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 5.2 Victorian Murray system
5.2.4 Hattah Lakes
System overview
The Hattah-Kulkyne National Park is situated
in north-west Victoria adjacent to the Murray River (Figure 5.2.4). The national park contains
a complex of more than 20 semi-permanent freshwater lakes known collectively as the Hattah Lakes.
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 has also been constructed that can deliver up to 1,000 ML per day to 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.
Lake Kramen in the south east of Hattah-Kulkyne National Park is disconnected from the main Hattah Lakes complex. The Hattah Lakes pump station can deliver up to 145 ML per day to Lake Kramen to restore flooding regimes.
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 benefited 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 waterbirds and terrestrial animals.
The Hattah Lakes support native fish species such golden perch and endangered freshwater catfish, which can move between the lakes and the Murray River when flows are suitable. Fish can also persist in permanent wetlands in the Hattah Lakes during dry years.
Environmental watering objectives in the Hattah Lakes
     Increase the native fish populations
    Restore and maintain a mosaic of healthy wetland and floodplain plant communities
   Provide feeding and nesting habitat for the successful recruitment of waterbirds and woodland birds
   220 | Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21

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