The river as a highway: Locking the river

Regulating the flow of the River Murray, and its tributaries (particularly the Darling and Murrumbidgee) was meant to even out seasonal variations in the river level. Steamboat navigation on the Murray River system was the first commercial use of the river, and in a good year the river was navigable for about eight months, and for a distance of some 5000 kilometres.

Low water at the end of summer produced some difficulties, with exposed sand bars, rocks etc. And then there were the drought years, when the rivers ran dry. When the irrigators arrived on the Murray in the 1870s, they wanted a more even, controlled flow of water, and in particular needed it in the peak or summer season. Irrigators and navigators were set for conflict.

The droughts of the late 19th century which culminated in the major drought of 1902, resulted in agreement being reached that 'drought proofing' the river was essential. It would be another decade before the Federal and three State governments would reach accord on the control of the rivers.

The River Murray Waters Agreement was signed by all in 1915.  The main points of the Agreement, as they effect South Australia, remain very much the same today:

• New South Wales and Victoria retain control of tributaries.
• South Australia receives a guaranteed minimum quantity of water, its "entitlement."
• Storages on the upper Murray (the Hume Reservoir was the site selected) and at Lake Victoria.
• A series of 26 locks and weirs reaching as far as Echuca, and a further 9 on the Murrumbidgee.

The storages at the Hume Reservoir (NSW) and Lake Victoria (NSW) would increase water supply security, and would be released as necessary to supplement low flows.  The locks and weirs would ensure the rivers were navigable at all times and provide for irrigation.

The locks would also be sited to best assist irrigation using gravity. By 1924 when the agreement was amended to prioritise building of irrigation structures rather than those required for navigation, riverboat trade was already declining due to the increase in railways. In 1934 the difficult economic conditions of the Great Depression caused the agreement to be further amended-14 locks and weirs would be built instead of the original 26, and as well, barrages would be constructed at the Murray Mouth. These last would prevent sea water flowing into Lakes Alexandrina and Albert and upriver and assist fresh water irrigation in the district.

The locks in South Australia are:

• Blanchetown: Lock 1
• Waikerie: Lock 2
• Kingston: Lock 3
• Berri: Lock 4
• Renmark: Lock 5
• Paringa: Lock 6

Between the NSW border and the River Darling: Locks 7-10

Further reading

River Murray Commission (Australia). R.M.C.:Harnessing Australia's greatest river: the work of the River Murray Commission / compiled by A.F. Ronalds. Melbourne: the Commission, 1950

Harnessing Australia's greatest river: details of the great scheme undertaken by the governments of the Commonwealth of Australia, and of the States of New South Wales, Victoria and South Australia, Melbourne : The Industrial Australian and Mining Standard, 1920

Linn, Rob. Murray water is thicker than blood: the stories of the families who made the River Murray's locks and barrages, Waikerie, S. Aust: Historical Consultants for River Murray Locks & Barrages Reunion Committee, 2001

Links

Murray-Darling Basin Authority 

MurrayCare: River Murray Urban Users Committee See: Resources: RMUUC Fact Sheets River regulation and diversion

Save the Murray See: History: River regulation