Watertown is located at 44°53'57" North, 97°6'52" West (44.899444, -97.114722).
According to the United States Census Bureau, the city has a total area of 23.09 mi2 (59.81 km2). 15.23 mi2 (39.44 km2) of it is land and 7.86 mi2 (20.37 km2) of it is covered by water. The total area is 34.05% water.
Watertown is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).