The FUTURE of
t he MURRAY
he greatest challenge facing the survival of the Murray ecosystem today is
the rising underground water table and associated increasing salinity. This
T
phenomenon is due to the extensive irrigation network, where enormous
quantities of water are pumped from the river into channels to supply the vast fruit
bowl of the Murray Basin. The whole inland region of the Australian continent is an
extinct seabed. As the water table is raised, it brings the salt of this primordial sea
with it to the surface. Consequently, the dead lands and the salt pans have been
increasing. The results are most visible in the South Australian reaches of the river,
but it is a problem of huge and unsettling proportions, which affects an agricultural
area the size of approximately one-seventh of Australia and the food-producing
capability and environmental health of the whole nation. Added to this burgeoning
salinity of soil and water, is the problem of run-off containing, among other
contaminants, agricultural chemicals such as herbicides and pesticides.
Human interference with the natural water-flow equilibrium is another
environmental concern. Before irrigation, dams and locks, the red gum forests were
regularly inundated by the swelling rivers which breached their banks during the spring
and winter rains. The red gum forests are not just tolerant of short periods of regular
immersion, they are dependent upon inundation for growth and regeneration. Inundation
of the forests to a depth of around 1 to 1.5 metres was usual in four out of five years.
The waters are not just important for the trees themselves. Birds, particularly waterfowl,
depend on these wetlands during migration and breeding. They, along with other
animals, are part of the enormous and intricate web of this environment.
One way to counter the detrimental effects of human tampering with river patterns,
has been to release water from dams and mainstream regulators when water flow is
particularly high, thereby replenishing water in the swamps and lagoons. Water
replenishment is combined with the selection and felling of cull trees and thinning of
young growth. It has been found that the silvicultural technique of culling selected trees
evenly distributed throughout an area reduces the competition for soil moisture during
the dry conditions of summer, increasing both regeneration and advanced growth. Good
forest stewardship, which includes such beneficial techniques as broadcast burning prior
to May to put down a nourishing ash layer, aerial or manual seeding of areas in some
cases, and isolation of regeneration zones, has made substantial contributions towards
returning the forests to their former condition. These approaches have proven par-
ticularly valuable in the light of the uninformed and rapacious logging practices of the
past. Even in the early days of logging there was some awareness of the sense in
conserving Murray red gum forests. It was first recorded in 1869 when Crown Lands
Bailiff, Henry Stephenson, warned his government of the threats to red gums.
Fortunately some decisionmakers took note and acted. Within a couple of months of
Stephenson's letter, a tract of 19600 hectares was protected. It was not a lot, but at least
it was something.
overleaf : An old windmill from the Murray River region at rest in the heat at the Swan Hill Pioneer
Settlement, Swan Hill, Victoria.
above: An early morning mist greets the rising sun. In the foreground, the exposed tentacles of
red gum roots contrast with the gentle beauty of the scene.