The Department of Water and Environmental Regulation assesses and monitors water quality in order to manage these valuable resources. We use a range of indicators to assess condition – the South West Index of River Condition (SWIRC) brings a large number of these indicators together into a single tool for assessing river condition in south-west Western Australia.
The SWIRC provides:
- a suite of standardised methods for collecting field and desktop data
- a suite of protocols for analysing field and desktop data, including a standardised system for scoring river condition.
The SWIRC covers a range of condition indicators across six key ecological themes representing ecological integrity: aquatic biota, water quality, fringing zone, physical form, hydrological change and catchment disturbance. Refer to the diagram below.
The SWIRC tool is very flexible where we can tailor our river condition assessments to suit individual circumstances. We can use all the indicators in the suite to generate a comprehensive assessment of river condition, or we can choose to focus our assessment on a sub-set of indices to answer specific questions (for example, when assessing summer refuge pools we focus on water quality and aquatic biota to see how they respond to reduced flows during hot weather).
The SWIRC includes a standardised system for scoring each indicator. This allows the results to be compared between river systems across south-west Western Australia. The scoring system complies with the national Framework for the Assessment of River and Wetland Health, and can be used to generate data for national comparison and reporting purposes.
The scoring protocols are based on a reference condition approach. Each score provides a measure of the departure of the observed values from expected values. The expected values are those typically anticipated under minimal disturbance conditions, and can be derived from historical data, data from minimally disturbed sites or expert opinion.
Details about the development of the SWIRC and the standardised methods for data collection analysis (including scoring) can be found on our Healthy Rivers website.