Twelve years after the Royal Commission on the River Murray, the Commonwealth, New South Wales, Victoria and South Australia governments signed the River Murray Waters Agreement in 1914. The main items of the Agreement were provisions to construct several storage areas, to build 26 weirs and locks on the Murray between Blanchetown (South Australia) and Echuca (Victoria), and to build nine weirs and locks on the lower part of either the Murrumbidgee or the Darling. The agreement was later ratified by the Commonwealth and State governments and came into operation in 1915. In 1917 the River Murray Commission was established to administer the Agreement. The Commission would manage the efficient sharing the Murray's waters between the three states and coordinate the construction of the locks and weirs by the state building authorities. The River Murray Commission was comprised of delegates from each state and a Commonwealth appointed chairman.
During this period, the River Murray Commission coordinated the construction of storage facilities and locks and weirs. Major works included the Hume Dam begun in 1919, Blanchetown lock/weir and Lake Victoria storage. In 1934, during the Great Depression, major amendments were made to the River Murray Waters Agreement to rationalise works on the river. The rise of the railways and demise of river trade had caused a change in the major use of the river-the emphasis was now on irrigation rather than navigation, so only locks and weirs that aided irrigation diversion were constructed.
In 1940 the construction of five barrages across the Murray Mouth was completed. These prevent salt water from the ocean from entering Lake Alexandrina and the Lower Murray and help maintain a stable water level in these areas.
After the alarming findings of investigations by the River Murray Commission into salinity levels in the River in the late 1960s, the River Murray Waters Agreement was eventually amended again significantly in 1982 to expand its scope to include water quality issues and environmental and recreational matters.