When was Lake Sakakawea formed?

Lake Sakakawea, one of the largest man-made reservoirs in the United States, was formed as part of a monumental mid-20th century effort to control flooding, generate hydroelectric power, and manage water resources along the Missouri River. The lake was created by the construction of Garrison Dam, which began in the late 1940s and was completed in the 1950s. The process of filling the reservoir and forming Lake Sakakawea officially began in 1953 and was largely completed by 1956, though final adjustments and development continued into the early 1960s.

Background: The Pick-Sloan Plan

Lake Sakakawea’s origins are tied to the Pick-Sloan Missouri Basin Program, a comprehensive water development plan authorized by the U.S. Congress in 1944. This ambitious project was designed to address issues like flooding, drought, navigation, irrigation, and power generation along the Missouri River and its tributaries. One of the key components of this plan was the construction of a series of large dams, including Garrison Dam in North Dakota.

Construction of Garrison Dam

Construction on Garrison Dam, which would eventually create Lake Sakakawea, began in 1947 and was overseen by the U.S. Army Corps of Engineers. The dam was built across the Missouri River near Riverdale, North Dakota, and it quickly became one of the largest earth-fill dams in the world. The project employed thousands of workers and represented one of the largest civil engineering efforts in U.S. history at the time.

After years of construction, the dam was completed in 1953, and engineers began to impound the waters of the Missouri River to create the reservoir. It took several years for the lake to reach its intended full pool elevation of approximately 1,850 feet above sea level. By 1956, Lake Sakakawea had essentially reached its current size and shape.

Impact on Communities and the Environment

The formation of Lake Sakakawea brought significant changes to the region. The reservoir flooded over 550 square miles (about 1,420 square kilometers) of land, including large sections of Native American reservations such as the Fort Berthold Indian Reservation. Entire communities—including the towns of Sanish, Elbowoods, and Van Hook—were inundated, and thousands of residents were displaced. Much of the fertile Missouri River bottomland used for agriculture was permanently lost, and tribal nations were forced to relocate to less productive lands.

While the creation of the lake provided flood control and hydroelectric power benefits, it also caused lasting social, cultural, and economic disruptions, particularly for the Mandan, Hidatsa, and Arikara (Three Affiliated Tribes).

A New Era for North Dakota

By the late 1950s, Lake Sakakawea had become a defining feature of northwestern North Dakota. The reservoir brought opportunities for recreation, tourism, and water supply. The surrounding region saw the development of state parks, marinas, fishing areas, and campgrounds. Today, Lake Sakakawea continues to serve multiple purposes, including hydroelectric power generation at Garrison Dam, wildlife conservation, and outdoor recreation.

Conclusion

Lake Sakakawea was officially formed beginning in 1953, following the completion of Garrison Dam, and reached its full size by 1956. Born out of the ambitious Pick-Sloan Plan, the lake has had a profound and complex impact on the people and environment of the Missouri River Basin. While it stands as a testament to American engineering and resource management, it also serves as a reminder of the human and environmental costs associated with large-scale infrastructure projects.