The Lachlan Catchment contains eight nationally significant wetlands, five associated with the swamps and effluent creeks in the lower catchment (Great Cumbung Swamp, Booligal Wetlands, Cuba Dam, Lake Merrimajeel—Murrumbidgil Swamp and Merrowie Creek–Cuba Dam to Chillichil Swamp) and three in the middle catchment (Lake Cowal–Wilbertroy Wetlands, Lake Brewster and Lachlan Swamp; (NOW, 2010c)).
The eight nationally significant wetlands have been recognised, through the Directory of Important Wetlands in Australia, as providing important waterbird habitat and also as good examples of a number of wetland types found associated with lowland rivers.
The criteria by which nationally significant wetlands have been selected include:
- It is a good example of a wetland type occurring within a biogeographic region in Australia;
- It is a wetland which plays an important ecological or hydrological role in the natural functioning of a major wetland system/complex;
- It is a wetland which is important as the habitat for animal taxa at a vulnerable stage in their life cycles, or provides a refuge when adverse conditions such as drought prevail;
- The wetland supports 1% or more of the national populations of any native plant or animal taxa;
- The wetland supports native plant or animal taxa or communities which are considered endangered or vulnerable at the national level; or
- The wetland is of outstanding historical or cultural significance.