A guide to water management in the Murray–Darling Basin

Section 1 of 5

Why water in the Murray–Darling Basin needs to be managed

Water in the Basin must be managed to sustain the river system and maintain water quality. Water management means that water is safe and can continue to support local communities, businesses and industries, Australian agriculture, and unique ecosystems.

When water is well managed it is:

• safe for humans to drink
• safe for other uses such as farming and recreation
• used sustainably
• delivered to where it needs to go
• shared fairly between those who need it, including the environment.

Water management constantly adapts in response to the latest scientific research and new information.

There are many demands on water in the Murray–Darling Basin. Since European settlement, people have dramatically changed the land, using it for farming and mining, and building cities, towns and roads.

We use far more water than we used to even a few decades ago. But the amount of water that comes from rain or groundwater hasn’t increased with us – in fact, due to climate change, it has decreased.

Section 2 of 5

An overview of water management

To the MDBA and the organisations it works with, ‘water management’ means the work that needs to be done to make water safe and get it to those who need it.

Water management includes:

• dividing water fairly and sustainably by calculating water availability and allocating water to entitlement holders within the limits
• making sure water gets where it needs to go so that human and environmental needs are met through river operations, including storing water for future needs and delivering water
• making sure water is safe for people, plants and animals by monitoring, evaluating and maintaining water quality
• making sure the water market is fair by developing, complying with and enforcing water trading rules
• making sure the river system is as healthy as possible by allocating water for the environment.

All water management activities require careful planning based on science and research. River operators make daily decisions based on the best available science, monitoring and modelling to manage the waters of the river.

You can read more about how these different aspects of water management work in the Murray–Darling Basin in section 4 of this guide.

How responsibilities are divided

The MDBA was established to manage the Basin as a connected system. The MDBA is responsible for:

• coordinating how the Basin’s water resources are managed, considering the health of the Basin as a whole
• calculating how much water is in the River Murray system and informing New South Wales, Victoria and South Australia of their ‘share’
• delivering water to entitlement holders in the River Murray system
• managing water in most of the River Murray system
• maintaining water infrastructure in the River Murray system
• implementing the Murray–Darling Basin Plan.

The states have agencies and authorities to manage water in their states. Their responsibilities include:

• allocating water to entitlement holders
• managing water that isn’t managed by the MDBA
• maintaining dams and water storages outside the River Murray system
• developing formal plans about how they will manage water to help them comply with the Murray–Darling Basin Plan.

Some responsibilities are shared between the MDBA and the states such as:

• delivering water to entitlement holders
• monitoring and maintaining water quality
• making decisions about water for the environment.

The Commonwealth Environmental Water Office was created to manage water for the environment. The Commonwealth Environmental Water Holder is responsible for:

• deciding the best way to use the water for the environment that is owned by the Australian Government.

The Australian Government Department of Climate Change, Energy, the Environment and Water is responsible for:

• buying water from entitlement holders and investing in more efficient irrigation so there is more water available in the system to keep rivers, lakes and wetlands healthy. This is called ‘recovering water’.

The Inspector-General of Water Compliance is responsible for:

• oversight of water management in the Basin and inquiry powers to investigate the implementation of the Water Act, the Basin Plan and intergovernmental agreements, including the Murray–Darling Basin Agreement.

Different approaches to water management in the northern and southern Basins

The northern and southern Basins have very different climates and landscapes.

In the southern Basin, the natural highs and lows of the land make it easier to store water and release it in a controlled way, so that it gets to people and places when they need it. There is generally more rain in the southern Basin, so more reliable predictions can be made about future water availability.

The northern Basin is mainly flat, with few hills or mountain ranges. This means that there are fewer low points in the land where water naturally collects in rivers or lakes. The water in the northern Basin moves slowly, in wide, shallow rivers and evaporates more quickly. As well, there are fewer places to store large amounts of water. All these factors mean that water in the northern Basin is regulated and managed differently to that in the southern Basin.

The boundary of the Murray–Darling Basin, including the boundaries of the northern and southern basins.

Calculating water availability and allocating water

Water in the Murray–Darling Basin is allocated to water entitlement holders. Water management includes calculating how much water is available for human consumption, the environment and industry so water can safely be taken from the river.

Each state has its own rules on how entitlements and allocations work. This is because the environment, agriculture, population and rainfall differ from state to state, and so the demand for water also varies from one location to another.

Who does what

The MDBA is responsible for calculating each state’s share of water in the River Murray system.

State governments allocate water within each water catchment, depending on how much water is available. The MDBA is not involved in deciding on the amount of water to allocate to entitlement holders.

• Learn more about how entitlements and allocations work

Monitoring and maintaining water quality

Water quality can be affected by many different environmental factors and weather events. Algal blooms, blackwater events, acid sulfate soil and salinity can all make water less safe for humans, plants and animals.

Who does what

The MDBA isn’t responsible for maintaining water quality, but it can sometimes help by releasing water to dilute saline or acidic water, or to try to prevent blackwater events and fish deaths.

The MDBA also monitors water quality in the River Murray system. Water samples are regularly collected from 28 sites along the River Murray and its tributaries in New South Wales, South Australia and Victoria. The data recorded from these sites includes:

• levels of chemicals and organisms in the water
• acidity
• temperature
• turbidity.

This data helps the MDBA:

• assess how human activity is affecting the river
• identify sources of pollution
• respond to algal blooms and blackwater events
• make decisions about when to release water
• make decisions about how to improve water quality
• keep long-term records.

The MDBA also manages salt interception schemes along the River Murray, which help prevent too much salt from entering the rivers.

State governments, in partnership with the Australian Government, are responsible for maintaining water quality. Depending on the location and circumstances, ways of managing water quality include:

• releasing water to dilute saline or acidic water
• installing water aerators or releasing extra water in areas where water is low in oxygen
• treating water to combat algal blooms
• installing and maintaining salt interception schemes to prevent too much salt from entering rivers.

State water resource plans

By agreeing to the Basin Plan, all Basin states have made a commitment to developing and improving sustainable water practices. Water resource plans are developed by each state government to set out how it intends to use its share of water to comply with the rules in the Basin Plan.

The Basin Plan specifies that the rivers of the Basin must be managed as a connected system. This includes the tributaries flowing into the main rivers. States’ water resource plans must address specific requirements on connectivity, including identifying the connections for that particular catchment, and setting out how these connections will be managed.

The plans specify:

• how water will be used at a local level
• new limits on the amount of water that can be taken from the system
• the amount of water allocated to the environment
• how water quality standards can be met.

Each state government is responsible for complying with their water resource plans and accounting for the water that is taken from the system.

Water resource plans are a requirement under the Basin Plan and must be submitted to the MDBA. The MDBA makes sure the states comply with their water resource plans and checks entitlement holders are taking only the water that has been allocated to them.

Section 5 of 5

Planning for the future: Sharing responsibilities under the Basin Plan

The Murray–Darling Basin Plan was created to improve the health of the Basin so that future generations can be sustained by its resources. It sets out how the MDBA and the states should work together.

The way water is managed changes over time

Water management is an evolving process. The way water is managed in the Basin has changed greatly over the past century, and will continue to change in the future. Climate change, the demand for water and the changing health of the environment will all influence how water is managed.

There is a continual cycle of planning, managing, monitoring and evaluating so that water is always managed in the best way possible and changes can be made.

Regular monitoring and evaluation includes consulting with communities, industry experts and partner governments.

Working together for sustainable future

Building a sustainable future is everyone’s responsibility. The MDBA and state and federal governments work together to set goals and meet them using water sharing plans and water resource plans.