The riverine wetlands and associated floodplains of the Victorian Mallee provide habitat for a range of terrestrial and aquatic plants and animals. These areas are important breeding and nursery grounds and provide refuges in times of drought.
Hattah Lakes (Lake Hattah, Lake Little Hattah, Lake Bulla and Lake Arawak) after emergency red gum watering, spring 2009.
While these wetlands and floodplains have endured and survived centuries of weather extremes (such as drought and floods) their environmental patterns have altered significantly since European settlement. For example, the Murray River system and many of its tributaries and wetlands have been regulated for irrigation, industrial and domestic water supply, and during early settlement for river navigation. This has had a major impact on natural flooding patterns.
River regulation has significantly decreased the frequency, magnitude and duration of flooding events and has affected the timing and seasonality of flows. In other words, while the flooding of some wetlands still occurs it may be at the wrong time of year or doesn’t last long enough to provide the maximum benefits to the plants and animals that depend on it.
Regulation of our waterways has been extremely beneficial to the communities and industries that are reliant on the improved water security that regulation provides. But over time these changed river flows (exacerbated recently by prolonged and widespread drought) have taken their toll on riverine and floodplain environments. The result has been a reduction in the diversity of plant and animal life and a decline in the health of the region’s majestic Red Gum and Black Box woodlands. In some areas along the lower reaches of the Murray River, up to 100 percent of Red Gums are highly stressed or near death as a result of inadequate flooding over the past decade.
Other side-effects of changed water regimes include the increased salinisation in floodplain areas, algal blooms and the increased occurrence of pest plants and animals.
Both the state and federal governments have recognised the need to intervene to provide environmental water allocations to those areas most affected, through programs such as the Murray Darling Basin Authority’s The Living Murray (TLM) program, as well as the Victorian Government’s Murray River Flora and Fauna bulk entitlement for the environment, the Victorian Government’s Our Water Our Future initiative, the creation of an Environmental Water Reserve and, more recently, the Commonwealth Government’s environmental water entitlements.
Under the The Living Murray program, 500 gigalitres will be returned to the Murray River to increase flows to wetlands and floodplain environments at six key ‘icon sites’. Two of the icon sites are located in the Victorian Mallee - the Hattah Lakes Icon Site; and Lindsay, Wallpolla and Mulcra Islands component of the Chowilla (including Lindsay Wallpolla) Icon Site.
The Mallee Catchment Management Authority (CMA) is working with the community, the Murray Darling Basin Authority, Department of Sustainability and Environment (DSE), Parks Victoria, regional water authorities and other regional partners to identify and implement improved water management at these icon sites and other priority areas in the Victorian Mallee.
This has involved the development of comprehensive environmental management plans for the TLM icon sites, the development of numerous water management investigations aimed at improved environmental flows at key wetlands and floodplain areas across the Mallee region, and the implementation of on-ground activities (such as the construction of regulators and the delivery of environmental water to priority wetlands and floodplain areas).
These on-ground activities have included:
the construction of wetland regulator structures at Webster’s Lagoon on Lindsay Island and Horseshoe Lagoon on Wallpolla Island to better mimic natural flooding regimes by allowing the wetlands to fill during late winter and spring and dry through summer and autumn;
the construction of new regulators and the raising of the Old Mail Route at Lake Wallawalla to allow high flows that flood the wetland to be retained;
the delivery of a comprehensive Mallee environmental watering program along the lower reaches of the Murray River, which to December 2006 has involved the provision of 61.6 gigalitres (billion litres) of environmental water to priority sites along the Murray River, including a total of 6.9 gigalitres of water donated from irrigators in the Mallee.
Regulator at Hattah Lakes during Environmental Watering event in late 2009.
Further information about the icon site environmental watering plans can be found on the Murray Darling Basin Authority website.
The Department of Sustainability & Environment have developed a Flickr page containing information and pictures on environmental watering and other projects of interest. For the more mobile of us they are also available on Twitter.
The links to both web sites are: