What is a navigation lock? 

A navigation lock is a structure used to raise and lower vessels between two bodies of water at different levels on a river or canal waterway.  Locks make navigating a river easier by allowing vessels to take advantage of deeper water levels provided by dams.  The first recorded lock chamber dates back to 983 AD. 

The general design of those ancient locks varies from today’s modern structures only in technology.  The major components of a lock are essentially unchanged.  Every lock has strong parallel walls on each side to hold the water; gates on each end of the walls to allow vessels in and out, as well as isolate the chamber area from the water levels outside the lock; and some device to allow water to flow into and out of the chamber.  Most locks generally operate the same way: 

  • The entrance gates are opened and the boat moves in.
  • The entrance gates are closed.
  • A valve is opened, water in the chamber is lowered (downstream) or raised (upstream) to meet the level of the water outside the chamber.
  • The exit gates are opened and the boat moves out.

The Nashville District operates and maintains fourteen projects with navigation locks.  Ten of these locks are considered “high lift” locks because they raise vessels over 55 feet from the river below the lock to lake above them.  Wilson Lock in Florence, Alabama is the highest single lift lock east of the Rocky Mountains.  A vessel locking through Wilson Lock is lifted 94 feet from the river below to the lake above the dam.

The Old Locks

From 1888 until 1928 the U.S. Army Corps of Engineers struggled against all odds to create a system of locks and dams along the Cumberland River to aid navigation and facilitate trade. The concept for these navigational aids began in the mid-19th century, but construction would not begin for nearly 50 years.

A perpetual shortage of money plagued this project from its inception until its completion. The Chief of Engineers was always asking for enough money to complete the project, and was always given a fraction of the sum requested, if any appropriations were forthcoming at all. But the engineers persisted and push ahead.

These locks and dams were cons tructed using the technology of the 19th century. Stone was quarried, cut and laid by hand. The cribs for the dams were frames built of wood, which were submerged and filled with rocks. This work was done by hand. Workers swam underwater to make repairs and feel the bottom to insure that the cribs were properly placed. Men packed down clay in the construction process with their bare feet.

Yes, there were steam dredges, trams and derricks, but these were not too far removed from the machines used by Civil War engineers. Though steam power existed, man and animal power provided the lion’s share of the power that made these locks and dams a reality. Modern innovations were utilized in the process of constructing the locks and dams. Concrete was used for some of the locks and one of the dams, but for the most part the project was built the way locks and dams had been built for centuries.

Over the 40 years it took to construct the fifteen locks and dams of the Cumberland Improvement Project the world changed greatly. The Annual Reports for the last few locks and dams mention connecting electricity and telephone lines to the locks and lock facilities.

Automobiles and trucks were becoming commonplace, the good roads movement was underway, and this new form of transportation would soon eclipse the locomotive. Even though this system of locks and dams was almost obsolete as soon as it was completed these locks were, and are, an important part of the history of the Cumberland River, Kentucky, Tennessee and the United States.

Things to remember when passing through a lock

Lockage Priority 

The Secretary of the Army has established the following priority for passing vessels through locks. Precedence for lockage is established when a craft passes the arrival point located above or below the lock.

1st priority: U.S. Government fleet vessels 

2nd priority: Commercial passenger vessels 

3rd priority: Commercial tows or vessels

4th: Recreational boats 
*When possible, recreational boats are locked after every third lockage


Approaching the lock

When approaching for lockage, stay within the navigation channel (sailing line) as marked by buoys. Head directly for the lock and slow your boat to a no-wake speed as you approach the wall. Avoid all areas prominently marked by danger buoys and fixed signs. Pay attention to lock traffic signals and all instructions from the lockmaster. 

Channels to Monitor

-Channel 16 (Frequency 156.8) is for initial contact and distress signals only   

-Channel 13 (Frequency 156.65) is a bridge-to-bridge channel and may be used only for short messages to the Lockmaster 

-Channel 12 (Frequency 156.6) and Channel 14 (Frequency 156. 7) are for routine message handling after contact has been made on Channels 16 or 13. 

Lock Safety

There are safety hazards when passing through a like. It is imperative to ensure life jackets are worn by everyone in the vessel at all times. To provide a smooth transition from one portion of the river to the other,  enter and leave the lock at a no-wake or idle speed. Wheel wash from fast entrance or exit speeds could damage the lock gate machinery or other vessels in the lock chamber. Most important, listen to the lock operator and follow their guidance! 

For more information on locking through please read How to Lock Through.