Application of a composite water qaulity index to assess the health of water sources

The generic quality of naturally occurring water sources can be described using water quality parameters that describe the physical, chemical and biological conditions of the water. Each of these parameters reflects different characteristics of the water body and the overall health can be assessed by comparing threshold values detailed in water quality guidelines. The aim of the paper is to identify the suitability of a single composite Water Quality Index (WQI) to assess overall environmental health of a water body. The study uses 14 years of water quality data from four sites along the Dandenong creek in southeast Melbourne in Australia. The water quality parameters are available at monthly intervals. The WQI was calculated and the results from its application were used to identify the variation in water quality when water flows from pati forested upstream, rural catchments to urbanized downstream catchments. E.coli, Turbidity and Dissolve Oxygen were the most sensitive parameters in the composite WQI. Results from this preliminaty assessment could lead to more focused detailed investigation studies if ce1iain enviromnental receptors are shown to be at risk.