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 1 was the first to be completed at Blanchetown in 1922. Other weirs and locks were progressively constructed, with Yarrawonga Weir being the last to be completed in 1939.

The purpose of weirs and locks 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
  • allow river vessels to navigate through the weir via a 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, town and industrial consumption. 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. The location of the weirs is shown in a diagram of the River Murray System.

The River Murray system.

Under 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 and 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, work commenced to build fishways at all structures along the River Murray from the Murray Mouth up to, but not including, Hume Dam.

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

Name and location

River distance from Murray Mouth (km)

Elevation at full supply level (metres)

Typical head difference (metres)

Year completed

State responsible for operation and maintenance

Weir and lock 1

Blanchetown

274

3.3

2.5

1922

SA Water

Weir and lock 2

Waikerie

362

6.1

2.8

1928

SA Water

Weir and lock 3

Overland Corner

431

9.8

3.7

1925

SA Water

Weir and lock 4

Bookpurnong

516

13.2

3.4

1929

SA Water

Weir and lock 5

Renmark

562

16.3

3.1

1927

SA Water

Weir and lock 6

Murtho

620

19.2

2.9

1930

SA Water

Weir and lock 7

Rufus River

697

22.1

2.8

1934

SA Water

Weir and lock 8

Wangumma

726

24.6

2.5

1935

SA Water

Weir and lock 9

Kulnine

765

27.4

2.8

1926

SA Water

Weir and lock 10

Wentworth

825

30.8

3.4

1929

State Water NSW

Weir and lock 11

Mildura

878

34.4

3.7

1927

Goulburn–Murray Water Victoria

Weir and lock 15

Euston

1110

47.6

5.0

1937

State Water NSW

Weir and lock 26

Torrumbarry

1638

86.05

6.2

1924

Goulburn–Murray Water Victoria

Yarrawonga weir

1992

124.9

8.0

1939

Goulburn–Murray Water Victoria