N. S. M. Noh WATER POLLUTION & WATER QUALITY ASSESSMENT BASED ON WATER QUALITY INDEX METHOD FOR JOHOR RIVER
The Johor river basin is currently facing degradation of its water quality. Johor River is divided into 20 sub-basins where the upstream portion of the basin is still covered with natural forest and swampy area. Meanwhile, the midstream part is a mixture of landuse and the downstream region populated mainly with industrial activity. This study aims to investigate the water pollution and water quality status using the water quality index (WQI) method. The Water Quality Index (WQI) is used to indicate the level of pollution and the corresponding suitability in terms of water uses according to the National Water Quality Standards for Malaysia (NWQS). This study also considers the proposed New Water Quality Index (NWQI). Results show that the upstream part of the Johor River basin is dominant by Class II and Class III. River status at the midstream part gradually change to Class III and degrade continuously to Class IV and V as it goes towards downstream. The high development of industrial activities at the downstream part causing the river polluted with the receiving of treated and untreated industrial effluent.