Existing comment:
Guard Gate and Wall:
When Dam No. 4 was built, it created a huge pool of water known as the "Big Slackwater" section of the Potomac River. This high, deep reservoir provided a large volume of water to feed the canal, as well as relatively smooth water upstream for canal boats entering the river.
River water was essential for C&O Canal navigation, but it could also be destructive. The guard gate in front of you stored wood planks that could be lowered during floods to protect the canal below from damage. The high guard wall you are standing on also protected the canal from floodwaters.
The winch house contained machinery to operate the guard gate during floods. The original building is gone. The National Park Service built the current structure in 1970.
Today hikers and bicyclists use this high guard wall instead of the historic towpath for about a mile upstream.
Under the winch house you can see grooves cut into the limestone gate by the tow ropes. |