The Hebgen Dam is a concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

-core earthen embankment dam

Embankment dam

An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...

 on the Madison River

Madison River

The Madison River is a headwater tributary of the Missouri River, approximately 183 miles long, in Wyoming and Montana. Its confluence with the Jefferson and Gallatin rivers near Three Forks, Montana form the Missouri River....

 in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

. The dam is 85 feet tall and 721 feet long. The dam is owned and operated by PPL Montana

PPL (utility)

PPL, formerly known as PP&L or Pennsylvania Power and Light, is an energy company headquartered in Allentown, Pennsylvania, USA. It currently controls about 19,000 megawatts of electrical generating capacity in the United States, primarily in Pennsylvania and Montana, and delivers electricity to...

 and its purpose is to store and regulate water for other downstream reservoirs and hydroelectric power plants.

The dam was built in 1914 and created Hebgen Lake

Hebgen Lake

Hebgen Lake is a lake located in Southwest Montana and is created by Hebgen Dam. It is well known for a magnitude 7.5 earthquake which occurred nearby on August 17, 1959, forming Quake Lake which is located immediately downstream.-Recreation:...

. After the 1959 Yellowstone earthquake

1959 Yellowstone earthquake

The 1959 Yellowstone earthquake also known as the Hebgen Lake earthquake was a powerful earthquake that occurred on August 17, 1959 at 11:37 pm in southwestern Montana. The earthquake was registered at magnitude 7.3 – 7.5 on the Richter scale...

, the dam was damaged but it was fixed several weeks later. On August 30, 2008, two of the dam's four hydraulic gates failed, releasing 3400 ft3 per second of water into the Madison River. The normal discharge of the dam is 900 ft3 per second and the gate failure caused a 1-foot rise in the river.