The Lake of the Ozarks is a large reservoir created by impounding the Osage River in the northern part of the Ozarks in central Missouri. Extents of three smaller tributaries to the Osage, the Niangua River, Grandglaize Creek, and Gravois Creek, are included in the impoundment. The lake has a surface area of 55,000 acres (223 km²), over 1,150 miles (1,850 km) of shoreline, and the main channel of the Osage Arm stretches 92 miles (148 km) from end to end.