Region at Risk: Murray Darling Basin

Risk: Murray Darling Basin : drought, over-allocation, conservation

Phil McNamara | Natural Heritage Manager, National Trust (SA)

The Murray Darling Basin occupies a vast area of south-east Australia, extending into Queensland, New South Wales, Victoria, South Australia and the Australian Capital Territory. It is drained by Australia’s three longest Rivers, the Murray (2530 km), the Darling (2740 km) and the Murrumbidgee (1690 km). The region is one of great diversity in natural environments, animals, plants and invertebrates. There are an estimated 30 000 wetlands that are essential breeding grounds for fish and other organisms. Wetlands are also important in absorbing, recycling and releasing nutrients, trapping sediment and mitigating the effects of flood and drought.

In a relatively short space of time, however, the environment of the Basin has changed significantly. Human occupation of the Basin dates back 40 000 years. While Aboriginal people changed the nature of the environment, the most profound impacts have occurred since European settlement. Early settlers began using the Murray as a highway to deliver supplies to towns and stations, and to carry wool and other products to markets. By 1900 the river trade had virtually finished having been superseded by railways that had grown out of Melbourne, Sydney and Adelaide. From this time the major rivers were used increasingly as a source of water for irrigation with Australia’s first irrigation settlement established by the Chaff ey Brothers in Renmark in 1887. Perhaps the biggest changes occurred between the two World Wars when weirs and locks were built to provide permanent waterways to increase water availability.

Today the river system is highly regulated. This has produced Australia’s most important agricultural region accounting for over 34 per cent of the gross value of agricultural production. It also provides drinking water to over three million people, one-third of which are outside the Basin. But irrigation is the largest user (95% of diverted water) and there has been a five-fold increase in water diverted from the River system since 1920 (now over 10 000 gigalitres on average each year)

While the regulation of our water resources and land clearance has been the backbone to irrigation industries, it has been at a cost, having increased salinity, nutrient and suspended sediment levels and reduced environmental flows. The result has been more saline water, an increase in algal blooms and changed habitat, threatening our natural plant, fish, animal and invertebrate populations. Over 95% of the Murray is now in a degraded environmental condition and native fish populations are at critically low levels.

The management of water resources (including water allocation) is a State responsibility, and this has made it difficult to address key challenges as the Basin embraces five different jurisdictions. Since the 1980s State and Commonwealth Governments have sought to improve coordination, largely through the Council of Australian Governments (COAG) which became the key policy forum for natural resource issues in the 19905.

The Murray Darling Basin (MDB) Agreement was signed in 1992 and put in place water sharing arrangements and a process for water management, establishing the MDB Ministerial Council and MDB Commission. In 2004 the National Water Initiative was signed in an attempt to address over-allocation, expand water trading and improve the efficiency of water management infrastructure. At the same time $500 million was committed over five years to return 500 gigalitres of water to the environment at six significant sites including the Coorong and Lower Lakes.

Despite these reforms and the urgency of the issues, the purchasing of water entitlements has been extremely slow. The current drought has exacerbated the situation with inflows into the river system at record lows in 2006 and 2007. In the longer term climate change is predicted to reduce inflows

by at least 1100 gigalitres annually. As a result there have been a variety of responses from State and Commonwealth Governments including a temporary reduction in allocations to industry, proposals for increased water storage, such as increasing the capacity of Mount Bold Reservoir in the Adelaide Hills, and to close many regulated wetlands. In South Australia, for example, 29 regulated wetlands have been closed despite theimportant role they play.

More recently, on 25 January 2007, the Commonwealth Government announced a National Plan for Water Security. The Plan, funded by an investment of $10 billion over ten years, aims to make rural water use sustainable by modernising irrigation infrastructure, purchasing allocations from willing irrigators and revising the cap on diversions. Perhaps most importantly the plan also proposes a new management structure where the Commonwealth government would take control of water management in the MDB, contingent on the referral of state and territory powers. Victoria, which uses over 30% of diversions, did not agree to the proposal and a revised plan was proposed. The new Commonwealth Water Act 2007 was passed giving effect to key elements of the revised plan. This includes the establishment of a skills based Murray Darling Basin Authority, responsible for preparing a basin-wide plan and setting sustainable limits on water diversions.

But in the absence of a full referral of powers by the State and Territory Governments the effectiveness of the plan, and the new Authority, are contingent on an intergovernmental agreement which is yet to be ratified by the States and Territories. In the simplest of terms, two things are needed to improve the health of the MDB River System and make water resources more secure: water entitlements must be bought, and environmental flows must increase.

In 2003 the Scientific Reference Panel for the Murray Darling Basin Commission stated that an annual allocation of 1500 gigalitres to environmental flows could deliver a healthy River Murray System. This is an achievable goal to work towards but does not mean simply buying back 1500 gigalitres from irrigators. It has to be real flows. Simply buying it back from irrigators would not necessarily improve the river system because in an average year irrigators are only using two-thirds of their entitlements. Therefore significant quantities of water entitlements must be bought to reduce the amount of diverted water. Those affected must be compensated for their loss.

The new Commonwealth Water Act 2007, the new Murray Darling Basin Authority and basin-wide plan are a step in the right direction but the failure of all States and Territories to agree, once again, has competing interests obstructing good decision making. The challenge of implementing an effective management regime for the rivers will be one of the great tests of our national maturity. It requires: a high level of technical skill but more importantly idealism and vision which values the common good over sectional interests. This will only happen if parliamentarians at the State and National level show leadership and if the general public make it clear they support the rehabilitation of the Murray Darling Basin.