| Unit Pref: | Imperial |
| Settlement Type: | Township |
| Official Name: | South Ottawa Township |
| Image Map1: | Map of Illinois highlighting LaSalle County.svg |
| Mapsize1: | 150px |
| Map Caption1: | LaSalle County's location in Illinois |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | LaSalle |
| Leader Title: | Supervisor |
| Established Title: | Established |
| Established Date: | November 6, 1849 |
| Area Total Sq Mi: | 21.05 |
| Area Land Sq Mi: | 19.67 |
| Area Water Sq Mi: | 1.38 |
| Area Water Percent: | 6.56 |
| Population As Of: | 2010 |
| Population Density Sq Mi: | 421.4 |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Pop Est As Of: | 2016 |
| Pop Est Footnotes: | [1] |
| Population Est: | 8093 |
| Blank Name: | FIPS code |
| Blank Info: | 17-099-71110 |
South Ottawa Township is located in LaSalle County, Illinois. As of the 2010 census, its population was 8,290 and it contained 3,609 housing units.[2]
According to the 2010 census, the township has a total area of, of which (or 93.44%) is land and (or 6.56%) is water.[2]