The Glenelg River rises in the Grampians and flows west through Harrow and then south to Casterton and Dartmoor for over 500 km, making it one of the longest rivers in Victoria. A short stretch of the estuary winds through SA before returning to Victoria to enter the sea at Nelson.
The Glenelg River is an integral part of the Wimmera-Mallee headworks system, which supplies towns and properties across the Western Region. Moora Moora Reservoir and Rocklands Reservoir in the upper Glenelg catchment and three weirs on the upper Wannon River are all used to divert water from the Glenelg system to the Wimmera catchment. Environmental water is actively managed in the main stem of the Glenelg River below Rocklands Reservoir, and passing flow rules are in place for the Glenelg River and upper Wannon River.
The priority environmental flow reaches of the Glenelg River are Rocklands Reservoir to 5-Mile Outlet (reach 1a), 5-Mile Outlet to the confluence with the Chetwynd River (reach 1b) and Chetwynd River to the Wannon River (reach 2). Environmental water in the Glenelg system is released from Rocklands Reservoir for reach 1a via the reservoir wall outlet and for reach 1b via the 5-Mile and 12-Mile outlets. Releases are made at these points to meet objectives in these reaches as well as in reach 2. The Glenelg River reach 3 and estuary benefit from environmental water releases to upstream reaches, but releases are not specifically targeted at these reaches.
The Glenelg River above Rocklands Reservoir (reach 0) runs mostly through the Grampians National Park and retains significant environmental values. Flows through this reach are affected by the operation of Moora Moora Reservoir and work is being undertaken to confirm its flow requirements. Work is also being undertaken to better understand the role environmental releases from Rocklands Reservoir play in the health of the Glenelg River estuary, which is listed as a heritage river reach and has been nominated for international listing under the Ramsar Convention.