The nature reserve extends over an area of almost 20,000 hectares (49,000 acres), approximately 10% of the Macquarie Marshes floodplain.

The North and South Marsh Nature Reserves were listed as a wetland of international importance in 1986 under the Ramsar Convention of 1971.

[6] The wetlands contain a wide range of vegetation types, primarily determined by the frequency and duration of flooding.

The dominant types are river red gum forest and woodland, as well as extensive beds of common reed.

A number of birds are listed as vulnerable or threatened including the magpie goose, blue-billed duck, freckled duck, Australasian bittern, brolga, painted snipe, osprey, glossy black cockatoo, turquoise parrot, square-tailed kite and Major Mitchell's cockatoo.