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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 contain 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 the 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 is disconnected from the main Hattah Lakes complex. The Hattah Lakes pump station can deliver up to 145 ML per day to Lake Kramen. The new infrastructure being built under the Victorian Murray Floodplain Restoration Project (VMFRP) will allow water to reach additional wetlands and floodplain areas in the northern Hattah Lakes.

Traditional Owners

System map

Environmental watering objectives in the Hattah Lakes

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Maintain populations of small-bodied and large-bodied native fish at the Hattah Lakes
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By 2030, improve the function of water-dependent ecosystems by improving productivity linkages between the river and floodplain/wetland habitats
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Improve the species richness and abundance of native water-dependent floodplain and wetland aquatic vegetation by 2030

Maintain the extent and improve the condition of river red gum, black box and lignum, compared to 2006 baseline levels by 2030
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Maintain and/or increase the regional waterbird population by providing conditions for breeding and fledging at least three times every 10 years

Maintain and/or increase the regional waterbird population by providing refuge during droughts
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Maintain a variety of freshwater ecosystem types within the Hattah Lakes Icon Site, including semi-permanent lakes, persistent temporary wetlands, floodplain woodlands, shrublands and episodic wetlands

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 the Hattah Lakes critically important for water-dependent flora, waterbirds and terrestrial animals during dry periods.

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. Groups which have an interest in Hattah Lakes include Latji Latji Mumthelang, Tati Tati, Culpra-Millee, Nyeri Nyeri and Munatunga Elders.

More than 1,000 Aboriginal 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 among the region’s Traditional Owners. Local Aboriginal communities maintain strong connections to the land and its resources, such as native species used for food and medicine.

Although COVID-19 restrictions limited opportunities for large on-Country meetings, several face-to-face meetings were held in early 2022 to discuss plans for water for the environment in the Hattah Lakes area. Mallee CMA met with Latji Latji Mumthelang and representatives from Munatunga and Culpra Millee. Traditional Owner groups invited to discussions included Tati Tati and Nyeri Nyeri.

Tati Tati wish to express their lack of representation in no way is a reflection their lack of interest or cultural responsibility in caring for wetlands on Tati Tati Country. It does, however, reflect Tati Tati’s deliberate shift to only engaging organisations that demonstrate a commitment to upholding cultural safety. Tati Tati will continue to look to the future to partner with organisations transitioning to First Nations empowerment – not engagement.

Discussions covered the planning of water for the environment and interests and aspirations for the Hattah Lakes region. Themes raised during discussions included:

  • areas where environmental flows are planned to take place in 2022-23 and the quantity of water that will be delivered
  • areas that Aboriginal Elders and other participants believe require water (such as Chalka Creek, as it is very dry in this area, and Lake Kramen, although historically this lake has dried out temporarily)
  • projects underway that include constructing a levee to allow water to be delivered into the floodplain north of the current area of delivery as part of the VMFRP.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 5.2.12, 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 run by Parks Victoria, including bushwalking, birdwatching and bug hunting; local school education programs; Melbourne-based schools’ educational excursions; and tours involving kayaking, bike riding and camping)
  • socio-economic benefits (such as commercial beekeepers who rest bees away from horticultural orchards in native flowering trees around the lake, multiple ecotourism operators who benefit directly when the lakes contain water, social wellbeing from connecting with nature, and social gatherings).

Recent conditions

Between July 2021 and March 2022, the temperature and rainfall in the vicinity of the Hattah Lakes were above average.

In 2021-22, allocations against high-reliability water shares reached 52 percent in August and 100 percent in October. Low- reliability water shares began receiving allocations in December and reached their full allocations in February. This is the first time Murray seasonal determinations reached maximum availability since the introduction of the current entitlement products in 2007. Spills from Hume Dam resulted in the deduction of most spillable carryover from 2020-21. Section 5.2 has more information about the resource position of water for the environment in the Victorian Murray system during 2021-22.

While the Hattah Lakes can receive minor inflows after heavy local rainfall, the hydrology is mainly affected by large flows in the Murray River that spill into the lakes and by deliveries of water for the environment.

The southern Hattah Lakes were partially filled with water for the environment in May and June 2021 after a two-year drying period. Unregulated flows in the Murray River in October and November 2021 exceeded the minimum commence-to-flow level into the Hattah Lakes, but they were lower than the water levels in the lakes at the time. The regulators in Chalka Creek were kept closed to prevent existing water from flowing out of the lakes, and the Hattah pumps were used to deliver some of the Murray River flows into the lakes.

Deliveries of water for the environment for the Hattah Lakes were managed in line with an average climate scenario during 2021-22, and all the planned actions were fully achieved. The lakes are only managed in line with a wet climate scenario in years when the Murray River floods and causes widespread inundation of the Hattah Lakes system.

More than 46,000 ML of water for the environment was delivered to the southern Hattah Lakes during October and November 2021, inundating 17 lakes and low-lying parts of the surrounding floodplain. Water levels drew down over summer and autumn through a combination of active releases, seepage and evaporation. About 15,000 ML of water for the environment drained from the Hattah Lakes back into the Murray River from December 2021 to March 2022, carrying carbon, nutrients and organisms that can support riverine food webs. Water that returned to the Murray River was subsequently used for environmental flows at downstream sites in South Australia.

Lake Kramen is a periodically inundated (episodic) wetland, separate from the main Hattah Lakes, that requires filling on average once every eight years. It last filled in 2019 and dried during 2021-22. No active watering is planned at Lake Kramen for at least four years to allow lake-bed herbaceous plants to grow and complete their life cycles.

The influence of La Niña (although weakening) remained steady over south-eastern Australia during autumn 2022 and continues to influence the climate outlook. This climate feature, combined with the prospect of high water availability in 2022- 23, may trigger additional deliveries of water for the environment in 2022-23 to build on environmental outcomes achieved in 2021-22.

Scope of environmental watering

Table 5.2.12 describes the potential environmental watering actions in 2022-23, their expected watering effects (that is, the intended physical or biological effects of the watering action) and the longer-term environmental objectives they support. Each environmental objective relies on one or more potential environmental watering actions and their associated physical or biological effects.

Table 5.2.12 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 selected wetlands between  42.5 m and 43.5 m AHD and lower floodplain during winter/spring 2022)

  • Stimulate the growth and improve the condition of river red gums fringing wetlands and (when filled to 43.5 m AHD) on the lower floodplain
  • Provide conditions for lake-bed herbaceous plants to grow during the drawdown phase following watering
  • Provide breeding and feeding habitat for waterbirds
  • Stimulate new growth of aquatic vegetation
  • Inundate dry wetlands to release carbon and nutrients to increase food web productivity
  • Increase productivity in the Murray River downstream of the Hattah Lakes through the provision of return flows (when filled to 43.5 m AHD)
  • Provide connections between the floodplain and the Murray River to allow the exchange of nutrients, carbon, fish and plant propagules
  • Provide spawning and recruitment habitat for small-bodied native fish and nursery habitat for large-bodied native fish (such as golden perch)
  • Inundate a variety of wetland types at different elevations across the Hattah Lakes to increase habitat diversity

Fish iconPlant iconHeron iconConnected iconMountain Stream icon

Southern Hattah Lakes (top up and fill selected wetlands and lower floodplain to 43.5 m AHD at any time following a natural flood)

  • Stimulate the growth and improve the condition of river red gums fringing wetlands and (when filled to 43.5 m AHD) on the lower floodplain
  • Provide conditions for lake-bed herbaceous plants to grow during the drawdown phase following watering
  • Provide breeding and feeding habitat for waterbirds
  • Stimulate new growth of aquatic vegetation
  • Inundate dry wetlands to release carbon and nutrients to increase food web productivity
  • Increase productivity in the Murray River downstream of the Hattah Lakes through the provision of return flows (when filled to 43.5 m AHD)
  • Provide connections between the floodplain and the Murray River to allow the exchange of nutrients, carbon, fish and plant propagules
  • Provide spawning and recruitment habitat for small-bodied native fish and nursery habitat for large-bodied native fish (such as golden perch)
  • Inundate a variety of wetland types at different elevations across the Hattah Lakes to increase habitat diversity

Fish iconPlant iconHeron iconConnected iconMountain Stream icon

1In consultation with the VEWH, Mallee CMA and Parks Victoria, the Hattah Lakes pump station may be operated at any time of year by Goulburn-Murray Water for testing, pump maintenance and repairs.

Scenario planning

Table 5.2.13 outlines potential environmental watering and expected water use under a range of planning scenarios.

In 2022-23, deliveries of water for the environment are planned for the Hattah Lakes under all climate scenarios except for drought.

Under a wet climate scenario, natural floods are expected to inundate large parts of the Hattah Lakes. If only minor or moderate flooding occurs, water for the environment may be pumped into the lakes to achieve the target water level of 43.5 m AHD to inundate floodplain habitats.

In the absence of a natural flood in winter or early spring, the Hattah pumps will be used to refill the lakes and low-lying areas of the floodplain that were watered in autumn and spring of 2021. The proposed delivery of 35,000 ML of water for the environment under an average scenario (providing inundation to 43.5 m AHD) will provide consecutive years of high-level inundation of the Hattah Lakes to consolidate and build on environmental outcomes from watering in 2021-22.

The level of watering will likely vary between a dry and average climate scenario to mimic natural variations in water levels associated with each scenario. Up to 15,000 ML of water for the environment will be delivered under a dry climate scenario to top up the semi-permanent wetlands within the southern Hattah Lakes system to 42.5 m AHD. Up to 35,000 ML will potentially be delivered under an average climate scenario to inundate semi-permanent wetlands in low-lying areas as well as some temporary wetlands at slightly higher elevations.

No active watering is proposed under a drought scenario. The water delivered to the Hattah Lakes in spring 2021 will likely persist in some wetlands throughout 2022-23 without additional water, and it will provide refuge habitat for waterbirds and fish that moved into the Hattah Lakes during the deliveries in 2021. There is little value in trying to deliver extra water to trigger plant and animal growth and reproduction during drought conditions because there may not be sufficient resources within the landscape to sustain new life.

It is envisaged that during 2023-24, Hattah Lakes will enter a drawdown phase, and there is currently no requirement for high- priority carryover under any climate scenario.

Planning scenario table

Table 5.2.13 Potential environmental watering for the Hattah Lakes under a range of planning scenarios

Planning scenario

Drought

Dry

Average

Wet

Expected river conditions

  • Low flow year- round in the Murray River and no natural inflow to the Hattah Lakes; substantial wetland drying will occur
  • Rare high-flow events in the Murray River and no natural inflow to the Hattah Lakes
  • Short periods of high flow in the Murray River with minor spills from storages, most likely in late winter/ spring, providing minor natural inflow to the Hattah Lakes
  • Lengthy periods of high flow in the Murray River with major spills from storages resulting in widespread wetting of the Hattah Lakes and floodplain

Potential environmental watering – tier 1 (high priorities)

  • N/A
  • Southern Hattah Lakes spring top up and fill to 42.5 m AHD targeting semi-permanent1wetlands
  • Southern Hattah Lakes spring top up and fill to 43.5 m AHD targeting semi-permanent1 wetlands, temporary2 wetlands and low- level floodplain inundation
  • Southern Hattah Lakes top up and fill to 43.5 m AHD at any time targeting semi- permanent1 wetlands, temporary2 wetlands and low- level floodplain inundation

Possible volume of water for the

environment required to achieve objectives

  • N/A
  • 15,000 ML
  • 35,000 ML
  • 0-35,000 ML

Priority carryover requirements for 2023-24

  • No priority carryover requirements for 2023-24

1 Lakes Bulla, Hattah, Little Hattah, Lockie, Mournpall and Yerang.
2 Lakes Arawak, Boich, Bitterang, Brockie, Cantala, Konardin, Nip Nip, Roonki, Tullamook, Woterap and Yelwell.

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: 01/07/22