The river basin which drains approximately 508 square miles (1,316 km2)[3] is sandwiched between the Nishnabotna River to the west and the Nodaway River to the east.
The name "Tarkio" is from a Native American word meaning "place where walnuts grow".[4][5]
The river passes rural areas and figures most prominently in the drainage system nears its mouth in management of Big Lake, Missouri and the Loess Bluffs National Wildlife Refuge, formerly known as Squaw Creek National Wildlife Refuge. Several streams and ditches in the Missouri River bottoms near its mouth contain the Tarkio name.
There are several streams with the Tarkio name in the Missouri River bottoms near where the Tarkio meets the Missouri. Almost none of the streams actually flows into the Tarkio although some are historically part of the river.
Old Channel Tarkio River - The river originally flowed further south along the base of the bluffs by Craig, Missouri. It now drains into Little Tarkio Creek.
Little Tarkio Creek - The creek which begins in the bluffs above the Missouri flows on the east side of Big Lake and passes Fortescue, Missouri before emptying into the Missouri at RM 493 (RK 793).
Old Channel Little Tarkio Creek - The creek flows on the west side of Squaw Creek National Wildlife Refuge and drains into Little Tarkio Ditch
Little Tarkio Ditch - The ditch drains the water from the Squaw Creek National Wildlife Refuge and drains into the Missouri at approximately RM 485 (RK 781).
Flooding
The drainage of the river through the flatlands of the Missouri can sometimes lead to spectacular floods when the river cannot drain. In the Great Flood of 1993 flooding caused Interstate 29 to be closed near the mouth. In the 2011 Missouri River floods, the Tarkio River and its other namesakes overwashed an area from Fortescue to the Missouri River totally obliterating Big Lake. On July 7, 2011 the river rose 8 feet (2.4 m) in six hours in one burst at Fairfax.[8]
