The Wimmera River rises in the Pyrenees Range near Elmhurst and flows through Horsham, Dimboola and Jeparit before terminating at Lake Hindmarsh, which is Victoria's largest freshwater lake and the first of a series of terminal lakes. The Wimmera receives flows from several regulated tributaries including the MacKenzie River and the Mount William and Burnt creeks. These tributaries, Bungalally Creek and the Wimmera River downstream of Mount William Creek can receive environmental water. In exceptionally wet periods, Lake Hindmarsh may overflow into Outlet Creek and on to Lake Albacutya, an internationally recognised Ramsar-listed wetland. There are several wetlands beyond Lake Albacutya as well.
The waterways in the Wimmera system hold significance for Traditional Owners and their Nations. The Registered Aboriginal Parties (RAPs) in the Wimmera River catchment are the Barengi Gadjin Land Council Aboriginal Corporation (BGLC) and Martang Pty Ltd. Representatives of the BGLC were engaged during the preparation of this section. A trial watering is proposed for the Ranch Billabong near Dimboola, on land managed by BGLC. The intent is to provide a more-natural flooding regime in the billabong system to restore native plant and animal habitats that have been disconnected by levies and changed watering regimes in the Wimmera River. Ranch Billabong is also very significant to the Traditional Owners and their Nations, and it was the home of many generations of Wotjobaluk peoples.