Water reform is needed in the Murray-Darling Basin to deliver healthy rivers, strong communities and sustainable food and fibre production.
The use of Basin water resources has supported local economic growth but has also damaged the environment. A more balanced distribution of water is needed to ensure the long-term health of the Basin.
Without a healthy river, water quality deteriorates as salt and minerals build up in the system. Floodplains deteriorate, affecting their ability to sustain agriculture.
In an average year, 2 million tonnes of salt flows down the Murray-Darling. It is vital for the health of the Basin to flush out these salt and excess nutrients through the mouth of the river. A closed river mouth means less salt is exported from the Basin. Over the last decade the Murray Mouth has been closed for 4 of 10 years.
Salinity in the Basin damages agricultural production, imposes economic costs and affects the quality of drinking water. A 2003 study estimated the cost of salinity on water infrastructure and land in the Basin at $305 million per year.
In 2001, the Murray-Darling Basin Ministerial Council took a whole-of-basin approach to salinity management and adopted the Basin Salinity Management Strategy. A revised Basin Salinity Management Strategy was adapted by Council in November 2015.
Increased river flows will ensure that the River Murray can export salt through its mouth 9 years out of 10.
Reduced availability of water and changes to flow regimes has resulted in environmental decline
The Basin is important for biodiversity and supports a large number of plants, animals and ecosystems, including 95 species listed as threatened.
The volume of water that flows through Basin rivers is naturally low and far more variable than major international rivers. For example, the average annual volume of water flowing through the River Murray is less than the average daily flow of the Amazon River.
The combined effect of low levels of rainfall, slow flows and a generally flat topography mean that the rivers experience high levels of evaporative losses and are less able to accommodate efficient water storages.
Farmers, communities and governments in the Basin have made significant progress in using water more wisely, including adopting world-class irrigation practices and technology. However, overall, too much water is being removed from the Basin's rivers, wetlands and floodplains, resulting in long-term environmental decline.
Before development of water resources for consumptive uses, natural flows would produce regular medium floods, as well as seasonal dry periods. The system would be flushed duringhigh flow periods and low flows in summer would support other important environmental processes. Development in the Basin has reduced these natural fluctuations in stream flows. For example, before the restoration of environmental flows, environmentally significant sites below major storages only rarely benefitted from natural small to medium floods.
Both the reduced availability of water and changes to flow regimes has resulted in environmental decline. Native bird and fish numbers have been falling, algal blooms have increased and during the last drought the Basin experienced the world's largest recorded outbreak of acid sulfate soils.
These changes have also reduced the environment's ability to perform important services such as pollination, fish breeding, nutrient recycling and replenishment of soils.
Restoring regular flows to the Basin will improve environmental health and deliver benefits to all users
Restoring regular flows will deliver environmental, economic and social benefits.
Environmental benefits include:
- increased carbon and nutrient sources in-channel from more regular floodplain inundation
- (over time) increased population of native fish as a result of more high flow and inundation events
- increased nesting of endangered water birds as a result of more regular floodplain inundation
- lower salinity from more regular flushing of the system.
Economic benefits include:
- productivity benefits arising from the improved capacity of rivers and floodplains to provide ‘ecosystem services’ such as
- increased carbon and nutrient recycling leading to improved soil and water quality
- improved pollination and pest management through biodiversity
- groundwater replenishment
- a significant reduction in the economic losses associated with algal blooms and salinity
- growth in recreation and tourism industries generated by healthy rivers.
Social benefits include:
- improved capacity for river based recreation
- improvement in the quality of town water supplies
- improved fishing opportunities due to larger native fish populations.