Oahe Dam on the Missouri River near Pierre, South Dakota, is built of more than 93 millions of tons of packed earth, rock, and concrete. But a dam has to do more than just hold back water.
Construction of the Oahe Dam on the Missouri River northwest of Pierre began in 1948 and took 10 years to complete. Final closure was accomplished on August 3, 1958.
The film above shows workers using heavy machinery to move earth and rock. The film also shows a portion of the 1958 closure, which was accomplished in one relatively rapid, continuous effort over the course of just hours.
It took almost four years for the water level in Lake Oahe to reach its "minimum operating pool," a volume of water large enough to allow power generation. President John F. Kennedy dedicated the dam on August 17, 1962, the date on which the power station went online.
When it was built, Oahe Dam was the second-largest rolled-earth dam in the world. It's reservoir created the 4th largest reservoir in the United States.
The film below, from the 1950s, shows the construction of the emergency tunnels used for floodwater release, the massive water intake tower upstream from the dam, and several other structures that really make Oahe work. Notable in the film are shots of the emergency gates tested for the first time in April 1957.
Fifty-four years later, during the Missouri River Flood of 2001, those tunnels and gates would be used for real. The video below shows the tunnels and other structures capable of moving 150,000 cubic feet per second (CFS) of river water.
OTHER MEDIA
Learn more about Oahe and the other dams on the Missouri River in this SDPB documentary, which focuses on the record-breaking Missouri River floods of 2011.
For Teachers: Activity idea is available at SDPB's Digital Learning Library.
Source: U.S. Army Corps of Engineers