In Brief | Inland water
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
This is a summary of Australia state of the environment 2011, which is an independent report presented to the Australian Government Minister for Sustainability, Environment, Water, Population and Communities by the State of the Environment 2011 Committee
Pressures of past human activities and recent droughts are affecting our inland water systems.
Most of the ongoing impacts on Australia's inland water environments are legacies of our historical land use, pest and weed introductions, and water resource development. In northern and remote Australia, human impacts have not significantly affected ecosystem function; in most southern regions, inland water ecological processes have changed substantially since European settlement and ecosystem function is significantly affected. The populations of many native species have declined. During the past decade (longer in some areas), the southern half of the continent experienced a drought of unprecedented duration and extent, which dramatically changed inland water environments, and there is evidence that this partly reflects a changing climate.
Climate change poses our greatest future threat.
The main risk to inland water environmental health that remains poorly mitigated is the likelihood of a drying and warming climate in our southern catchments and warmer temperatures across Australia. Current water–sharing rules tend to favour water entitlement holders over environmental flows in dry times. This means water is allocated for human use in preference to allowing water to stay in inland water systems. Managing for extreme conditions is emerging as a vital issue as the implications of a changing climate become more certain.
Meeting our water needs will be a critical challenge.
Demands for water will increase as Australia's population grows, and withdrawing water changes our inland water ecosystems. However, increased demand could be met without taking much more fresh water out of the environment (but potentially with other environmental costs, including increased energy use associated with desalination or wastewater recycling). Reduced water use will also play a part—Australia's water consumption fell 25% from 2004–05 to 2008–09.
Withdrawing water for other uses changes our inland water ecosystems.
Almost every inland ecological system in Australia is either permanently or seasonally limited by a shortage of water. Permanently withdrawing (abstracting) water from these systems will inevitably change their character in some way and degree. Conversely, this same water–limited ecology and our highly variable climate make these systems relatively resilient to small or short–term reductions in water availability.
The past decade has been Australia's most ambitious period of water policy reform.
All states and territories have now committed to the principles of the National Water Initiative. This commitment includes providing secure water for sustaining the environment. In addition, establishing an efficient and effective water market model will mean that prices will reflect the scarcity of water in Australia and water should flow to the economic, social and environmental uses of highest value.
Remediation of catchment water quality is not yet well managed.
While water abstraction pressures on inland water environments are becoming better managed (and, in places, alleviated), there is less monitoring, coordination and effort applied to the remediation of catchment water quality. Planning and management of these two dimensions of catchment health are still largely separate and could be coordinated and improved.
Better understanding is needed about how well ecosystems can withstand changes in water regime.
Except for the south–west corner of the continent, the southern drought ended in late 2010 with widespread flooding. Monitoring of river and wetland ecosystem recovery following these floods will provide crucial insights into how inherently resilient these systems are.
Many of Australia's inland water environments are in a degraded condition. In southern Australia, and particularly the Murray–Darling Basin, this is the result of relatively high levels of water resource development, compounded by an extended drought. During the past decade (longer in some areas), the southern half of the continent experienced a drought of unprecedented duration and extent. This dramatically changed the character of inland water environments.
Except for the south–west corner of the continent, this drought ended in late 2010 with widespread flooding. The recovery of river and wetland ecosystems following these floods will provide crucial insights into how inherently resilient these systems are—if this recovery is appropriately monitored. In south-western Australia, the current drought has led to a decline in river and wetland health as a result of low flows and high stream salinities (from lack of dilution). Northern Australian and Tasmanian inland water environments are generally in good condition. Nutrient levels in guidelines for fresh water are exceeded in all metropolitan areas and most areas of intensive agriculture. Monitoring of water quality, and interpretation of trends and causes, are inconsistent and sparse. It is therefore not possible to identify improving trends resulting from improved land practices.
Ecological processes have been altered to some degree across most parts of the continent. For much of northern and remote Australia, these changes are not significantly affecting ecosystem function and, with a few exceptions, there is little evidence that populations of aquatic species are declining. In most southern regions, inland water ecological processes have changed substantially since European settlement, significantly affecting ecosystems and causing declines in many native species populations.
Much of the pressure on our inland water environment is a legacy of the past—the clearing of native vegetation in catchments, the intentional or accidental introduction of weeds and pests, and the drainage of wetlands. These have moderate, ongoing consequences at the national scale.
Extensive land clearing has greatly decreased over the past 30 years, but urban expansion continues to affect wetlands and streams on the urban fringe, resulting in increased diffuse pollution and loss of habitat. Progress has been made towards controlling some of the serious weeds affecting inland water environments. The westward spread of cane toads across northern Australia is affecting systems in this region, and introduced fish species continue to have heavy impacts on aquatic ecosystems.
Although there is only limited capacity to reverse many historic impacts, there is reason to believe that projected population and economic growth can be significantly decoupled from future pressures on our inland water ecosystems. Australians are using less water, and while our rising population will increase demands for urban water, this is likely to be met without taking proportionately more fresh water out of the environment.
Progress towards restoring some environmental flows and plans by metropolitan water utilities to reduce future additional demands on freshwater resources are positive changes with respect to the pressures from water abstraction from the natural environment. The breaking of the extended drought in south–eastern Australia has provided much–needed flows. Nevertheless, the long–term environmental health of many southern Australian systems remains compromised by the amount of water abstracted for use. Surface water and groundwater overuse, with major consequences for local inland water environments, is likely to continue in many areas of southern Australia until the principles of the National Water Initiative are fully implemented and adjustments to abstraction levels are made. Systems in northern Australia generally have a low level of environmental pressure due to water abstraction.
There is compelling evidence that the ongoing drought (since 1975) in south-west Western Australia is partly related to human-induced climate change. It is almost certain that Australia's climate is continuing to change and that this will, if unmitigated, change water balances, flow regimes and inundation patterns of floodplains and wetlands. This is of great concern, because the implications will be major and widespread if the risk is not managed.
Using water from our environment is fundamental to our sustainability as a society. We have had an ambitious decade of water policy reform with all states and territories committing to the principles of the National Water Initiative. This initiative is designed around a market, regulatory and planning–based system to manage surface water and groundwater resources for rural and urban use in a way that optimises economic, social and environmental outcomes. This commitment includes provisions of adequate water for sustaining the environment.
Our understanding of the pressures on inland water ecosystems is good, and tends to be reflected in planning. Planning of water supply to take into account environmental needs and climate change is excellent for metropolitan areas, which are increasingly taking the approach of 'water security through diversity'. Examples are emerging of significant local or regional improvements in environmental flows or water quality.
However, strong empirical science on the quantitative relationship between flow regimes and ecosystem response or health is widely lacking, and this is hampering planning. Planning is incomplete for many water resource areas and uneven for water quality recovery. Significant investments are being made in recovering water for environmental flows, but the investment in improving water quality is small relative to the size of the challenge.
Processes for planning and management generally fail to meet expectations for consultation to allow Indigenous input, as agreed under the National Water Initiative. Public reactions to the Guide to the proposed Basin Plan for the Murray–Darling Basin highlighted the need for additional consultation.
Although the capacity to reverse many historical impacts is limited, there is reason to believe that projected population and economic growth can be significantly decoupled from future pressures on our inland water ecosystems. Mitigating the risks to inland water ecosystems arising from a changing climate will be far more challenging and may not be entirely possible. With some additional management intervention and investment, the inland water environment is likely to remain in generally good condition in northern Australia and in poor, but potentially improving, condition across much of the south, with only limited regions showing continuing serious deterioration. Much of the potential for improvement relies on adjusting future levels of water abstraction to meet environmental flow requirements, in a future that is likely to be drier in the south due to climate change.