 The upper reaches of the Ord River are permanently fresh; the lower reaches, when not in flood, become saline due to the tidal cycle which, at the coast, has an amplitude of up to 8 m. Within the site the upstream end of the river channel is around 150 m wide with broad sand and gravel spits, while unstable mud bars and islands characterise the 5 km wide mouth.From the mouth of the Ord River, the site extends northwards around the coast to include the False Mouths of the Ord, consisting of a maze of deltaic channels, intertidal mudflats and low muddy islands, an area which receives only a little fresh water from small and ephemeral creeks.The site has a dry tropical climate.