Is the Twain Harte Community Services District (THCSD) the same thing as the Water District?   

Yes and no. THCSD is a California governmental entity formed to provide water, sewer, fire, park/recreation and hydroelectric services. THCSD assumed the water service in the community of Twain Harte upon its creation in 1996, when the Tuolumne County Water District #1 was dissolved.