Map It
Site Name Big Slackwater
Water BodyPotomac River
Physical AddressAt the end of Dam #4 Road, Sharpsburg, MD 21782
DirectionsFrom I-70 take exit 28 for MD-632 toward Hagerstown/Downsville. Slight left at Halfway Blvd. Left at MD-632 (Downsville Pike) south, continue on Dam Number 4 road, continue over the bridge, to the end of the road and the access point will be on your left.
Owner/Manager NameNational Park Service
Owner/Manager Phone301-739-4200
Owner/Manager Email 
CommentsThis site is located above Dam #4 which is a river hazzard. All boaters must exit the river before the Dam. Public access to the Potomac River is limited between Westernport and Big Slackwater due to dams below these locations.
# of Ramps1
# of Ramps ADA0
Ramp Width (Feet)29
Ramp SurfaceCONCRETE
Large BoatsNo
Vessel Size NotePlease note that "large boats" is intended as a general reference to ramp capacity. Generally, vessels less than 16 feet in length are considered small and those greater than 16 feet as large.
Soft LaunchYes
Soft Launch ADANo
# of Piers1
Transient UseNo
HoursOfOperationDay Light
Fee Or Permit RequiredNo
Parking Lot TypePAVED
Parking Lot SizeLARGE >20
# of Car Spaces23
# of Car Spaces ADA1
# ofTrailerSpaces14
# of Trailer Spaces ADA0
Turnaround AreaYes
Trash ServiceNo
Fuel on siteNo
Questions And UpdatesIf you have a question about this site, contact the management agency using the phone number or contact information provided above. Permit/launch fees can change without notice so this site does not list them. Any corrections or updates to the information listed here should be sent via e-mail to
Tide Information
 Map It