The construction and operation of Lake Eppalock has significantly altered downstream river flows and reversed seasonal flows. Lake Eppalock captures rainfall run-off and reduces natural winter and spring flows downstream. The stored water is then released at a higher-than-natural rate over summer and autumn to meet downstream irrigation demand in the reaches between Lake Eppalock and the Campaspe Siphon. Environmental water is held and released from Lake Eppalock, with some limited ability to regulate flows further downstream at the Campaspe Weir.
Higher-than-natural flows throughout summer may reduce the amount of suitable habitat for juvenile fish, which rely on protected shallow areas of water near the edge of the river channel. Delivering water to users downstream in the River Murray when they need it over summer is essential, and storage managers and the CMA have been working together to limit any negative effects these transfers may have on native plants and animals.
Providing the target flows in all reaches below Lake Eppalock is important. Environmental water is usually released from Lake Eppalock to meet specific flow targets in reach 4 (that is, downstream of Rochester). These flows also achieve the desired flow objectives in reaches 2 and 3 between Lake Eppalock and Rochester. Primary flow measurement points are at Barnadown (reach 2) and downstream of the Campaspe siphon (reach 4). In specific circumstances, water can be delivered to reach 4 from the Goulburn system via the Waranga western main channel.