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NASHVILLE, Tenn. - When heavy rain falls across Tennessee and Kentucky, many people wonder: What is the U.S. Army Corps of Engineers doing to manage the water? The answer is a complex, coordinated effort involving monitoring, real-time decision-making, and strategic dam operations designed to reduce flood risks along the Cumberland River system.
While flood control is one of the Corps’ primary missions, the reality is that nature does not always cooperate. The USACE Nashville District’s highly trained engineers, dam operators, and other water management professionals carefully balance the flow of water through the system—holding back water when possible and releasing it in a controlled manner to minimize damage downstream.
The Scale of the Cumberland River System
The Cumberland River is an expansive waterway stretching 688 miles from its headwaters in Eastern Kentucky, flowing through Tennessee, and ultimately joining the Ohio River near Smithland, in Western Kentucky. The Cumberland River Basin, which includes the river and its network of tributaries, covers more than 18,000 square miles across Tennessee and Kentucky. This system plays a crucial role in flood risk management, navigation, hydropower, water supply, and recreation.
The Nashville District manages 10 dams on the Cumberland River and its tributaries, each serving unique purposes. However, not all of these dams have flood control capabilities. Some were built primarily for hydropower, navigation, or recreation, while others were designed to reduce flood risks by temporarily storing excess water during heavy rainfall events.
Dams and Their Role in Flood Control
Among the 10 dams in the Cumberland River system, six are designated as flood control reservoirs:
• Wolf Creek Dam (Lake Cumberland, KY)
• Dale Hollow Dam (Dale Hollow Lake, TN/KY)
• Center Hill Dam (Center Hill Lake, TN)
• J. Percy Priest Dam (J. Percy Priest Lake, TN)
• Martins Fork Dam (Martins Fork Lake, KY)
• Barkley Dam (Lake Barkley, TN/KY)
These flood control reservoirs function like massive holding tanks, capable of storing over a trillion gallons of water during heavy rain events. Without them, rainfall runoff would immediately flow into the Cumberland River, causing rapid and severe flooding in cities like Nashville, Clarksville, and communities all along the river.
To illustrate the impact of flood control storage, during the May 2010 Nashville flood, these reservoirs prevented an estimated $430 million in damages by reducing peak water levels and delaying floodwaters from overwhelming downstream communities.
Hydropower and Water Movement
In addition to flood control, nine of the Corps’ dams in the Cumberland River Basin generate hydropower, supplying electricity to hundreds of thousands of homes and businesses while also influencing water management decisions.
The nine USACE-operated hydropower dams in the Cumberland River system include:
• Wolf Creek Dam
• Dale Hollow Dam
• Center Hill Dam
• J. Percy Priest Dam
• Cordell Hull Dam
• Old Hickory Dam
• Barkley Dam
• Laurel Dam
• Cheatham Dam
Hydropower operations directly affect water movement because generating electricity requires releasing water through the dam's turbines. This means that when energy demand is high, power generation may need to increase, leading to additional water releases.
However, during major rainfall events, the Corps carefully weighs flood control needs against hydropower production. In extreme cases, power generation may be scaled back or halted to prioritize water storage and reduce flood risk.
On the other hand, in situations where floodwaters need to be moved downstream to prevent dam spillover or free up reservoir space, hydropower generation may be ramped up, using the turbines to pass water more gradually instead of releasing it all at once through spillway gates.
Balancing Multiple Priorities
The Cumberland River system is carefully managed year-round to ensure that flood control, navigation, hydropower, recreation, and water supply needs are met.
At any given time, USACE’s Water Management team analyzes multiple factors to determine the best course of action, including:
• Rainfall forecasts and river conditions
• Reservoir storage capacity and flood risk levels
• Energy demand and hydropower production schedules
• Navigation needs for commercial barge traffic
• Environmental and water quality considerations
This multi-purpose water management strategy ensures that the system remains resilient and responsive to changing conditions.
Coordinated Decision-Making with Key Partners
Flood management does not happen in isolation. The Nashville District works closely with a long list of partners during high-water events, including:
• The National Weather Service and Ohio River Forecast Center – Providing real-time forecasts of rainfall and river stages.
• Tennessee Emergency Management Agency and County Emergency Managers – Coordinating local flood response and safety efforts.
• Tennessee Valley Authority and other USACE Districts – Ensuring that dam releases in the Tennessee and Cumberland River systems do not create unintended downstream consequences.
• The Navigation Industry – Working with barge operators and commercial river traffic to manage safety during high flows.
• Higher USACE leadership, congressional leaders, the media and the public – communicating decisions and impacts.
Because the Cumberland and Tennessee Rivers flow into the Ohio River near one another, careful coordination is required to prevent unintended flooding along the Ohio and Mississippi Rivers downstream. This level of planning requires expertise, historical data, and real-time monitoring of conditions across multiple states.
What Happens During Heavy Rain? A Step-by-Step Look at Flood Operations
When heavy rain is forecast, USACE does not just react—it prepares. Managing flood risk in the Cumberland River Basin requires a careful balance of holding water back in reservoirs and making controlled releases to prevent major flooding downstream. The process begins well before the first raindrop falls and continues long after the storm has passed.
Before the Storm: Proactive Monitoring and Preparation
The USACE Water Management team monitors river and weather conditions year-round. The team works closely with the National Weather Service and the Ohio River Forecast Center to track incoming storms, rainfall projections, and potential flood impacts.
At this stage, the Corps assesses whether extra storage capacity is needed in flood control reservoirs. If conditions allow, dam releases may be gradually increased before the storm to lower reservoir levels, creating more space for incoming runoff. This is why communities may notice higher river levels before heavy rain events.
USACE also coordinates with emergency management agencies, Tennessee Valley Authority, and other stakeholders to ensure that all partners are prepared for potential high water. This includes briefing navigation industry stakeholders, as high river flows can impact commercial and recreational vessel traffic.
However, not all storms require the same response. The Water Management team operates at four levels to respond to changing weather and river conditions:
• Level 4 (Normal Conditions): Standard daily operations with routine monitoring of weather and river conditions. No significant weather threats.
• Level 3 (Watch): Increased monitoring due to heavy rain forecasts or rising river stages. Extra staff is on standby, and coordination with emergency agencies begins.
• Level 2 (Extended Hours): Operations extend beyond normal hours when rain exceeds four inches or rivers reach critical levels. More staff is on hand, and closer coordination with emergency teams occurs.
• Level 1 (24/7 Operations): Activated in extreme conditions, such as when rainfall exceeds six inches, flood control storage is maxed out, or dam safety threats arise. The Nashville District Water Management team operates around the clock, coordinating with emergency agencies and issuing frequent public updates.
During the Storm: Real-Time Water Management
As rain begins to fall, USACE shifts from preparation to active flood management. The Water Management team continuously monitors river gauges, rainfall totals, and inflow rates into reservoirs to determine the best course of action. Adjustments are made in real time to balance flood control, hydropower generation, navigation, and water supply needs, all while prioritizing public safety.
If conditions escalate, the Corps moves into Level 1 to ensure a continuous response to the evolving situation.
Water management decisions vary depending on the type of reservoir:
• Flood Control Reservoirs – Dams with flood storage capacity, such as Wolf Creek, Dale Hollow, Center Hill, J. Percy Priest, Martins Fork, and Barkley, hold back excess water to reduce downstream flooding.
• Run-of-the-River Projects and Hydropower Dams – While dams like Old Hickory, Cheatham, Cordell Hull, and Laurel do not have dedicated flood storage capacity, USACE may still lower their water levels ahead of major rainfall events. While these reservoirs cannot hold back water for long periods, adjusting levels in advance provides a buffer to help prevent overtopping and allows for more controlled releases.
One of the most critical flood management strategies is storing water in flood control reservoirs until downstream river levels recede. By temporarily holding back inflows, these reservoirs help prevent flooding in cities like Nashville, Clarksville, and other communities along the Cumberland River.
The amount of water held back depends on the severity of the rainfall event, the available storage in each reservoir, and downstream conditions. Even when a flood control reservoir reaches its maximum flood storage, water is still released in a controlled manner to prevent more significant flooding downstream.
One of the biggest misconceptions is that USACE can stop all flooding by holding water in reservoirs. While the Corps does maximize flood storage whenever possible, reservoirs can only hold so much water before releases are required to prevent overtopping or dam safety issues.
Additionally, many streams and tributaries in the Cumberland River Basin are unregulated, meaning they do not have dams to control water flow. When extreme rainfall hits these areas, flooding can still occur, and USACE’s ability to manage it is limited.
Again, looking back at the May 2010 Nashville Flood, the system was operated properly to reduce as much flooding as possible, but because of location and intensity of the rainfall, extensive flooding still occurred. While that was considered a greater than 1,000-year event, if that same 17-20 inches of rainfall over a two-day period were to occur again today, the region would see similar flooding.
While USACE manages water flows, the public also plays a critical role in flood safety. Residents in flood-prone areas should:
• Pay attention to flood warnings from local emergency officials.
• Avoid flooded roads—just two feet of water can sweep away a vehicle.
• Know your flood risk and take precautions if you live in a low-lying area.
• Stay away from dam spillways and flood gates where fast-moving water is extremely dangerous.
After the Storm: Recovery and Long-Term Planning
Once the rainfall subsides and river levels begin to recede, the work of flood management is far from over. The U.S. Army Corps of Engineers enters the post-storm phase, shifting its focus from immediate flood risk reduction to controlled water releases, system recovery, and long-term improvements.
The Water Management team carefully monitors river levels and works with the National Weather Service, TVA, and downstream USACE districts to determine the best timing and rate for releases. The goal is to restore reservoirs to normal pool levels while avoiding a second round of high water impacts downstream.
This process can take days or even weeks, depending on the volume of water stored and ongoing weather conditions. If additional rain is in the forecast, releases may be delayed or adjusted to ensure reservoirs have enough capacity to absorb future runoff.
Every high-water event presents unique challenges, and USACE conducts detailed after-action reviews to assess what worked well and where improvements can be made. These reviews involve engineers, dam operators, hydrologists, emergency managers, and leadership, as well as coordination with local, state, and federal partners.
Key topics of review often include:
• Effectiveness of dam operations and water management strategies
• Timeliness and accuracy of flood forecasts and communications
• Coordination between USACE, TVA, emergency agencies, and local governments
• Impacts on navigation, recreation, and hydropower generation
Lessons learned from these reviews help refine future flood response efforts, improve coordination, and enhance public communication strategies.
For some communities, a major flood event results in long-term challenges, including damaged infrastructure, economic losses, and continued flood risks. In some cases, these conditions lead to emergency declarations at the state or federal level.
When this happens, USACE may be called upon to support disaster response and flood mitigation efforts through:
• Post-Flood Studies: Identifying problem areas and developing potential solutions to reduce future flood risks.
• Flood Risk Reduction Projects: Constructing new levees, dams, or floodwalls to protect hard-hit communities.
• Technical Assistance: Providing engineering expertise to local and state governments to improve their flood resilience strategies.
• Emergency Assistance Programs: Helping communities with immediate recovery needs, such as levee repairs or debris removal.
Many of today’s flood control projects were built in response to historic flood events, and USACE continues to work with communities to enhance flood protection and preparedness for future storms.
Conclusion
The Cumberland River is not just a waterway; it is a dynamic system that supports millions of people and multiple industries. USACE’s role in flood risk management, hydropower, and navigation is a continuous balancing act, requiring expertise, coordination, and constant monitoring.
Each high-water event reinforces the importance of a well-managed system, and the lessons learned from past storms guide improvements for the future. While no system can prevent all flooding, the U.S. Army Corps of Engineers Nashville District remains committed to reducing risks, improving resilience, and ensuring the Cumberland River system continues to serve and protect the region for generations to come.
| Date Taken: | 03.28.2025 |
| Date Posted: | 03.28.2025 12:23 |
| Story ID: | 494005 |
| Location: | NASHVILLE, TENNESSEE, US |
| Web Views: | 31 |
| Downloads: | 0 |
This work, Managing the Cumberland River: How the Corps works to reduce flood risk, by Michael Davis, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
Army Corps of Engineers
