None of the creeks and rivers in the Lake Eyre Basin are permanent: they flow only after heavy rain – a rare to very rare event in the arid interior of Australia. Average annual rainfall in the area surrounding Lake Eyre is , and the pan evaporation rate is . Annualised average figures are misleading: since 1885 annual rainfall over the of the Lake Eyre Basin has ranged from about in 1928 to over in 1974. Most of the water reaching Lake Eyre comes from the river systems of semi-arid inland Queensland, roughly to the north.