The Loddon River flows north from its headwaters near Daylesford towards the River Murray. Tullaroop Creek is the main tributary in the upper Loddon River system. The middle section of the Loddon River includes Serpentine Creek and is characterised by many distributary streams and anabranches flowing north across a broad floodplain. The lower Loddon River is joined by Pyramid Creek at Kerang and at this point the Loddon becomes part of the River Murray floodplain.
The major storages in the Loddon River system are Cairn Curran, Tullaroop and Laanecoorie reservoirs. Downstream of Laanecoorie Reservoir the river is further divided into sections due to the Bridgewater, Serpentine, Loddon and Kerang weirs.
Environmental water can be delivered to the Loddon River from Cairn Curran or Tullaroop reservoirs or from the Goulburn system via the Waranga Western Channel (which intersects the Loddon River at Loddon Weir). Water is provided to Pyramid Creek from the Murray system via the National Channel. Water is diverted from the Loddon River to Serpentine Creek and to the Boort Irrigation District to supply agriculture.
The water distribution system in the Loddon is very complicated due to modifications to the natural waterways for irrigation supply. The modifications to waterways and irrigation infrastructure provide challenges and opportunities for effective environmental water management. The highly regulated system makes it possible to manipulate the timing of releases at multiple locations, providing opportunities to accomplish environmental outcomes at discrete locations. However there are also many barriers that limit continuity and constraints that affect the volume and timing of environmental water releases.
The highest-priority reach for environmental watering is from Loddon Weir to Kerang Weir, because there is good potential to rehabilitate environmental values and because the reach doesn't carry irrigation water. Environmental water releases to this reach aim to improve the condition of riparian vegetation and increase the abundance of native fish. Environmental water is also delivered to the upper Loddon River, Tullaroop Creek and Serpentine Creek to maintain or increase populations of river blackfish and platypus.