Ottumwa, IA -- U.S. city in Iowa Population (2000): 24998 Housing Units (2000): 11038 Land area (2000): 15.799483 sq. miles (40.920471 sq. km) Water area (2000): 0.673981 sq. miles (1.745603 sq. km) Total area (2000): 16.473464 sq. miles (42.666074 sq. km) FIPS code: 60465 Located within: Iowa (IA), FIPS 19 Location: 41.012917 N, 92.414817 W ZIP Codes (1990): Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Ottumwa, IA Ottumwa