Total bacterial density was investigated in the main stream and tributaries of the Kyongan Stream and inlet parts of Paltang Reservoir from September 2000 to February 2001 by acridine orange direct count (AODC) method. Total bacterial number in the Kyongan Stream was mainly under influence of the effluent discharge of sewage wastewater treatment plant (SWTP) located in the upstream or downstream. Decreasing rate with water flowing distance (km) in the main stream is $0.13;{ ime};10^6$ cells/ml, and it was estimated to much accumulating quantity on the stream bed during transport to downstream. Average values of total bacterial number in September${sim}$October, November and December${sim}$February were range $1.74{sim}3.10{ ime}10^6$, $1.86{sim}7.30{ ime}10^6$ and $4.56{sim}8.75{ ime}10^6$cells/ml, respectively, and were high at low temperature than that of high temperature period. Total bacterial number was more abundant at below $10^{circ}C$ with $2.1{sim}3.0$ folds than at above $10^{circ}C$. Water quality by total bacterial number was classify to eutrophic and the potential of wastewater treated effluent for the microbial contamination assessed to very high. The results of this study indicate that the management of point source, SWTP effluent, is urgent to mitigate bacterial impact of Paltang Reservoir as well as the Kyongan Stream.