The Stone Arch Dam

The Jones Falls dam was constructed during 1831 and 1832 to flood a long series of rapids and falls as part of a 124-mile navigational waterway between Lake Ontario and the Ottawa River. In those days, relations between the United States and British North America (now Canada) were less than ideal and it was decided that an alternate, defensible shipping route had to be established to bypass the St. Lawrence River where it formed part of the international boundary.

Ironically, this canal now provides a most convenient and enchanting route for Americans to invade, by boat, the nation’s capital city of Ottawa. The Rideau Waterway, as it is widely known, is the oldest continuously operating canal on the continent.

Unlike most other dams, this one does not depend on gravity to hold it in place and keep it together. The stone courses cannot be lifted and separated by water and ice penetrating between them, but actually become stronger as they are pressed into each other and against the natural rock inclines on each side. This is the same concept as the arch of a Roman aqueduct transferring the weight of the water into the unmovable ground.

Another (unintended) engineering feature occasionally provides an unexpected delight for some—they hear the dam whispering to them! From the viewing platform, visitors have reported hearing voices coming from within the dam. (Of course, the locals know that by standing next to the dam on the opposite bank and speaking softly, their words may be heard more than 300 feet away). The dam was designed with a constant radius curve, which tends to carry sound waves across its face.