[3] Watertown Township was organized in 1858, and named from the numerous bodies of water within its borders.

Township 117 North, Range 25 West, Fifth Principal Meridian of the Public Land Survey System.

The township contains the following cemeteries: Saint Paul's Catholic and Zion.

As of the census[1] of 2000, there were 1,432 people, 478 households, and 393 families residing in the township.

14.2% of all households were made up of individuals, and 4.4% had someone living alone who was 65 years of age or older.