|The 25th Street Combined Sewer Overflow was analyzed for total coliforms, Escherichia coli, antibiotic-resistant coliforms and E. coli, and routine water chemistry. The objectives of this study were to enumerate antibiotic resistant bacteria near a CSO, determine the impact of a small quantity CSO on Ohio River water quality during a storm event, and to correlate antibiotic resistance with conventional water quality measurements. The data indicate that resistant bacteria exist in both river water and wastewater, and that this CSO can not be identified as a source of resistant strains. Rain events do cause a detectable and transient change in water quality due to CSO release. Smaller rain events had a prolonged negative impact on river water quality relative to large rain events due to cleansing of the CSO by large volumes of stormwater. Biological indicators were found to be better markers of CSO impact than standard chemical analytes.