The Nodaway River is a 65.7-mile-long tributary that flows from southwest Iowa through northwest Missouri into the Missouri River. It is considered a major water source by the Iowa DNR. The river's name first appears in the journal of Lewis and Clark, who camped at the mouth of the river on July 8, 1804, but who provide no derivation of the name. The name is an Ot…The Nodaway River is a 65.7-mile-long tributary that flows from southwest Iowa through northwest Missouri into the Missouri River. It is considered a major water source by the Iowa DNR. The river's name first appears in the journal of Lewis and Clark, who camped at the mouth of the river on July 8, 1804, but who provide no derivation of the name. The name is an Otoe-Missouria term meaning "jump over water". The term would be spelled today in full as Nyi At'ąwe and would be contracted in regular speech as Nyat'ąwe or Nat'ąwe.