River and wetland health assessment – national framework

AWR 2005 has developed a national framework that can form the basis of national river and wetland health assessments, and has the capacity to bring together results of existing broad-scale assessments conducted at state, territory and basin scale.

Framework for assessment of rivers and wetland health (FARWH)

• AWR 2005 has developed a new framework for the assessment of river and wetland health that can be applied to a range of scales, including surface water management area’s to deliver a national overview. The framework analyses data for six key criteria:
  • physical form
  • water quality
  • aquatic biota
  • hydrological disturbance
  • fringing zone
  • catchment disturbance.
• Results are aggregated and ranked in classes between zero (severely degraded) and one (pristine), and individual criteria can be displayed graphically if required.

The function of the FARWH is to bring together in an assessment, related elements of river and wetland condition – the approach has been informed by our understanding of linkages between catchments, river and wetland habitats, and their aquatic biota.

• The new framework was tested successfully on Victorian and Tasmanian data. Additional trials are required in other states and territories, and further development is necessary for use of the framework in wetlands. It is not intended that the framework replace existing assessment systems, rather it aims to provide a system of assessment for other jurisdictions based on and thus equivalent to those already in use.
• In the Victorian and Tasmanian trials, water management areas exhibiting a lower level of overall condition include the Moorabool, Loddon, Campaspe, Avoca, South Gippsland and Hopkins water management areas (Victoria) and the Jordan water management area (Tasmania).
• Comparison of the river health data with the information on diversions, extractions and entitlements for the Tasmanian and Victorian data validates the expected response that increasing diversions and extractions are correlated with declining river health.

Snapshot of river and wetland health assessments

Based on the 2000 study of river condition in the intensive land use zone by the National Land and Water Resources Audit, the following observations can be made:

• Of the river length that was assessed across Australia, more than 80 per cent was affected by catchment disturbance. Reaches in Tasmania and the Northern Territory were considered the least affected by catchment disturbance.
• In about 20 per cent of the regulated river length that was assessed, the flow regimes were largely unmodified from an ecological perspective.
• Stream habitat was modified from pre-European conditions in more than half of the river length that was assessed. Degradation of the habitat was considered to be largely because of changes in the sediment loads that alter channel morphology and loss of riparian vegetation. Scores for habitat were lowest in New South Wales, South Australia and Western Australia.
• Nutrients and suspended sediment loads were higher than pre-European settlement conditions in more than 90 per cent of the river lengths assessed, and are substantially modified in at least one third of the river length that was assessed in every state and territory, except Tasmania.

In the Murray-Darling Basin, the following key observations were made, based on the 2001 Assessment of Murray-Darling Basin River Health Condition:

• Ten per cent of river length was identified as severely impaired, having lost at least 50 per cent of the types of aquatic invertebrates expected to occur there.
• More than 95 per cent of the river length assessed in the Murray-Darling Basin had an environmental condition that was degraded and 30 per cent was substantially modified from the original condition.
• Most reaches in the central and western part of the Murray-Darling Basin were moderately modified.
• All groups of reaches in the Basin had disturbed catchments and modified water quality.
• Many parts of the Basin were threatened by multiple stresses, principally land use changes, damaged riparian vegetation, poor water quality, increased bedload, and modified hydrology.

From the south-east Queensland Ecosystem Health Monitoring Program (EHMP 2005), the following key findings are apparent:

• Major changes in freshwater ecosystem health during 2004–05 were not detected.
• Natural variation appears to account for the minor changes in indicator correlations across the different years of assessment.

Collecting water quality data for assessing river health
Image by Axel Allgaier, sourced from SKM

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