The Lake Eyre Basin is one of the biggest internal drainage systems in the world, extending across the south east of the Northern Territory, south west Queensland and north east South Australia. The basin is equal in size to the area of South Australia and overlies the Great Artesian Basin. The floodwaters that flow into the lake are from the higher rainfall districts of south west Queensland.
Each time the lake floods, the salt crust which forms much of the surface of the lake begins to dissolve until the salt level in the water reaches saturation point. When the lake starts to fill, the surface water is fairly fresh and drinkable because the heavier salty water is close to the lake bottom. From the air, water salinity variations can be seen as remarkable swirling current patterns.
Vegetation is generally sparse in the park. Canegrass and scattered clumps of mulga and acacias grow on the red sand dunes and the occasional stand of acacia can be seen on the coarse gibber tablelands. Nitre-bush, samphire, needlebush and native willow are also found in the Lake Eyre area. After heavy local rain the landscape bursts into colour and is surrounded by a sea of grass-green foliage. The flowers produce an abundance of nectar and seeds that attract many insects and in turn, flocks of birds.
Generations of desert animals have had to adapt in order to survive in the harsh environment of Lake Eyre such as the Lake Eyre dragon. This lizard lives out on the dry lakebed eating ants and sheltering under the salt crust on the deep mud layer.
If you are lucky enough to visit during a flood you may witness the lake hosting a chaotic community of breeding birds that have flown thousands of kilometres from as far away as China and Japan.
Under the waterline, bony bream and hardyhead, shrimp and perch all begin their own breeding and feeding frenzies as water fills the lake. The Lake Eyre hardyhead can survive in water up to 15 times saltier than seawater so it can continue feeding and breeding as the other fish around it succumb to the salty water as the fresh water evaporates.