In an effort to optimize their corrosion control strategy, a Lake Michigan water utility tested several phosphate inhibitors for their effectiveness to control lead. The objective of this research was to show through pipe loop testing, the impact of different forms and dosages of phosphate-based corrosion inhibitors on lead levels in the water. Furthermore, this study investigated the impact of seasonal temperature variations on lead levels and the role of deposition formation in corrosion control. Testing was completed using multiple pipe loop systems. Each loop was constructed of two 15- foot legs of 1-inch lead service line gathered from the utility's distribution system. To simulate distribution system flow, water flowed through the loops at 2 feet per second (ft/s) for 16 hours and then stagnated for eight hours. Samples were collected after approximately seven hours of stagnation. Several conditions were tested over a four year period. Overall results from the testing showed the following: orthophosphate levels can be optimized to maintain low lead levels while limiting the amount of deposition in the distribution system; orthophosphate was more effective than polyphosphate for controlling lead levels; orthophosphate alone was as effective as blended phosphate in controlling lead levels; lead levels were moderately impacted by temperature, lead levels increased at higher temperatures; the results show that once a phosphate layer forms on the walls of the pipes, temporary interruptions do not dissolve the scale, which provides the necessary protection against increased lead levels, a small or "maintenance" dose of phosphate appears to be sufficient for maintaining optimized lead levels. Includes tables, figures.