What are the issues affecting the Murray Darling Basin?

Answer 1

The Murray River, together with its major tributary the Darling River, are two significant rivers in the southeastern quadrant of Australia. Along with their numerous tributaries, they form the Murray-Darling river system. This system feeds the Murray-Darling Basin, which covers 1 061 469 square kilometres, or about 14% of the Australian continent.

As a result, a very large part of Australia's most productive land relies on the Murray and Darling Rivers. The basin provides about 41% of the country's agriculture with water for crops such as cotton, rice and wheat. The problem is that rice and cotton require enormous amounts of water, and by redirecting the water for irrigiation, not only are cities and towns further downstream affected, but there is not enough freshwater flowing downstream to stop the increasing salinity problems of both rivers, particularly the Murray as it nears the coast.

Currently, the major problem facing the two main rivers and numerous tributaries of the Murray Darling basin is this rising salinity. This affects the vegetation and wildlife which are dependent on the Murray River. The water quality is severely depleted by the rising salinity, and this also results in land degradation. This is largely due to the extensive irrigation that has been carried out using the waters of the basin for many, many decades.

The introduction of the European carp has caused major problems for the Murray River. Whilst these fish are not dangerous to Australian wildlife, they are bottom-feeders and so muddy the waters of the river, as well as uprooting plants along the edges of the water and causing erosion of the riverbanks.

Of further environmental concerns to the Murray River, more so than the Darling, are man-made changes to the river. The locks, weirs and barrages which enable travel by watercraft up and down the river also change the natural flow of the river, and have therefore changed the ecosystem and environment of the river. Campers, holiday-makers in houseboats and others engaging in water sports, as well as land-developers, all have a detrimental effect on the Murray River.

Some of the issues surrounding the Murray River system, along with rising salinity levels in the lower reaches and lakes, are low water flows, equitable allocations for licence holders in all states, and plans by the SA government to allow seawater into the lower lakes or to regulate the flow by installing weirs to prevent the waters reaching the lower lakes. Communities in the areas around the lower lakes have vigorously defended the plans.