Rising as the Barcoo on the northern slopes of the Warrego Range, Queensland, the Cooper Creek flows north-west to Blackall. Joined by the Alice River, it continues south-west past Isisford and receives its
principal tributary, the Thompson. At Currareva, with the catchment area of 150 220 km2, the mean annual flow is 3.35 km3 with a standard deviation of 3.45 km3 for 33 full climatic years between 1939 and 1984.
Crossing the South Australian border near Innamincka, Cooper Creek cuts through a range of hills and these, in a similar
manner to the slight constriction of the Diamantina at Birdsville, offer the only chance of accurately measuring the flow anywhere within the 500 km of its central reach. The location also provides a
potential major dam site, a feature almost entirely missing on the other rivers of the Lake Eyre Basin.
The catchment area at Innamincka is 236 700 km2, and the mean annual flow for the period 1973-83 is 2.06 km3 with a standard deviation of 3.63 km3. The highest annual flow was 11.47 km3 in 1974; the highest monthly flow 6.49 km3 in February 1974; and the highest instantaneous flow 3 740 m 3/s on 18 February 1974.
Immediately downstream of Innamincka in periods of high flows, water is diverted through a natural control into the Strzelecki Creek, which also has a
catchment of its own and can flow due to the effect of heavy localised storms. Flow in Strzelecki Creek fills Lake Blanche, Lake Callabonna and Lake Frome in that order. In 1974, overflow from Lake Blanche also
reached Lake Gregory. It appears possible - and on some occasions probably inevitable - that Lake Gregory may overflow in a northwestern direction to Cooper Creek. If this is the case, then Strzelecki water can
re-enter Cooper Creek in the vicinity of Lake Killamperpunna. This did not happen, however, in 1974-76.
Once Cooper Creek leaves the hills of Innamincka, it emerges on to a very wide floodplain in the Sturt
Stony Desert, interlaced with channels, billabongs and lakes, and intersected by lines of north-south dunes. These floodplains of its central reach are highly complicated.