The Darling River is simply not supposed to dry out, even in drought
The Barwon-Darling River is a “dryland river”, which means it is naturally prone to periods of extensive low flow punctuated by periods of flooding.
However, the presence of certain iconic river animals within its channels tell us that a dry river bed is not normal for this system. The murray cod, dead versions of which have recently bought graziers to tears and politicians to retch, are the sentinels of permanent deep waterholes and river channels – you just don’t find them in rivers that dry out regularly.
Less conspicuous is the large river mussel, Alathyria jacksoni, an inhabitant of this system for thousands of years. Its shells are abundant in aboriginal middens along the banks. These invertebrates are unable to tolerate low flows and low oxygen, and while dead fish will float (for a while), shoals of river mussels are probably dead on the river bed.
via The Conversation The Darling River is simply not supposed to dry out, even in drought