To determine the role biofiltration in organic removal and taste and odor compound removal within the Moorhead Water Treatment Plant, a comparative two-year pilot scale study was initiated to determine the feasibility of replacing anthracite with granular activated carbon (GAC). To determine the biomass associated with the pilot system and the different media types, ATP tests and qPCR measurements for the 16S rRNA bacteria gene were made over the course of the study to evaluate the potential impact of biomass for organics removal. The data suggests that the ATP method may have resulted in under estimation of amount of attached biomass on GACs due to their adsorptive properties and was not effective for biomass monitoring. In addition, ATP was unable to correlate with organics removal within the system during summer months. In addition, analysis was conducted to determine the impact of Empty Bed Contact Time (EBCT) on removal of geosmin.