These are a very extensive wetland system that covers 220,000 hectares of the region. They are one of the largest semi-permanent wetlands in south eastern Australia.
Starting at the Marebone Weir some 50 kilometres north of Warren, they extend northwards for 100 kilometres until the many and varied channels become one near Carinda. There are a number of major channels in the system including the Bulgeraga, Monkeygar, Buckiinguy and Terigal Creeks, the Bora Channel, Oxley and Marebone Breaks and the Gum and Long Plain Cowals. The reserve itself covers 18,150 hectares.
The fauna of the region includes several mammal species,. The Crucifix Toad and the Water-holding Frog are just two of 14 recorded species of frogs found in the region.
Nearly 200 species of birds are known to inhabit the marshlands with teh Weebill being the smallest and the Emu as the largest. Many reptile species also inhabit the area.
This region is a renowned breeding area and habitat for many waterbirds with 42 species known to reed in the area. These include 4 species of Egrets, 3 species of Ibis as well as Comorants, Spoonbills and Herons.