Hume Dam
The construction of Hume Dam has caused significant changes to the flow patterns and ecology of the Murray River. Before the construction of the Hume Weir, flows in normal (non-drought) years were low in summer and autumn (though still significant overall), rising in winter due to seasonal rainfall and reaching a flood-peak in late spring due to snow-melt in the Murray and its tributaries' alpine headwaters. The flow is now effectively reversed, with low flows in winter and sustained, relatively high flows in late spring, summer and early autumn to meet irrigation demands, although the spring flood peak has been virtually eliminated. The water released from the base of the Hume Weir is unnaturally cold, at least 10 °C (18 °F) colder than it naturally should be. This flow reversal, temperature depression, and removal of the spring flood peak, has led to the drying out and loss of many billabongs and has harmed the populations of native fish of the Murray River such as the iconic Murray Cod and the freshwater catfish, which can no longer be found downstream of the dam as far as Yarrawonga, where it had previously been recorded up until the 1960s.