Ottumwa (/əˈtʌmwə/; ə-TUM-wə) is a city in and the county seat of Wapello County, Iowa, United States. The population was 25,529 at the time of the 2020 U.S. Census. Located in the state's southeastern section, the city is split into northern and southern halves by the Des Moines River. Ottumwa serves as a major economic, commercial, and cultural hub for the Southeastern Iowa region.