This paper presents the methods and results of a comprehensive water quality sampling program of a small section of United Water New Jersey's drinking water distribution system. United Water New Jersey is located in the northeast corner of the state of New Jersey and serves 60 communities in Bergen and Hudson counties. The sampling results revealed a localized area of excessive chlorine decay, high heterotrophic counts, and evidence of significant nitrification all driven by substantial nutrient loading. With biodegradable organic carbon levels of 1.75 mg/L and reduced nitrogen levels of over l mg/L, heterotrophic and nitrifying bacterial growth overpower residual chlorine in this local area even with 3.00 to 3.50 mg/L of monochloramine entering the distribution system. Excessive chloramine decay is linked to nitrification in the distribution system. The results of this study led to hydraulic changes and other techniques that are helping to correct the above situation.