Evaluation of Water Quality Management Policies for the Yarra River Basin

Other book title: Proceedings of the 25th Hydrology and Water Resources Symposium, 6-8 July 1999, Brisbane Convention and Exhibition Centre, Queensland, Australia. The Environmental Protection Authority of Victoria implemented a new water quality management policy for the Yarra River and its tributaries in 1997, with further revision scheduled for the year after 2002. This current policy limits major point source pollution discharges to uniform effluent concentrations of 10mg/l BOD, 10mg/l suspended solids, 10mg/l total nitrogen and 1mg/l total phosphorus. In addition to improvements in point source effluent quality, reduction of non-point source pollution loading is also recommended to attain some pre-set objectives for water quality. Furthermore, the policy encourages polluters to investigate innovative and cost-effective options of pollution management. Therefore, this study involves the investigation of the most effective management strategies for the Yarra River in terms of nutrient control. Nutrients in the Yarra River are simulated using The Enhanced Stream Water Quality Model (QUAL2E). Preliminary results suggest that some alternative management scenarios will produce similar or lower nutrient concentration in the Yarra River compared with the current policy. Furthermore, point sources have more pronounced effect on the stream quality during low flow periods, while diffused sources are relatively more important during high flow periods.