Langat River is 180 km length has a total catchment area of 2,350 km². The Langat River is classified as Class II in the upstream, and as the water flows downstream the quality degrades to Class III and IV. This degradation is caused by the rapid and uncontrolled urbanization in the contributing catchment of the river. The characteristics of the river and its contributing catchment are modeled using Model for Urban Stormwater Improvement Conceptualisation (MUSIC) in order to rehabilitate the river and enhance its Water Quality Index (WQI) to Class II. The historical rainfall data was obtained from DID for the period from 1974 to 2012. This paper presents the effects of various BMP Components on rehabilitating the water quality of the river. In addition, the minimum amount of river flow required for protection of the habitats and the river's ecology has been assessed during the dry seasons. The outcomes of this study suggest the most appropriate Best Management Practices that can be used as solutions for the river's rehabilitation. Simulations and modeling result found out that a configuration of wetlands, bio-retention systems and ponds are capable to reduce pollutants loadings such as TSS, TP and TN by 85.1%, 69.1% and 37.5% respectively