Development and testing of an Index of Stream Condition for waterway management in Australia

1. An Index of Stream Condition (ISC) has been developed to assist broad scale management of waterways by providing an integrated measure of their environmental condition. 2. The ISC provides scores for five components of stream condition: (i) hydrology (based on change in volume and seasonality of flow from natural conditions); (ii) physical form (based on bank stability, bed erosion or aggradation, influence of artificial barriers, and abundance and origin of coarse woody debris); (iii) streamside zone (based on types of plants; spatial extent, width, and intactness of riparian vegetation; regeneration of overstorey species, and condition of wetlands and billabongs); (iv) water quality (based on an assessment of phosphorus, turbidity, electrical conductivity and pH); and (v) aquatic life (based on number of families of macroinvertebrates). 3. The ISC is intended for use by managers at state and regional levels and can be used to report on stream condition, assist with priority setting, judge the long-term effectiveness of rehabilitation programs and assist with adaptive management. The best available scientific information was used by a multidisciplinary group of scientists and managers to create a stream assessment procedure that can be used routinely by people with limited scientific training. 4. ISC development included trials in four catchments in Victoria, Australia. Over 80 stream reaches were assessed and the results were used to refine the ISC to improve the ease of measurement and ensure that outcomes met the expectations of users. The ISC is now available to be used more widely for reporting on stream condition.