This slide presentation outlines a study on the fate of ammonia in groundwater treatment. Aspects of the study included: ammonia was recently found in groundwater wells; Research and Technical Practices Committee conducted a study from Sept. 27, 2003-February 4, 2004; 123 groundwater systems sampled for ammonia-N (187 wells); and, 118 samples of 187 were 0.15 mg/L NH3- N or greater. Ammonia's reaction with chlorine is outlined, along with the practice of nitrification, the process by which bacteria can utilize ammonia and nitrite as electron donors, sampling, types of treatment, and results for ammonia, nitrate/nitrite. Observations include: all plants sampled have some ammonia in their groundwater; one plant is utilizing natural ammonia to form chloramines; and, all plants sampled are experiencing formation of nitrate in the treatment process. Includes tables, figures.