The Ovens system rises in the Great Dividing Range near Mount Hotham and flows about 150 km to join the River Murray in the backwaters of Lake Mulwala. Two small water storages have been constructed in the system: Lake Buffalo on the Buffalo River and Lake William Hovell on the King River. The regulated reaches of the Ovens system include the Buffalo River below Lake Buffalo, the King River below Lake William Hovell and the Ovens River from its confluence with the Buffalo River to the River Murray (as shown in Figure 1 below).
The Ovens system maintains quite good natural flows (particularly in winter-spring), compared to other regulated rivers. This is a result of relatively small storages that spill regularly and allow unregulated flows to the rivers.
The Ovens system contributes significantly to the water resources of the River Murray. The water that flows out of the Ovens River is regulated by the largest weir pool (Lake Mulwala) on the Murray regulated system. Ovens River flows contribute to the reliability and the variability of the flow regime for the River Murray and support many downstream uses including irrigation, urban supply and watering of iconic sites (such as Barmah Forest).
Environmental water is held in Lake Buffalo and in Lake William Hovell and can be released under regulated conditions when the storages are not spilling. Five reaches in the Ovens system can benefit from environmental water releases. While all are important, there are relatively small environmental holdings available in the system to meet the needs of all reaches. When water is only available from the holdings, outcomes in the reaches immediately downstream of the storages are targeted. When paired with consumptive water on its way to the Murray system, additional benefits are likely to be achieved downstream in the lower Ovens River.
Figure 1 The Ovens system