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Publications archive - Ecologically Sustainable Development

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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Are We Sustaining Australia? Report Against Headline Sustainabilty Indicators

Environment Australia, 2002
ISBN 0 642 54771 8


Value 20: Freshwater health

Rationale for inclusion of issue

Freshwater ecosystems provide economic and environmental services crucial to all life and well-being in Australia, both now and in the future. Water, of suitable quality and quantity, delivered at appropriate times, is vital to the ecological health of aquatic, riparian, and terrestrial ecosystems. It is also an essential economic resource that underpins Australia's economic development.

The condition of river systems represents an integration of land use activities, and a major input to the estuarine and marine environments. Safeguarding freshwater systems is therefore essential to protecting a range of ecological processes (Core objective 3) and economic prosperity which, in turn, are essential to the welfare and well-being of future generations (Core Objective 1), as well as providing for inter-generational equity (Core Objective 2).

Indicator 23

Proportion of assessed sites which are with high in-stream biodiversity, based on macro-invertebrate community structure assessed using AusRivAs (as at April 2001)

60%

Source: National River Health Assessment 2000-2001

Rationale for selection of indicator

The agreed indicator is the River Condition Index being developed by the NLWRA. It will provide an integrated assessment, incorporating sub-indices relating to hydrology, water quality, physical habitat and catchment condition in addition to AusRivAs biota data (where available). However, work on this index is incomplete.

Macro-invertebrate assemblage data are used as an interim indicator. These represent the findings from the River Health Assessment (River Condition - AusRivAs Band Scores) and are the only nationally consistent freshwater biota data set available at present.

Aquatic macro-invertebrates are very useful indicators for biological monitoring. They are generally visible to the naked eye and are commonly found in streams. They are an important source of food for fish and include worms, snails, water boatmen, yabbies, dragonflies, stoneflies, and mayflies. They are widespread, easy to collect, relatively immobile, and most importantly, they reflect the aggregate of impacts of environmental changes impacting on the stream ecosystem over a six month period.

Explanatory and elaborative information

The interim indicator describes the number of assessed sites found to be in good condition (that is, either more biologically diverse or having similar biological diversity to the reference sites), based on the presence/absence of families of aquatic macro-invertebrates.

Data is derived from family-level macro-invertebrate bioassessments, based on National River Health Program information provided by the States and Territories to the NLWRA and to the national State of the Environment Report. The interim indicator value is based on 3112 test sites and 1487 reference sites. Test sites were selected on the basis of "management concern", and included a variety of sites representative of the types of waterways, land and water uses, and impacts in each river basin.

The interim indicator Value does not include reference sites as their inclusion would unreasonably bias the results. Moreover, the point-based nature of the assessment data cannot necessarily be readily extrapolated to the entire river basin or drainage division. Nonetheless, the data provides a comprehensive assessment of river health across Australia and can be effectively and efficiently utilised to identify trends in river health over time.

AusRivAS consists of a series of bioassessment protocols and state-specific mathematical models which use field data to predict the aquatic macro-invertebrate families that would be expected to be present at a test site if it were in "reference" condition and free from human impacts. River health assessment scores are based on the differences between the number of aquatic macro-invertebrate families found at test sites and what was predicted to have occurred there from a set of reference sites with similar geographic, physical, and chemical features. The models used to determine these scores have been developed using habitat information and macro-invertebrate surveys conducted at over 1500 carefully selected, pristine or least impacted reference sites.

The data indicates that 5% of the sites assessed using AusRivAS were more biologically diverse than expected, while a further 55% had similar levels of biodiversity to the reference sites. 31% of sites were significantly impaired. 8% of sites were severely impaired. 1% of sites were found to be extremely impaired. In general terms, the interim indicator shows that approximately 60% of the assessed sites are either more biologically diverse or have similar biological diversity to the reference sites and were therefore likely to be in good condition. The indicator also shows that the remaining 40% of assessed sites have lost around 15% or more of their expected biodiversity.

Sites Assessed Using AusRivAS (all States and Territories, 1994 - 1999)

Number of Test Sites Number of Reference Sites Total
3112 1487 4599
 
Number of Sites per Band
X A B C D Total
more biologically diverse than reference similar to reference condition significantly impaired substantially impaired severely impaired test sites
154 1702 963 254 39 3112


Interim Indicator: River Health River Condition - Sites per AusRivAs band (Interim NRHP River Health Assessment, all states and territories, 1994-1999.

Notes:
1. As at 9 April 2001.
2. Based on information provided by states and territories for National Land and Water Resources Auditing and national State of the Environment Reporting.
3. State data and information collated and analysed by the CRCFE.
Source: National River Health Assessment 2000-20001

Supplementary indicators