Document ID: chunk:federal_register_of_legislation:F2023L00138:front:0:p11
Version: federal_register_of_legislation:F2023L00138
Segment Type: other
Provision Reference: 
Character Range: 28208–31235

and Thomas 1995; Garnett and Crowley 2000; Kingsford 2000; Jaensch 2004; Garnett et al. 2011; DBCA 2018). Over the past 100 years, many suitable wetland sites in both eastern and south western Australia have been lost because of the alteration of habitat (Kingsford 2000; Garnett et al. 2011). Across the range of the species, proposals to expand or create new irrigation schemes (dams) need to be mindful of the potential impacts to Australasian Bittern and its habitats, particularly during extended drought conditions.

   In the Murray–Darling Basin, reduction in floodplain inundation due to water harvesting and alteration of drainage systems has adversely affected much of the Australasian Bittern's seasonal habitat (Jaensch 2004). Many of the Murray–Darling Basins wetlands are no longer inundated or are rarely available for use by the species due to river regulation and water harvesting for irrigation (Jaensch, pers. comm., 2005). For example, there has been a 70 per cent reduction in large water flows to the Gwydir Wetlands, New South Wales, which are listed as both nationally important and Ramsar wetlands. As a consequence, the Gwydir Wetlands now only floods five per cent of the time compared to a previous 17 per cent of the time (Kingsford 2000). In addition, the Macquarie Marshes Ramsar wetland has reduced in size by 40–50 per cent as a result of a 21 per cent decline in the flow of water to the wetland (Kingsford 2000).

   Flow regulation is impacting many rivers in the Murray–Darling Basin, with approximately 4,000 dams, weirs and other barriers (Lintermans 2007) facilitating water collection in impoundments, diversion through irrigation channels and direct pumping from rivers, largely for agricultural use. Across the Basin water regulation hassignificantly altered natural flow regimes, particularly regarding seasonal and inter-annual flows and floodplain inundation (Kingsford et al. 2015). It has also altered both the quality and availability of floodplain habitats, such as backwaters and billabongs, due to reduced flooding. The Murray–Darling Basin Authority has focused environmental water priorities on floodplain inundation to provide lateral connectivity (MDBA 2015). Environmental watering events in the Barmah-Millewa Ramsar site and Lowbidgee wetlands have supported significant numbers of Australasian Bitterns, with confirmed breeding (Belcher et al. 2016, Herring et al. 2019b). Watering events in the Kerang Lakes region, Lachlan, Macquarie and Gwydir catchments have most likely achieved similar breeding events that benefit the species in the Murray–Darling Basin.

   Increased extraction of groundwater due to escalating demand for water in urban areas and declining rainfall is another factor in wetland availability, especially on the Swan Coastal Plain, Western Australia (DBCA 2018). Groundwater dependent wetlands in this sandplain can be dry for longer periods. In contrast, as both an immediate and continued gradual consequence of clearing of woodland for