Optimized nitrification control strategies are key to Louisville Water’s successful management of disinfectant residual and maintenance of distribution water quality. The approach Louisville Water uses to execute an overall water-quality management program may differ from other utilities depending on the objectives, as programs should vary based on the unique characteristics of distribution systems including size, customer demands, effects of individual utility treatment, and distribution infrastructure maintenance strategies. The Louisville Water distribution system includes over 4,200 miles of main and over 30 finished-water storage facilities (ranging in size from 0.1 MG to 30 MG). Maintaining disinfectant residual has been one of Louisville Water’s most challenging distribution water-quality management activities in recent years, primarily due to increasing water age and subsequent nitrification events. The increase in water age is a result, in part, of declining average residential demands, ex-urban expansion of the distribution system away from the core infrastructure, and relatively dry, hot summer periods, which have not necessarily translated into high peak-demand periods. Successfully managing consistent disinfectant residual and maintaining the overall quality of water throughout our system has required Louisville Water to optimize nitrification control strategies. Through a culture of continuous improvement, Louisville Water has combined common historical practices with new methods and technology to manage disinfectant residual strategically and efficiently. This presentation highlights improvements and results including optimized treatment, remote monitoring of disinfectant residual, field water-quality data collection and analysis, enhanced flushing approaches, distribution treatment, active and passive mixing, optimized pumping and operational strategies, and continuing research. These optimizations and enhancements have leveraged resources and technologies in both capital and O&M activities. Louisville Water continues to develop and integrate best industry practices into nitrification control and all other areas of distribution-system water-quality management. Louisville Water employs adaptive management practices to stay ahead of emerging regulations and to optimize the effectiveness of its resources to meet current and future challenges. These practices can be implemented by other utilities looking to optimize distribution water-quality management programs.