Floods can be good for the flood plain, but they also can be damaging. Many towns are built along rivers, too. When a river floods, it can damage homes and businesses in these towns. People have built levees and dams to prevent floodwaters from reaching their towns. Levees are high banks built along rivers that keep them from overflowing.
Dams are structures built on rivers that control the flow of water.
The Mississippi and some of its tributaries use both levees and dams for flood control. Unfortunately, sometimes these do not work and damage occurs. Dams also have other uses. On some fast-moving rivers, dams generate electricity. Dams also store water in big lakes called reservoirs.