Saint Paul Regional Water Services (SPRWS) in St. Paul, MN experiences taste and odor episodes during the warm summer months. The taste and odor episodes were attributed to the production of geosmin by cyanobacteria growing in the chain of lakes used to convey and store the source water pumped from the Mississippi River. The current SPRWS treatment train, which includes lime softening, chlorination, and anthracite-sand filtration, is not effective at removing geosmin. Reasonable doses of powdered activated carbon (PAC) and potassium permanganate were not effective either. The objectives of this research were to evaluate the effectiveness of two alternative treatment processes for geosmin removal: (1) granular activated carbon (GAC) adsorption and (2) ozonation followed by GAC filtration.