The new disinfection monitoring requirements of the Surface Water Treatment Rule include CT (contact time of disinfectants) compliance calculations, which can be confusing and time consuming. The Contra Cost Water District developed a spreadsheet that performs CT calculations quickly and easily. Operators can enter input variables in a few seconds, and the spreadsheet immediately calculates the CT compliance status of the plant. In addition to compliance monitoring, the spreadsheet can be used to predict what disinfectant residuals are required, or what the most suitable chemical application points are, under various operating conditions. Taking the idea a step further, a custom computer program was developed and installed in CCWD's Supervisory Control and Data Acquisition system to provide real-time online readings of the CT compliance status. The program is based on the spreadsheet software. The program periodically polls the Bollman Water Treatment Plant remote terminal unit, which updates the host computer's database with the current plant operating conditions for CT calculations. Disinfection is accomplished with monochloramines.