Dam 5 at Mile 106.6 on the Chesapeake and Ohio Canal towpath

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Dam 5, a guard lock, and a lockhouse are located at Mile 106.6 on the Chesapeake and Ohio Canal towpath. There is parking at the site. See the Locks and Lockhouses web page for an interactive location map.

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The complex of structures at Mile 106.6 on the Chesapeake and Ohio Canal towpath includes a dam, a lockhouse, and a guard lock that once let water into the canal. This is often mistaken as Lock 45, but Lock 45 is a half mile farther upstream. The lockhouse was the home of the man who managed the dam and guard lock.

Upstream view of the Dam 5 guard lock, Chesapeake and Ohio Canal National Historical Park

Dam 5 was built in 1835 but was originally made of stone and wooden cribbing and suffered constant damage from flooding. Tired of making repairs, the C&O Canal Company built a permanent masonry dam in 1860. By causing the waters of the Potomac to pool behind it, essentially forming a small lake, it served two purposes. First off, the excess water was used to supply the canal with water even in times of drought. The water was diverted into the canal, passing through the guard lock that could be opened and shut to regulate the water flow.

Secondly, the upstream water level was now constantly high enough for boats to travel directly on the river between the dam and Lock 45. This is called slackwater, and it saved the C&O Canal Company the expense of having to dig a canal. Boats traveling upstream would pass through the Dam 5 guard lock and enter the Potomac River until reaching Lock 45, where they reentered the canal. Of course, boats traveling downstream exited the canal at Lock 45 and reentered at the dam.

While it would appear to be a money saving decision, there was a technical reason for the canal bypass as well. Between Lock 45 and Dam 5 is a cliff, and it would have been impossible to blast a canal into the rocks. In fact, the towpath between the two is a concrete path that hugs the rock walls. Mules still pulled the boats while on the river, thus the need for a towpath.

Concrete towpath cut into the cliff along the Potomac River between Lock 45 and the Dam 5 guard gate on the Chesapeake and Ohio Canal

The upstream end of the guard lock is now filled with concrete to keep the waters of the Potomac River from entering the canal.

Concrete capped upstream end of the Dam 5 guard lock on the Chesapeake and Ohio Canal

On the downstream side of the canal, a concrete wall—a dam itself in some ways—now keeps the Potomac from flooding the canal during times of high water. This was installed by the National Park Service after a flood washed away the towpath in 1996. The current towpath runs across the top of the wall.

Concrete wall at Dam 5 on the Chesapeake and Ohio Canal keeps the Potomac River at bay during times of high water

Towpath south to Georgetown near Dam 5 at Mile 106.6 on the Chesapeake and Ohio Canal towpath

Downstream view from the Dam 5 guard lock at Mile 106.6 on the Chesapeake and Ohio Canal towpath

On the hill above the guard lock is a lockhouse, which was the residence of the man who was hired to operate the dam and guard lock. In addition to a yearly salary, he and his family—almost all lockkeepers were family men—had use of an acre of land for farming. Those who tended multiple locks got extra money per lock, up to two.

Operating the lock was a year-round, 24-hour-a-day job. When a canal boat approached, the captain would blow a whistle to notify the lockkeeper. If it were nighttime, somebody had to wake up and go to work. Of course that’s the benefit of being a family man—your kids had to get up for the late night and early morning arrivals!

The house is not open to the public.

Lockhouse above Dam 5 at Mile 106.6 on the Chesapeake and Ohio Canal towpath

If you look across to the other side of the dam in West Virginia, you will see a building that is a hydroelectric plant. This originated as a mill. When the dam was built, Edward Colston made an agreement with the C&O Canal Company to use the water provided by the dam to run a sawmill and gristmill. The Colston family operated the mills up until the late 1870s. The property was eventually purchased by the Potomac Pulp Company and the mills were converted into paper mills, operating from 1887 to 1891. After this the complex was purchased by the Martinsburg Power Company, and the water was used to fuel a hydroelectric power plant. Since that time the plant has been bought and sold by various energy companies and is still operating today.

Dam 5 on the Chesapeake and Ohio Canal with the hydroelectric plant at the far end

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