Chesapeake & Ohio Canal, Stop Lock at Dam No. 4, 85.62 miles above tidewater, Sharpsburg, Washington County, MD

Significance: The Stop Lock at Dam Number Four served to prevent back flooding of the canal above the dam during periods of high water and also served to prevent the loss of water from the canal during emergencies below the dam, both of these being accomplished by the lowering of a temporary timber gate into the canal bed. Only the abutments remain at the present time, the frame windless shed, previously recorded by H.A.B.S., has since been removed. The Stop Lock was probably completed prior to 1835 as the canal was in operation to a point above Dam Number Four by that date.
Unprocessed Field note material exists for this structure: FN-123
Survey number: HABS MD-223
Building/structure dates: before 1835 Initial Construction