Ohio River Navigation Dam No. 50 Sign – Marion, Kentucky
Signage from a defunct navigation dam (no. 50) located on the Ohio River, near Marion, Crittenden County, KY
The Ohio River Lock and Dam System is a critical infrastructure network designed to regulate water levels and facilitate navigation along the 981-mile-long Ohio River. Managed primarily by the U.S. Army Corps of Engineers, the system consists of a series of locks and dams that maintain a consistent channel depth, allowing for the safe and efficient passage of commercial barges, recreational boats, and other vessels. Prior to modern improvements, the river was unpredictable, with natural shallows and seasonal variations making navigation difficult. The system, initially developed in the early 20th century, replaced outdated wooden wicket dams with more advanced high-lift structures that provide year-round navigability. Today, the system supports billions of dollars in commerce, primarily transporting coal, petroleum, steel, and agricultural products.
The lock and dam system works by creating a series of controlled pools along the river, allowing vessels to “lock through” from one water level to another. Each lock chamber is a large, enclosed space with gates at either end that open and close to let water in or out, raising or lowering boats as needed. Notable installations include the Markland Locks and Dam, McAlpine Locks and Dam, and Olmsted Locks and Dam, the latter being the most advanced and expensive project in the system. In addition to navigation, the system plays a key role in flood control, water supply, and hydroelectric power generation, benefiting communities along the river. Continuous modernization efforts ensure the system remains efficient, as aging infrastructure and increasing traffic demand ongoing improvements.