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Hattah-Kulkyne National Park is situated in north-western Victoria adjacent to the River Murray (Figure 5.2.4) The national park contains a complex of more than 20 semipermanent freshwater lakes known collectively as Hattah Lakes. The ecology of the lakes and floodplain is strongly influenced by flooding regimes of the River Murray. The construction of a permanent pump station, regulators and levees at Hattah Lakes in 2013 has enabled greater volumes of water for the environment to be delivered to the site, to return a more-natural, healthy pattern of flooding to the lakes.

Hattah Lakes is an important place for Traditional Owners and their Nations. Currently there is no Registered Aboriginal Party for the region and the Mallee CMA involves the region's Traditional Owners in the management of Hattah Lakes through its Aboriginal Reference Group, which includes First Peoples of the Millewa-Mallee and the Wadi Wadi and Tati Tati Traditional Owners.

System map

Environmental watering objectives in the Hattah Lakes

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Provide feeding and breeding habitat for a range of waterbird species including threatened and migratory species and colonial nesting species (such as the spoonbill and egret)
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Rehabilitate a healthy and diverse mix of wetland and floodplain plant life to maintain the ecological character of this internationally protected site

Environmental values

Hattah Lakes is home to a diverse range of flooddependent 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 every four to five years. Regulation of the River Murray has resulted in less-frequent floods of shorter duration, and many of the vegetation communities across the site do not receive enough water without the delivery of environmental water. A combination of natural flooding and delivery of water for the environment since 2010 has improved canopy health and recruitment of black box communities.

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 habitat for native fish and terrestrial animals. The endangered freshwater catfish is known to inhabit the lakes.

Social and economic values

Hattah-Kulkyne National Park is a popular location for camping, canoeing, birdwatching and photography. Local businesses in the area benefit from increased visitation following environmental watering and natural flooding events.

Conditions 2018

Environmental watering in 2017–18 aimed to improve the health of black box woodland on the Hattah Lakes floodplain and to consolidate some of the ecological outcomes that were triggered by natural floods in spring 2016.

Looking back two years to July 2016, it was not anticipated that any water for the environment would be provided to Hattah Lakes. The seasonal outlook was dry and some of the lower-lying lakes had received water three times in the previous four years, so wetland drying was considered appropriate to draw down lake levels to allow seeds to germinate and plants to establish themselves on the edges of the wetland.

Winter and spring 2016 were wetter than expected, so a decision was made to deliver water for the environment to Hattah Lakes during September and October 2016 to align with the wet conditions. Late October and November 2016 brought the largest floods in the River Murray in the last two decades. The Hattah Lakes and floodplain were inundated for 16 consecutive weeks and reached a maximum level of 44.6 m AHD (Australian Height Datum), providing perfect conditions for the recovery of black box trees that had not been flooded since the 1990s.

The ecological productivity boost and increase in new plant growth associated with floods can be short-lived without significant watering in the subsequent year. Over 110 GL of water for the environment was delivered to the Hattah Lakes between July and October 2017 to support the further germination, growth and recovery of black box trees. The water delivery aimed to inundate as much of the Hattah Lakes as possible within the constraints of the available infrastructure. Water levels throughout the lakes reached 44.85 m AHD, which is the highest inundation by environmental or flood water since the 1970s. Recent monitoring indicates that black box health has improved, with tree canopy cover increasing in areas that received water for the environment in 2017–18.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Hattah Lakes

Potential environmental watering1

Environmental objectives

Wetland watering

Natural inundation of Chalka Creek and Hattah Lakes

  • Allow natural connectivity between Hattah Lakes and the River Murray 
  • Allow exchange of carbon, nutrients and biota between the wetlands and the River Murray

Wetland drying

Drying of Hattah Lakes
  • Maintain the lake bed herbland as water levels recede 
  • Allow drying of lakes to manage carp and improve wetland condition

1 The Hattah Lakes pump station will also be operated to meet annual maintenance requirements.

Risk management

In preparing its seasonal watering proposal, North Central 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

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
  • Birdlife Australia (Mildura) 
  • Commonwealth Environmental Water Office 
  • Department of Environment, Land, Water and Planning 
  • Goulburn-Murray Water 
  • Landcare Groups (Kulkyne Way Landcare, Red Cliffs and District Landcare, Annuello [Robinvale and District] Landcare, Robinvale lndigenous Landcare, Sea Lake Landcare and Manangatang Landcare) 
  • Mallee CMA Aboriginal Reference Group including First Peoples of the Millewa-Mallee and members of the Wadi Wadi and Tati Tati Traditional Owners groups 
  • Mallee CMA Water Technical Advisory Committee (an advisory group to Mallee CMA comprising community members) 
  • Mid-Murray Field Naturalists 
  • Mildura Rural City Council 
  • Mildura 4WD lnc. 
  • Murray–Darling Basin Authority 
  • Parks Victoria 
  • Sunraysia bushwalkers 
  • Sustainable Living Mildura 
  • Victorian Environmental Water Holder 
  • Wildside Outdoors