right|thumb|Dead and dying River Red Gums on the lower Murray near Berri, South Australia 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.
right|thumb|Dead and dying River Red Gums on the lower Murray near Berri, South Australia 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.