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Lewis and Clark: Big Dam Era

Historically, the Missouri River's flood pulse resulted from rain and melting snow runoff that would start in March in the upper Great Plains.

During some years, spring floods inundated city streets and buildings, made homes uninhabitable and ruined newly planted crops. The Missouri had always flooded. During Marquette's explorations, he experienced one of the river's great floods and wrote, "I have seen nothing more frightful."

Even a single rise of the river would erode banks as much as 300 feet. Its constantly changing channels relocated more than 2,000 feet in some places and deposited huge amounts of silt in other places.

Cover of LIFE Magazine, featuring Fort Peck Dam, November 23, 1936    
The construction of Fort Peck Dam
was the cover story of the first issue
of LIFE Magazine, November 23, 1936

This erosion and siltation hampered navigation and the permanency of bottomland farms and river towns. President Franklin D. Roosevelt visited South Dakota in 1932 during the worst days of the Dust Bowl as the pasture and crops choked in the barren desert that once was lush green land. The President pointed to the Missouri River and said, "This is the greatest resource of your state. It's got to be developed."

In April 1943, a sudden spring thaw unleashed the mean side of the normally calm river. Six lives were lost and 70,000 acres of farmland were flooded. Downtown Omaha, Nebraska, was inundated and the runways of Omaha's airports were under eight feet of water. In May heavy rains caused further flooding in the lower end of the basin. An additional half million acres of farmland were flooded. And again in June the heavens opened. Some areas received seven inches of rain per day. Nearly a million more acres of farmland were flooded. When totaled, flood damages in 1943 exceeded $100 million and brought a cry to Congress for flood control relief along the river.

Instead of each promoting rival programs, Congress asked the agencies to compromise and develop one plan that complemented both of them. The Missouri River Basin Project, was born in 1944, and, in honor of its founders, it was renamed the Pick-Sloan Missouri Basin Program in 1970.

The Pick-Sloan Program is one of the most comprehensive plans ever developed for management of an entire region's water resources. The Corps was responsible for navigation and flood control, while the Bureau's role was development of irrigation and other uses. The already completed Fort Peck Dam was integrated into the program and the Corps was charged with building five additional dams on the Missouri River.

The Missouri River reservoir system is the largest in the United States with a storage capacity of 74 million-acre feet and a surface area exceeding one million acres. The six dams built in Montana, Nebraska, North Dakota and South Dakota transformed one-third of the Missouri River ecosystem into lake environments.

The six mainstem dams from north to south along the Missouri River are:

Fort Peck Dam:

The first of the Missouri River mainstem dams to be constructed, Fort Peck, in northeastern Montana, had been promoted as a good location for a dam as far back as 1877. An ice gorge that year caused a backup of water a mile up the river, flooding the booming trading post called Fort Peck that also was headquarters for the Milk River Indian Agency. The fort's owner, Colonel Campbell Kennedy Peck, was a friend of President Chester Arthur and is believed to have gone to Washington, D.C., in 1879 to plead for a dam to serve navigation and irrigate reservation lands.

Some 50 years later Fort Peck area business leaders and politicians were still pushing for a dam. The country's water resource development plans were taking shape, with irrigation and flood control being incorporated into legislation from the early 1900s on. After extensive study of the Missouri River, Captain Wyman, a Corps of Engineers District Engineer, prepared an extensive report that advocated the development of flood control, irrigation and hydroelectric projects. He considered building a navigation reservoir at Fort Peck to be the first step in making these plans a reality.

President Franklin Roosevelt approved construction of the Fort Peck Dam in October 1933. In addition to being the first project in the Missouri River water development plan, this project also brought Depression-era employment and training to tens of thousands of people. The common laborers could make what was considered a very decent wage of 50 cents an hour. The number of on-site workers peaked at 10,546 in 1936 and totaled more than 7,000 in several other years. The dam was completed in the fall of 1940.

Garrison Dam:

Plans for the second of the Missouri River mainstem dams were to locate it 75 miles north of Bismarck. It was designed to be the largest of dam of its type ever constructed at 12,000 feet long, 210 feet high, and impounding a 200-mile long reservoir that could contain 23 million acre-feet of water. This was a volume almost 20 percent greater than that impounded by Fort Peck Dam. The project was approved in August 1945. The following year construction began on the town of Riverdale, which was located a mile and a half from the damsite. When it was completed in 1950, Riverdale housed 4,000 residents. The work on the dam's embankment alone took seven years to complete, with as much as 80,000 cubic yards of earth being moved every day. President Dwight Eisenhower came to North Dakota to dedicate the dam in June 1953.

Oahe Dam:

Further south in central South Dakota is Oahe Dam. It is the third of the mainstem dams and the fourth-largest man-made reservoir in the country, with a storage capacity of 23.5 million acre-feet. Its construction began in 1948 and it began generating hydroelectric power in 1962. The capitals of the Dakotas, Bismarck and Pierre, are at the north and south tips of Lake Oahe, the 231-mile reservoir the dam creates. President John F. Kennedy officially dedicated the dam and the lake in August 1962.

Big Bend Dam:

A unique bend in the Missouri River in south central South Dakota brings the river to a near complete loop, traveling 25 miles before returning to the neck, where the land is only about a mile wide. Construction began on the Big Bend Dam in 1959 and its embankment was closed in July 1963. Its first generating unit went into operation in 1964 and by 1966 all eight generators were producing electricity. Its generation capacity is 493,000 kilowatts, and its reservoir, Lake Sharpe, has a shoreline of 200 miles.

Fort Randall Dam:

Like Fort Peck and Garrison Dams, Fort Randall Dam required a new town to house the people who would build and maintain it. From 1946 to 1950, the Omaha District of the Corps of Engineers built Pickstown, South Dakota, just north of the Nebraska state line. Pickstown would house 3,500 workers, and at the height of its construction, almost 5,000 peopled work on the dam. Its first power flowed in March 1954, with President Eisenhower speaking over the radio from the White House to 600 people gathered at the Dam's powerhouse. The dam has a generation capacity of 320,000 kilowatts. Its reservoir, Lake Francis Case, has a shoreline of 150 miles.

Gavins Point Dam:

Just north of the Nebraska state line, Gavins Point Dam was completed in 1957 and has a generation capacity of 44,099 kilowatts. Its reservoir, Lewis and Clark Lake, has a shoreline length of 90 miles. Construction of the dam began in 1952 at a cost of $51 million. It is the smallest of the six Upper Missouri River Basin mainstem dams, but it plays a key role in the successful operation of the Pick-Sloan Plan. Water released from the five upstream dams is stored at Lewis and Clark Lake for production of hydroelectric power. The dam controls uniform flows on the open river to St. Louis, enhancing navigation opportunities and minimizing bank erosion.

Last Updated: March 6, 2013

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