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This paper presents the approach and methods used, and the outputs generated, in the derivation of numeric biological objectives for the protection of rivers and streams across Victoria, Australia. Biological objectives have been designed for inclusion in State government legislation for the protection of the State’s waterways. The objectives were developed using data from extensive macroinvertebrate sampling of multiple reference sites across the State. Regional variations are incorporated into the objective-setting process by using an a priori, macroinvertebrate-based regionalisation of the State. The objectives consist of four separate components, including a measure of diversity, two biotic indices and a measure of community composition. The objectives are designed for use across broad regions and any attempt to extend the system to subregional levels would require a careful consideration of the influence of scale upon the grouping of reference sites. [ABSTRACT FROM AUTHOR]

Dryland rivers occur over much of Australia’s inland and have some of the most variable patterns of flow in the world. Despite their dominance in terms of Australia’s river types, dryland rivers have not been the focus of the recent increase in research on indicators of river health, mostly owing to their spatial remoteness and relatively low levels of water resource development and human disturbance. Most rivers in arid and semi-arid regions are ephemeral, and only carry significant flows during the wetter months or following infrequent but intense rainfall events. It is not known which, if any, of the existing approaches to river health assessment can be used to accurately assess the health of these large ephemeral rivers. This paper considers why the standard methods for interpreting the currently-used indicators for river health may need to be adapted for variable systems and suggests the use of trends that recognise natural variation in indicator values for undertaking this. [ABSTRACT FROM AUTHOR]