Lake of the Ozarks is a large central Missouri reservoir created when Bagnell Dam blocked the Osage River in 1929–1931, with waters extending into several tributaries and forming about 1,150 miles of shoreline. Built for hydroelectric power by Union Electric with Stone and Webster as principal engineers, it was considered the largest man-made lake in the United States at the time. An earlier private development effort had failed before construction began. The lake soon became a major tourist destination because of its stable water level, extensive recreation, and resort growth, while still serving as a working hydroelectric reservoir under federally regulated management.