In the 19th century the river used to support a substantial commercial steamboat trade, but the unreliable levels made it impossible for boats to compete with the railways and later road transport. However, the river still carries pleasure boats along its entire length. During the 20th century a large number of dams were constructed in the river's headwaters, including the Hume Dam, Dartmouth Dam, and the complex dam and pipeline system of the Snowy Mountains Scheme. These dams inverted the patterns of the river's natural flow from the original winter-spring flood and summer-autumn dry to the present low level through winter and higher during summer. These changes ensured the availability of water for irrigation and made the Murray Valley Australia's most productive agricultural region, but have seriously disrupted the life cycles of many ecosystems both inside and outside the river, and the irrigation has led to dryland salinity that now threatens the agricultural industries.
The disruption of the river's natural flow, runoff from agriculture, and the introduction of pest species like the European Carp has led to serious environmental damage along the river's length and to concerns that the river (and thus Adelaide's water and the irrigation water) will be unusably salty in the medium to long term. Efforts to alleviate the problems proceed but political infighting between various interest groups stalls progress.