With virtually no local water sources available for use, the City of San Diego relies on water from the Metropolitan Water District, which imports its water from the Colorado River and the California State Water Project. The two massive water projects bring water from other watersheds and regions hundreds of miles to the north and east. Constructed as a conventional treatment plant, the Otay Water Treatment Plant used chlorine dioxide produced from chlorine gas for disinfection as the incoming water was high in naturally occurring organic matter. While the use of chlorine gas provided a strong disinfectant for the treated water, operators with the City began to consider other disinfection options as the area surrounding Otay grew and expanded. Read the full case study to learn more.