The City of Milwaukee recently began to operate new ozone facilities for inactivation of Cryptosporidium oocysts at its two water treatment facilities. The basic operating criterion for ozonation was to meet a target CT for 2-log Cryptosporidium inactivation based on a multiplier of five times the CT values for 2-log Giardia inactivation. The CT value was calculated on-line using an integrated CT method. By following this approach, the operations staff minimized the ozone dosage required to meet the disinfection goals. Along with inactivation of Cryptosporidium, ozone addition was expected to have other beneficial effects on plant operations, finished water quality, costs, and customer satisfaction. The City set up a tracking and review system that included these factors.