The South Grand River Watershed occupies a land area of approximately 2,046 square miles in portions of 8 counties in Missouri and 2 Counties in Kansas (Figure Lo01). These counties include Bates, Benton, Cass, Henry, Jackson, Johnson, Pettis, and St. Clair Counties in Missouri and Johnson and Miami in Kansas. Most of the watershed (98.5%) lies within Missouri (The portion of the watershed occurring in Kansas is not addressed in this document except where otherwise noted). The watershed is bounded to the West and Southwest by the Maries des Cygnes Watershed and to the South and East by the Upper Osage Watershed both of which have been combined as the West Osage Basin in the West Osage Basin Inventory and Management Plan (MDC 1997). The Lamine and Blackwater Watersheds border the South Grand on the northeast side while the Missouri River main stem Drainage borders the watershed to the north.
The South Grand River is formed by the confluence of Massey Creek and East Creek approximately 5 miles southwest of Peculiar, Missouri. From its beginnings, the river flows in a southeasterly direction for approximately 28 miles before turning to flow east for another 16 miles. It once again turns to a southeasterly direction and continues for another 9 miles before receiving the flow of Big Creek, the largest tributary to the South Grand. From this point, the South Grand continues in a general southeast direction for approximately 14 miles before emptying into Harry S. Truman Reservoir near Clinton, Missouri. Approximately 62 original miles of the South Grand River have been impounded by Truman Reservoir (MDNR 1986). Prior to impoundment, the South Grand emptied into the Osage River 2.25 miles northwest of Warsaw, Missouri. There are two fifth order streams in the watershed which were once tributaries to the South Grand River, however they now flow into Truman Reservoir. These are Deepwater Creek and Tebo Creek.
Truman Reservoir, the largest impoundment in the South Grand River Watershed, impounds approximately 55,600 surface acres of water at the top of the multipurpose pool (USACOE 2002). Approximately 42% of Truman Reservoir, which also receives inflow from the Osage, Sac, and Pomme de Terre Rivers, is within the South Grand River Watershed.
The South Grand River Watershed has 13 cities and towns with populations exceeding 1,000 persons within or partially within its boundary. These included Adrian, Belton, Clinton, Garden City, Greenwood, Harrisonville, Holden, Kansas City, Lee's Summit, Peculiar, Pleasant Hill, Raymor, and Windsor. All of these are within Missouri.
The South Grand River Watershed includes approximately 4,605 miles of road. This is 2.3 miles of road for every square mile of drainage area. Two U.S. Highways and 10 state numbered routes intersect the South Grand Watershed. (Figure Lo02). In addition, 176 miles of railroad intersect the watershed.