Abstract: Hydrological study was carried out at Bukit Tarek F.R., Kerling Selangor with the establishment of forest plantation. Seven years of water quality data were analysed to determine the effects of forest clear felling and buffer zone to the stream flow. Three experimental catchments: C1, C2 and C3 were established for monitoring the changes. C1 was a control catchment, C2 was clear felled and the residual trees were left on the site, while C3 was also clear felled but the site was burnt prior to forest planting. The parameters observed were pH, conductivity, turbidity and colour. The values of each parameter increased during and after clear felled. The values of water quality in C3 were higher compared to C2. During clear felling, catchment C3 indicated that pH increased was about 1.6%, conductivity 49.2% and turbidity 350.8% while, catchment C2: pH increased 0.96%, conductivity 25.7% and turbidity 279%. Parameters in control catchment (C1) did not show significant changes fo...