Folsom 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...

 gravity dam on the American River

American River

The American River is a California watercourse noted as the site of Sutter's Mill, northwest of Placerville, California, where gold was found in 1848, leading to the California Gold Rush...

 in Northern California

Northern California

Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...

, about 25 miles (40.2 km) northeast of Sacramento

Sacramento, California

Sacramento is the capital city of the U.S. state of California and the county seat of Sacramento County. It is located at the confluence of the Sacramento River and the American River in the northern portion of California's expansive Central Valley. With a population of 466,488 at the 2010 census,...

. Folsom Dam is 340 feet (103.6 m) high 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...

 and 1400 feet (426.7 m) long, flanked by earthen wing dams. It was completed in 1955, officially opening the following year.

The dam, at the juncture of the north and south forks of the American River, was built by the United States Army Corps of Engineers

United States Army Corps of Engineers

The United States Army Corps of Engineers is a federal agency and a major Army command made up of some 38,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency...

, and upon its completion, was transferred to the United States Bureau of Reclamation

United States Bureau of Reclamation

The United States Bureau of Reclamation , and formerly the United States Reclamation Service , is an agency under the U.S...

.