Weirs and locks

After the establishment of the River Murray Commission in 1917, regulating structures including weirs and locks were constructed along the River Murray. Weir and Lock 1 at Blanchetown was the first to be completed in 1922. Other weirs and locks were progressively constructed, with Yarrawonga Weir being the last to be completed in 1939 and the only weir which does not have a lock.

The purpose of the weirs is to:

• store water for consumptive use and to regulate river flow downstream
• provide a raised river level upstream of the weir to improve the navigability of the river (vessels can navigate through the weir via its lock).

The weirs and their weir pools – the water stored behind the weir – provide bodies of water at higher levels than would otherwise be present. This allows water to be diverted for agricultural, domestic and industrial use. The weir pools and locks also enable recreational activities.

There are 14 weirs along the River Murray – all except Yarrawonga Weir include a navigation lock. The weirs at Mildura, Torrumbarry and Yarrawonga were constructed primarily for water supply, rather than navigation. 

During regulated (non-flood) conditions, boats can move from upstream to downstream (or vice versa) using a navigation lock to by-pass the weir.

Downstream from Euston Weir (Lock 15) to Lock 1, it is necessary to partially remove sections of the weir to prevent damage during floods, and to facilitate navigation without the use of the lock.

There are 4 types of weir construction on the Murray:

• concrete piers, combined with removable sections including stop-logs (Weirs 1 to 10 and Weir 15 at Euston)
• steel trestles running on rails across the bed of the river (Mildura Weir; and originally at Torrumbarry Weir before it was replaced by a concrete and gated weir)
• concrete piers with large radial gates (Torrumbarry Weir)
• earth bank and concrete weir with large vertical lift gates (Yarrawonga Weir).

Fishways

Fishways enable fish to pass through a river structure such as a weir. The first fishways constructed on the River Murray were at Weir 6 and Euston Weir. A fish lift was installed at Yarrawonga Weir in 1995 and the original fishway at Torrumbarry Weir was replaced in 1996. More recently, fishways have been retrofitted at the other structures along the River Murray from the Murray Mouth up to, but not including, Hume Dam; thereby allowing fish passage from ‘Hume to the Sea’.

Hydro-electricity

At Yarrawonga Weir, a hydro-electric power station generates electricity. This can occur due to relatively high (regulated) flow rates and adequate head difference – the height between the water level behind the weir and the river immediately downstream of the power station. While we do not own the power station, generation of power must be undertaken within the requirements for regulated flow release from the weir.

Weir and lock information