This study was conducted to evaluate the annual population variation and identification of antibiotic-resistant bacteria in the lower artificial Lake Geumgang from January to December, 2002. Samples were taken from the surface waters at 3 stations near the estuarine barrage. The results were as follows; the population densities of heterotrophic bacteria varied from 4.1±1.0×10² to 6.7±1.1×10³ cfu ml^-1 during the investigation periods. The population densities of antibiotic-resistant bacteria ranged from 1.5±0.7×10 to 4.3±0.3×10³ cfu ml^-1 for ampicillin; from 0 to 6.4±0.4× 10² cfu ml^-1 for chloramphenicol; from 0 to 2.8±0.3×10³ cfu ml^-1 for gentamicin; from 0 to 4.5±1.0×10³ cfu ml^-1 for kanamycin; and from 1.0±0.4 × 10 to 2.3±0.5×10³ cfu ml^-1 for streptomycin, respectively. Of the sixty isolates, 90% were Gram negative. Dominant genera by 16S rDNA analysis were identified Aeromonas spp. (14 strains), Bacillus spp. (6 strains), Enterobacter spp. (4 strains), and Stenotrophomonas spp. (6 strains). These strains were clustered into 12 groups based on relatedness by average linkage method. Of the 60 isolates, 85% had the resistance to ampicilin and 32% were shown resistance to more than 2 kinds of antibiotics.