Water quality in urban rivers : a case study for the Hawkesbury-Nepean River system in Australia

Rivers are the main water sources for drinking, irrigation, recreational and industrial uses in many inland areas around the globe. Although river water accounts for only 0.0001% of the total water on earth, this is one of the main sources of fresh water for human consumption. Rivers are major carriers of nutrients from catchments to sea. In many countries around the globe, river water quality has been threatened by anthropogenic activities (e.g. urbanisation, intensive agriculture and industrialisation) as well as by the changes in climatic condition. A comprehensive assessment of river water quality is essential to safeguard river health. In this chapter, water quality of the Hawkesbury Nepean River System (HNRS) in New South Wales, Australia is investigated. The HNRS is one of the most important river systems in Australia, which provides drinking water to over 4.8 million people in Sydney. Water quality data from 9 monitoring stations are used in this study. It is found that water quality at all the 9 stations fall under either ‘poor’ or ‘marginal’ states based on the Canadian Water Quality Index (CWQI). None of the stations fall in the category of ‘good quality’ water. Further studies are recommended to investigate the underlying causes of the pollution and formulate management strategies to improve the water quality of the HNRS in near future.