The construction and operation of Lake Eppalock has significantly altered downstream river flows and reversed the seasonal flows. The storage captures rainfall run-off and reduces natural winter and spring flows downstream, which is then released as increased flows over summer and autumn. Environmental water is held and released from Lake Eppalock, with some limited ability to regulate flows further downstream at the Campaspe Weir.
Higher flows in summer can mean less suitable habitat for juvenile fish. Delivering water to users downstream in the River Murray when they need it over summer is essential, and storage managers and the North Central Catchment Management Authority have been working cooperatively to do this in an environmentally sensitive manner. This cooperation results in deliveries to downstream users having as little negative effect on native plants and animals as possible.
Providing the target flows in all reaches below Lake Eppalock is important. Environmental watering usually targets reach 4 which will also achieve the desired flow objectives in reaches 2 and 3 (see below). Primary 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.