Why make a jigsaw puzzle of the lower Murray?

River red gums along the Murray feature in an evocative painting, “Barmah Forest”, set on canvas by Lin Onus in 1994. Scattered among the ancient trees are misshapen jigsaw pieces that have been lifted from the canvas and could not be fitted back into the big picture. The image of disrepair resonates for many environmental issues, including the present crisis near the Murray Mouth.

Drought has hit hard along the lower river, Lakes Alexandrina and Albert and the Coorong. Flows have dwindled, the lakes are receding and becoming more saline, acid sulfate soils are exposed around the shores, the river mouth would close but for constant dredging and parts of the Coorong have turned to brine. There is frustration for many, hardship for farmers and anguish for Ngarrindjeri people. There is concern about water supplies for Adelaide and rural towns, about the effects on the regional economy and, not least, the environment. The wetland ecosystem is on life support.

There have been many signs that a crisis of supply and demand was imminent. The first recorded closure of the river mouth in 1981 should have been a wake-up call, but instead allocations were increased, basin-wide. State and federal governments ought to be held to account, but our politicians have found it easy to renounce history, or to invoke the blame game with their colleagues and with other states.

As we respond to the immediate problems, let us not overlook the need for a more considered plan for the future. Let us not scatter the pieces of the jigsaw any further.

The South Australian government has responded to the Lower Lakes crisis by announcing several proposals, among them:

• a causeway and weir across the Murray at Pomanda Island, near the river’s entry to Lake Alexandrina, to provide a reserve water supply for Adelaide and rural towns;
• one or more weirs in the Goolwa channel to create a freshwater refuge in the area where Currency Creek and the Finniss River enter Lake Alexandrina; and
• a plan to introduce seawater to Lake Alexandrina.

There are also suggestions - so far without official support - to disconnect Lake Albert from Lake Alexandrina, and to pump hyper-saline water from the Coorong to the sea.

Each of these proposals, official and otherwise, deserves close scrutiny. All involve large-scale engineering interventions, and little effort has been made to evaluate alternatives.

Once a proposal has state-government endorsement it is referred to the federal Minister, who decides whether or not an Environmental Impact Statement is required. The protocol is determined by the federal Environment Protection and Biodiversity Conservation Act (1999).

The state government’s multiple proposals obscure an important point. The river, lakes and Coorong are a Ramsar Wetland of International Significance, according to a commitment that Australia made in 1985. It is a single wetland complex, containing parts that are inter-linked.

If those parts were isolated from each other, the region would lose most of its ecological integrity. If they are managed separately, the task of conserving the environment, according to the spirit of the Ramsar convention, will become immeasurably more difficult.

Natural resource management is founded in the science of ecology, where the first rule is that complex systems cannot be understood by dividing them into pieces. Ecology could claim to be “the science of the big picture”.