 For the last seventy years, Lake Travis (Mansfield Dam) and Lake Buchanan (Buchanan Dam), have provided water, hydroelectric power, and flood control for Central Texas.Between 1880 and 1920 Austin's population grew threefold to 34,876, but the city slipped from fourth largest in the state to tenth largest.The state's surging industrial development, propelled by the booming oil business, passed Austin by.