People build dams to control water—to make sure the right amount is at the right place at the right time.
River water rises behind dams, forming artificial lakes called reservoirs. The stored water can be used to generate electricity or to supply water for homes and industries, for irrigation or for navigation. Reservoirs also are good places to fish, swim and play.
Engineers use models and computers to figure out how much water a dam will have to support and how big and strong it must be. Then they can decide what sort of dam to design.
There are four main types of dams:
If a dam is well designed, it will be strong enough to hold back the water behind it, whatever happens. But tragic accidents still occur, often caused by the unimaginable power of natural forces such as earthquakes, landslides or floods.
The worst dam disaster happened over a century ago. A huge dam in Johnstown, Penn., burst in 1889, killing more than 2,200 people.
More recently, in 1976, the Teton Dam in Idaho broke as the reservoir behind it was being filled for the first time. Eleven people were killed. The Teton Dam disaster resulted in new government rules to ensure that dams are safe.
Every TVA dam is checked regularly to make sure it that it is safe and the equipment used to operate it is working properly. Read more about dam safety at TVA.
Because many of these dams were built in the 1930s, TVA has had to do a lot of work on them to make sure that they meet modern safety regulations. These ensure that TVA’s dams can stand up to the biggest flood or earthquake that we would ever expect to see in the Tennessee Valley.