Big Slackwater Restoration Project

Big Slackwater Ground Breaking Ceremony
Groundbreaking ceremony for the Big Slackwater Restoration project in 2010.

NPS Photo

Big Slackwater was reopened to the public in October 2012. Please visit today to enjoy the natural wonders of McMahons Mill and Big Slackwater!

river construction 1
Construction for the new section of towpath was completed by barges in the river.

NPS Photo

With little maintenance between 1924 and 1971 when the National Historical Park was created, this stretch of the towpath was particularly vulnerable to flood waters. In 1996 two large floods dealt a devastating blow completely washing away long stretches of the towpath causing all towpath visitors to endure a 5-mile detour. Since then the enormity of the erosion prevented the repairs to Big Slackwater making it the only segment of the 184.5-mile canal towpath closed to park visitors.

Restoration of the Big Slackwater area is a culmination of more than 15 years of work by park staff, citizen stewards and park visitors. This project reestablishes the continuity of the entire 184 ½ mile towpath. Restoration of the towpath to its original alignment along the Potomac River and above Dam No. 4 not only eliminates the hazardous detour along narrow country roads but it restores the magnificent views and historic route walked by mules and canawlers.

The Big Slackwater restoration contract was over $19 million and was primarily funded through the American Recovery and Reinvestment Act and the Maryland Department of Transportation's Transportation Enhancement Program, with donations from the C&O Canal Association, Washington County, Town of Williamsport and the Hagerstown and Washington County Convention and Visitors Bureau.

The project was completed as of September 22, 2012. Visitors can access Big Slackwater via McMahons Mill. Use extreme caution riding this section as it is very narrow and there are no guard rails. Obey the speed limit and slow down when passing others to avoid accidents.

Last updated: July 21, 2020

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Contact Info

Mailing Address:

142 W. Potomac St.
Williamsport, MD 21795



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