How Many Dams Are on the Missouri River?

The Missouri River, often dubbed the “Big Muddy,” is impounded by six major dams, all operated by the U.S. Army Corps of Engineers (USACE), forming the Missouri River Mainstem Reservoir System. These dams, crucial for flood control, navigation, irrigation, and power generation, dramatically altered the river’s natural flow and ecosystem.

The Big Six: A Closer Look at Missouri River Dams

While smaller structures and diversions exist along the Missouri and its tributaries, the six major dams on the mainstem are the defining feature of the river’s management. These massive projects, constructed in the mid-20th century, represent a significant engineering achievement and a profound intervention in the natural landscape. Let’s explore each one in detail:

Fort Peck Dam: Located in northeastern Montana, Fort Peck is the largest of the six dams. It impounds Fort Peck Lake, a vast reservoir that provides significant flood control and recreational opportunities.
Garrison Dam: Situated on the Missouri River in central North Dakota, Garrison Dam creates Lake Sakakawea, the third-largest artificial reservoir in the United States. This dam plays a crucial role in regulating downstream flows and generating hydropower.
Oahe Dam: Located near Pierre, South Dakota, Oahe Dam forms Lake Oahe, another large reservoir that extends into North and South Dakota. The dam is important for flood control, irrigation, and power generation.
Big Bend Dam (Lake Sharpe): Situated in central South Dakota, Big Bend Dam creates Lake Sharpe. While smaller than the other reservoirs, Lake Sharpe contributes to the overall regulation of the Missouri River’s flow.
Fort Randall Dam: Located in south-central South Dakota, Fort Randall Dam impounds Lake Francis Case. This dam is a key component of the Missouri River’s flood control system and also generates electricity.
Gavins Point Dam: The southernmost of the six mainstem dams, Gavins Point Dam is located on the Missouri River near Yankton, South Dakota. It forms Lewis and Clark Lake and is crucial for maintaining navigation flows downstream.

These six dams, collectively, have transformed the Missouri River from a free-flowing, dynamic waterway into a regulated system of reservoirs and channels. This transformation has had both positive and negative consequences, impacting everything from flood control and water supply to fish and wildlife populations and sediment transport.

The Impact of Dams: Benefits and Challenges

The construction of the Missouri River dams brought significant benefits, including:

Flood Control: The reservoirs created by the dams provide storage capacity to absorb floodwaters, reducing the risk of devastating floods downstream.
Navigation: Regulated flows from the dams help maintain a navigable channel for barge traffic, supporting commerce and transportation.
Irrigation: Water stored in the reservoirs is used for irrigation, supporting agriculture in the surrounding region.
Hydropower: The dams generate electricity, providing a clean and renewable energy source.
Recreation: The reservoirs offer opportunities for boating, fishing, swimming, and other recreational activities.

However, the dams have also had significant negative impacts:

Habitat Loss: The inundation of vast areas of land behind the dams destroyed valuable habitat for fish and wildlife.
Altered River Flows: The dams have drastically altered the natural flow regime of the Missouri River, impacting fish spawning, sediment transport, and other ecological processes.
Sedimentation: The dams trap sediment, reducing its flow downstream and impacting the health of the river ecosystem.
Impacts on Fish Populations: The dams have fragmented fish populations and hindered their ability to migrate upstream to spawn.
Water Quality: Changes in water temperature and oxygen levels in the reservoirs can impact water quality and harm aquatic life.

Understanding both the benefits and challenges associated with the Missouri River dams is crucial for making informed decisions about the river’s management. Balancing the needs of various stakeholders, including agriculture, navigation, recreation, and environmental conservation, requires a comprehensive and adaptive approach.

Frequently Asked Questions (FAQs) About Missouri River Dams

Here are some commonly asked questions about the dams on the Missouri River, providing further insight into their purpose, operation, and impact.

FAQ 1: Who is responsible for managing the Missouri River dams?

The U.S. Army Corps of Engineers (USACE) is responsible for managing and operating the six mainstem dams on the Missouri River. The USACE works in coordination with other federal and state agencies, as well as tribal governments and stakeholders, to manage the river for multiple purposes.

FAQ 2: What is the Missouri River Mainstem Reservoir System?

The Missouri River Mainstem Reservoir System refers to the six reservoirs created by the major dams on the Missouri River: Fort Peck Lake, Lake Sakakawea, Lake Oahe, Lake Sharpe, Lake Francis Case, and Lewis and Clark Lake. These reservoirs are managed as an integrated system to achieve multiple objectives.

FAQ 3: What is the Master Manual and how does it govern dam operations?

The Master Manual is a comprehensive document that guides the operation of the Missouri River Mainstem Reservoir System. It outlines the rules and procedures for managing water releases from the dams to meet various objectives, including flood control, navigation, irrigation, power generation, and fish and wildlife conservation.

FAQ 4: How do the dams affect the Missouri River’s flow regime?

The dams significantly alter the Missouri River’s flow regime by reducing peak flows during floods and increasing flows during low-flow periods. This flow regulation helps to reduce the risk of flooding and maintain a navigable channel, but it also disrupts natural ecological processes.

FAQ 5: What are the implications of sediment trapping behind the dams?

The dams trap a significant amount of sediment that would normally flow downstream. This sediment trapping can lead to erosion of the riverbed downstream of the dams, reduced habitat for fish and wildlife, and decreased fertility of agricultural lands.

FAQ 6: How do the dams impact fish populations in the Missouri River?

The dams have fragmented fish populations and hindered their ability to migrate upstream to spawn. The physical barriers created by the dams, as well as altered flow regimes and water quality, have contributed to declines in populations of native fish species.

FAQ 7: What are the ongoing efforts to mitigate the environmental impacts of the dams?

The USACE and other agencies are implementing various measures to mitigate the environmental impacts of the dams, including:

Habitat restoration projects: Restoring wetlands and other habitats along the river to benefit fish and wildlife.
Flow management strategies: Modifying dam operations to mimic natural flow patterns and improve habitat conditions.
Fish passage structures: Constructing fish ladders or other structures to allow fish to bypass the dams and migrate upstream.
Sediment management strategies: Exploring ways to release sediment from the reservoirs to restore natural sediment transport processes.

FAQ 8: What is the Pick-Sloan Missouri Basin Program?

The Pick-Sloan Missouri Basin Program was a large-scale water development project authorized by Congress in 1944. It included the construction of the six mainstem dams on the Missouri River, as well as numerous other water projects throughout the basin. The program was designed to provide flood control, irrigation, power generation, and other benefits to the region.

FAQ 9: How has the management of the Missouri River dams evolved over time?

The management of the Missouri River dams has evolved significantly over time in response to changing priorities and scientific understanding. Early management focused primarily on flood control and navigation, but more recently, there has been increased emphasis on environmental conservation and restoring the river’s ecological health.

FAQ 10: What role do tribal governments play in managing the Missouri River?

Tribal governments have a significant stake in the management of the Missouri River, as many tribes have treaty rights and cultural connections to the river. The USACE consults with tribal governments on dam operations and other management decisions that could affect tribal resources and interests.

FAQ 11: How is climate change affecting the Missouri River and its management?

Climate change is expected to have significant impacts on the Missouri River, including changes in precipitation patterns, increased temperatures, and more frequent and intense droughts and floods. These changes will pose new challenges for managing the river and its dams, requiring adaptive management strategies to ensure sustainable water supplies and ecosystem health.

FAQ 12: Where can I find more information about the Missouri River dams?

You can find more information about the Missouri River dams from the following sources:

U.S. Army Corps of Engineers (USACE) website: The USACE website provides information about dam operations, water management, and environmental studies.
U.S. Geological Survey (USGS) website: The USGS website provides data on river flows, water quality, and other hydrologic parameters.
State agency websites: State agencies in the Missouri River Basin provide information about water management, fish and wildlife, and recreation.
Academic research: Numerous research papers and reports have been published on the Missouri River and its dams.

By understanding the history, operation, and impacts of the Missouri River dams, we can work towards a more sustainable and balanced approach to managing this vital resource for future generations. The future of the Missouri River depends on thoughtful planning and collaboration among all stakeholders.