Map of the Osage River watershed showing the Sac River
|- location||Greene County, Missouri|
|- elevation||1,240 ft (380 m)|
|709 ft (216 m)|
|Length||118 mi (190 km)|
|Basin size||1,981 sq mi (5,130 km2)|
|- location||USGS 06919900 near Caplinger Mills, MO|
|- average||1,670 cu ft/s (47 m3/s)|
|- minimum||34 cu ft/s (0.96 m3/s)|
|- maximum||51,200 cu ft/s (1,450 m3/s)|
|- right||Little Sac River|
The Sac River is a river in the Ozarks of Southwest Missouri. It is 118 miles (190 km) long, with headwaters in western Greene County. The stream passes through the northeast corner of Lawrence County then re-enters Greene County. The stream enters Dade County northwest of Ash Grove. The stream enters Stockton Lake in Dade County between Dadeville and Greenfield, then flows north exiting Stockton Lake in Cedar County. The stream meanders north into St. Clair County, passes under US Route 54 and enters the Osage River in Truman Reservoir southeast of Osceola.
The river was named after the Sac Indians. The Big Eddy Site, an archaeological dig, is along the Sac River within Cedar County. Eleven feet of river sediment at the site provides a stratigraphy that suggests more than 10,000 years of nearly constant occupation by American Indians, potentially pre-dating the Clovis culture and contributing to the knowledge of the Dalton and San Patrice cultures.
- "Sac River". Geographic Names Information System. United States Geological Survey. Retrieved 2015-12-03.
- "Water-Data Report 2013 - 06919900 Sac River near Caplinger Mills, MO" (PDF). U.S. Geological Survey. Retrieved 2015-12-03.
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed May 31, 2011
- Missouri Atlas & Gazetteer, DeLorme, 1998, First edition, p. 43 and 51-52, ISBN 0-89933-224-2
- "Dade County Place Names, 1928–1945 (archived)". The State Historical Society of Missouri. Archived from the original on 24 June 2016. Retrieved 25 September 2016.