the Murray River when flows are suitable and also persist in wetlands that retain water in the Hattah Lakes during dry years before dispersing again during flooding.

Traditional Owner cultural values and uses

The Hattah Lakes system is part of a highly sensitive region for Aboriginal cultural values and lies on the border of two documented language groups, the Latji Latji and the Jari Jari. More than 1,000 Indigenous archaeological sites at the Hattah Lakes are registered with Aboriginal Victoria, with the freshwater lakes and wetlands providing focal points for trade and cultural exchanges amongst the region’s Traditional Owners. The local Aboriginal community maintains strong connections to the land and its resources such as native species used for food and medicine.

Mallee CMA has sought the input of Aboriginal Elders and members of the Aboriginal community who have expressed their connection with the Hattah Lakes area to environmental water planning.

Mallee CMA held on-Country meetings and discussions with Elders and community members to explore their interests and aspirations for the Hattah Lakes region. Themes raised included:

  • areas where environmental flows are planned to take place in 2021-22 and the quantity of water that will be delivered
  • areas that Aboriginal Elders and other participants believe require water (such as black box in the northern part of Hattah- Kulkyne National Park)
  • dying gum trees and black box, and future work that may assist with the delivery of water to these affected trees
  • the protection of known burial sites by Parks Victoria Cultural Heritage rangers near Lake Mournpall in the Hattah Lakes system.

Social, recreational and economic values and uses

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

  • water-based recreation (such as fishing, kayaking and swimming)
  • riverside recreation and amenity (such as birdwatching, camping, photography and walking)
  • community events and tourism (such as ‘Junior Ranger’ school holiday programs including bushwalking, birdwatching and bug hunting, school education programs and tours involving kayaking, bike riding and camping)
  • socio-economic benefits (such as bee keeping, connecting with nature, ecotourism and social gatherings).

Recent conditions

Rainfall and temperatures in the Hattah Lakes region during 2021-22 were close to the long-term average. Victorian Murray allocations reached 55 percent of high-reliability water shares by mid-October and 100 percent by February 2021. Allocations and return flows from other environmental deliveries in upstream Goulburn and Murray river systems provided sufficient supply to achieve environmental watering requirements at Hattah Lakes during 2020-21.

High rainfall in the upper Murray River catchment and a large release of water for the environment to the Murray River resulted in flows of more than 15,000 ML per day in the Murray River at Robinvale on several occasions between July and November 2020, but these were well below the 26,000 ML per day flow that is needed for natural inflows to the Hattah Lakes. The river’s flow gradually receded during summer and autumn to operational levels of between 5,000 to 11,000 ML per day.

The Hattah Lakes filled when water for the environment was delivered to them in 2017 and held water until February 2020. Lake Kramen was filled with water for the environment in spring 2019 and still retains some water.

Deliveries of water for the environment to the Hattah Lakes commenced again in May 2021. About 30,000 ML of water for the environment was pumped into the Hattah Lakes between May and June 2021 to fill low-lying wetlands to improve the condition of trees, stimulate the growth of aquatic plants, support carbon and nutrient cycles and provide food and habitat for waterbirds. Depending on climatic conditions and water availability, this watering event will be extended into winter and spring 2021, to inundate more wetlands to a greater depth to increase outcomes for various vegetation communities, waterbirds and native fish.

Scope of environmental watering

Table 1 Potential environmental watering actions, expected watering effects and associated environmental objectives for the Hattah Lakes

Potential environmental watering action1

Expected watering effects

Environmental objectives

Southern Hattah Lakes (top-up and fill of selected wetlands and lower floodplain during spring 2021)

  • Stimulate the growth and improve the condition of river red gums fringing wetlands and on the lower floodplain
  • Provide breeding habitat for waterbirds
  • Stimulate new growth of aquatic vegetation
  • Inundate dry wetlands to release carbon and nutrients to increase food web productivity
  • Provide spawning and recruitment habitat for small-bodied native fish

Fish iconPlant iconHeron iconConnected icon

Hattah Lakes (floodplain inundation up to 45 m Australian Height Datum (AHD) at any time if there is a natural flood)

  • Wet river red gums and black box on the floodplain to stimulate growth and improve the condition of mature trees
  • Provide suitable soil conditions for the germination of black box trees on the floodplain and support the survival and growth of trees that germinated in 2017
  • Provide suitable conditions to support waterbird breeding and feeding
  • Provide connections to allow native fish to move between Hattah Lakes and the Murray River
  • Provide spawning and recruitment habitat for small-bodied native fish and nursery habitat for large-bodied native fish (such as golden perch)
  • Inundate dry wetlands to release carbon and nutrients to increase food web productivity

Fish iconPlant iconHeron iconConnected icon

1The Hattah Lakes pump station may also be operated at any time of year for annual maintenance requirements.

Engagement

Table 2 shows the partners and stakeholder organisations who have assisted the Mallee CMA prepare the Hattah Lakes seasonal watering proposal.

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 Mallee Regional Catchment Strategy and the Mallee Waterway Strategy.

Table 2 Partners and stakeholders engaged in developing the Hattah Lakes seasonal watering proposal

Partner and stakeholder engagement
  • Local Landcare groups
  • Mid-Murray Field Naturalists
  • Commonwealth Environmental Water Office
  • Murray-Darling Basin Authority (the Living Murray program)
  • Parks Victoria
  • Goulburn-Murray Water
  • Department of Environment Land, Water and Planning (Fire Forest and Regions)
  • Department of Environment Land, Water and Planning (Water and Catchments)
  • Mildura Rural City Council
  • Landholders and farmers who live around the Hattah Lakes
  • Hattah Store owners
  • Mallee Tours
  • Murray Offroad Adventures
  • Mildura Information Centre
  • Visit Mildura
  • Wild Side Outdoors
  • Sunrasia Apiarist Association
  • Birdlife Mildura
  • Sunraysia Bushwalkers
  • Four-wheel drive club
  • Mallee CMA Land and Water Advisory Committee
  • CollaborateTraditional Owners of Hattah Lake (Aboriginal Victorians from Wadi Wadi, Tati Tati, Latje Latje and Munutunga)

Page last updated: 22/07/21