Watertown Township is a civil township of Tuscola County in the U.S. state of Michigan. The population was 2,231 at the 2000 census.
According to the United States Census Bureau, the township has a total area of 32.9 square miles (85.2 km²), of which, 32.7 square miles (84.6 km²) of it is land and 0.2 square miles (0.6 km²) of it (0.76%) is water.
As of the census of 2000, there were 2,231 people, 796 households, and 631 families residing in the township. The population density was 68.3 per square mile (26.4/km²). There were 874 housing units at an average density of 26.8 per square mile (10.3/km²). The racial makeup of the township was 98.43% White, 0.18% African American, 0.58% Native American, 0.04% Asian, 0.22% from other races, and 0.54% from two or more races. Hispanic or Latino of any race were 0.72% of the population.