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Big Slackwater

The (Former) Missing Link

By Ranger Hollie

After several years at the C&O Canal's Cumberland Visitor Center, I've found that most visitors ask many of the same questions. "When did the canal operate?" "What was life like for the people working the canal boats?" "What are the conditions of the towpath?" "Can you really bike from here (Cumberland) to Georgetown on the towpath?"

It is that last question that I always hated answering. Without trying to dash their enthusiasm, I would smile and reply "Almost, ...with the exception of Big Slackwater." It had been nearly 15 years since a park ranger, like myself, could say, "Yes!"

On a map, the C&O Canal meanders from Cumberland to Georgetown, hugging the Potomac River nearly the entire way. The 10-foot wide dirt/gravel towpath was continuous, all 184.5 miles, except for one small section between mileposts 84 and 89. It is this 2.7 mile stretch, commonly known as Big Slackwater, that I pointed out to visitors as the only "missing link" along the historic canal.

Big Slackwater is downstream from McMahon's Mill. Canal boats once entered the river here as the mules continued walking along the towpath. C&O Canal Company engineers chose to utilize the pools behind Dam 4 and Dam 5 rather than dig a canal prism because of rocky cliffs along the river. In 1996, severe flooding caused extensive damage to the towpath, making this section of the historic canal impassible for over 15 years.

For pedestrians and bicyclists traveling the canal, the missing section was first seen as a nuisance. Undoubtedly, it was an inconvenience to leave the peaceful serenity of nature along towpath to bike 4.5 miles on winding and narrow country back roads. However, this missing section also represented to many visitors that, despite their best efforts, they were incapable of biking the entire 184.5 miles of C&O Canal.

But, this has now changed! In the summer of 2010, the National Park Service began reconstructing the missing section of towpath and it was completed in the fall of 2012.

This much-anticipated project signified the completion of the canal once again and the reconstruction of the infamous missing link. I am happy to finally be able to tell visitors that, "Yes! You can now explore the canal in its entirety, 184.5 miles, from start to finish."

Dam 4 and Stop Gate

Dam 4 and Stop Gate
Milepost 84.6

Guard Lock

Guard Lock
Milepost 85.8

Lock 41

Lock 41
Milepost 88.9

 McMahon's Mill

McMahon's Mill
Milepost 88.1