The Yarrawonga Weir is an earth-filled embankment dam across the Murray and Ovens rivers, located between and in the Hume region of Victoria and in the Riverina region of New South Walesin eastern Australia. The weir, situated in Victoria, was completed in 1939 to form the reservoir, Lake Mulwala, for the purposes of water supply for irrigation in the surrounding district, regulate river flow, and serve as a crossing of the Murray between Victoria and New South Wales. A hydroelectric power station and a fish lift were added in 1994.
Owned by the Murray–Darling Basin Authority, the dam and reservoir are operated by Goulburn–Murray Water. Transport for New South Wales manages the waterway and the NSW Department of Primary Industries manages fishing on the reservoir. the earth-filled dam wall is high and long. When full, at above sea level, the resultant reservoir has a storage capacity of and covers , drawn from a catchment area of .
The controlled ogee crest spillway has a discharge capacity of .
During time of high flows and floods, water takes approximately six days to reach the weir from the Murray's headwaters, some to the east. The Yarrawonga Weir is the farthest downstream dam or weir across the Murray that does not have a navigation lock through it. The weir is upriver from the river mouth, and is the largest of the fourteen weir across the Murray.
Reservoir
Below the weir, two gravity-fed channels supply water for irrigation. Developed as part of the Murray-Darling Irrigation Scheme, this irrigation project enhanced the productivity and prosperity of the district and provided opportunities for war veterans as part of a World War II–soldier settlement scheme. The Mulwala Canal, in New South Wales, has a discharge capacity of per day. The Yarrawonga Main Channel, in Victoria, has a discharge capacity of per day. Collectively, the channels release approximately per annum to serve an irrigated area of approximately . Despite having capacity of , in order to maintain full supply levels, of the reservoir is inactive.
Hydroelectric power station
The Yarrawonga Weir Power Station is a run-of-the-river hydroelectric power station that was commissioned in 1994. With a generating capacity of , the station has two Kaplan turbines, each with a capacity to generate . Operated by AGL Energy, the station is connected to the Victorian electricity grid via a 22 kV transmission line, and has an average annual output of .
Bridges
The Mulwala Bridge, a road bridge across Lake Mulwala, was built between 1917 and 1924, before the weir was completed and the reservoir filled. The road replaced an earlier wooden bridge built between 1889 and 1891. The 1924 road bridge bridge was started from both ends, each by the respective state government. However, they did not coordinate their efforts, and the bridge has a dip and a bend in the middle to make the two ends meet.
The reservoir is also crossed by a railway bridge.
Gallery
<gallery>
Lake Mulwala Stevage.jpg|The eastern end of the reservoir
LakeMulwala.JPG|View from Yarrawonga to Mulwala
Lake Mulwala Parks.JPG|Lake Mulwala seen from Mulwala
MulwalaCanalStart.JPG|Mulwala Canal, near the weir
Sunrise over Lake Mulwala-2and (4235480574).jpg|Sunrise over the lake
Sunset over Lake Mulwala-02and (4236785744).jpg|Sunset over the lake
LakeMulwalaEmpty.JPG|The river and lake in 2009
</gallery>
See also
- List of power stations in Victoria
- List of reservoirs and dams in New South Wales
- List of reservoirs and dams in Victoria
- List of run-of-the-river hydroelectric power stations
- Irrigation in Australia