The Macquarie Marshes support many important species that are listed in international agreements and include vulnerable and endangered species. Appendix B provides a summary of the conservationally significant species recorded at the site. The ecological value of Macquarie Marshes is reflected in its rating against the criteria used by the MDBA to identify key environmental assets within the Basin. The MDBA established five criteria based on international agreements and broad alignment with the National Framework and Guidance for Describing the Ecological Character of Australian Ramsar Wetlands (Department of the Environment, Water, Heritage and the Arts 2008) and the draft criteria for identifying High Conservation Value Aquatic Ecosystems (SKM 2007). Based on the ecological values identified at the Macquarie Marshes, the site meets all of the five criteria for determining a key environmental asset (Table 1). Table 1 Assessment of the Macquarie Marshes against MDBA key environmental asset criteria Criterion Ecological values that support the criterion 1. The water-dependent ecosystem is formally recognised in international agreements or, with environmental watering, is capable of supporting species listed in those agreements The Macquarie Marshes are formally recognised in, or are capable of supporting species listed in the Japan–Australia, China–Australia or Republic of Korea – Australia migratory bird agreements. The Macquarie Marshes Nature Reserve, Mole Marsh and the Wilgara Wetlands met the five criteria for Ramsar listing. Species listed in international agreements that have been recorded at Macquarie Marshes are in Appendix B. 2. The water-dependent ecosystem is natural or near-natural, rare or unique The water-dependent ecosystem is natural or near-natural, rare or unique The Macquarie Marshes are one of the largest inland semi-permanent wetlands in Australia. The site is rare in terms of both its size and diversity of wetland types (Paijmans 1981; NSW National Parks and Wildlife Service1993; NSW Department of Environment, Climate Change and Water 2010c).
Flow delivery constraints Basin wide environmental objectives have been developed within the context of being deliverable in a working river system that contains public and private storages and developed floodplains. To understand and assess the implications of key constraints on the ability to achieve flow indicators at the Macquarie Marshes, MDBA has drawn upon a combination of existing information (e.g. Water Sharing Plans, flood warning levels) and practical knowledge of river operators supported by testing using modelling. The watering requirements (and thus objectives) of Section 5 are met through an appropriate water delivery regime. Implementation of a delivery regime is potentially subject to a number of constraints that may mean that environmental requirements are not met at all times. An example of the constraints that apply to water delivery to the Macquarie Marshes is given below: Prolonged flows of more than about 4,000 ML/d at Marebone Weir will cause flooding of Gradgery Lane. Under current operating practices high priority is given to minimising the period that a flow of 4,000 ML/d at Marebone Weir is exceeded. Recognising that the delivery of environmental flows is highly on existing system constraints, the site-specific flow indicators for the hydrologic indicator sites across the Basin have been classified into three broad types (Table 6). Despite the delivery of environmental flows being highly dependent on existing system constraints, the site-specific flow indicators for Macquarie Marshes are considered to be deliverable as mostly regulated flows under current operating conditions. Table 6 Site-specific flow indicators for the Macquarie Marshes and effect of system constraints Site-specific ecological targets Site-specific flow indicators Provide a flow regime which ensures the current extent of native vegetation of floodplain and wetland communities is sustained in a healthy, dynamic and resilient condition Provide a flow regime which supports the habitat requirements of waterbirds and is conducive to successful breeding of colonial nesting waterbirds Provide a flow regime which supports recruitment opportunities for a range of native aquatic species (e.g. fish, frogs, turtles and invertebrates) Provide a flow regime which supports key ecosystem functions, particularly those related to connectivity between the river and the floodplain Achieve a total in-flow volume of 100 GL during June to April for 80% of years Achieve a total in-flow volume of 250 GL during June to April for 40% of years Achieve a total in-flow volume of 400 GL during June to April for 30% of years Achieve a total in-flow volume of 700 GL during June to May for 17% of years