By far the largest waterway in inland western Victoria, the Wimmera River rises not far from Ararat and runs west, gathering most of its flow from the Pyrenees and the northern Grampians, before turning north near Horsham and gradually dwindling into the semi-arid sands of the Mallee, eventually — in a good year — emptying into Lake Hindmarsh near Jeparit. From there it is known as Outlet Creek, which in wet years continues blindly north towards the Murray, filling the very large, shallow lake beds along its course one by one. It never reaches the Murray. The vast Wirrengen Plain near the northern edge of the Big Desert hasn't filled since the middle of the 19th century, and because of diversions for irrigation much further south, will never fill again.