Niagara Falls — Dewatered in 1969

Today, a walk across Niagara Falls is a daredevil’s game. In June 1969, though, less-gutsy visitors got the chance to play by sneaking across the “dewatered” American Falls.

As part of a project to study erosion of the Falls, the U.S. Army Corps of Engineers constructed a 600-foot cofferdam to block the flow of water from American Falls and redirect it to Horseshoe Falls, which then — as now — accounts for 90 percent of Niagara Falls’ flow.

The objective was primarily aesthetics. At the time, the International Joint Commission — a U.S.-Canadian agency governing trans-boundary waterways – estimated that American Falls was receding at the rate of about 3 feet per year. Large rocks were gradually accumulating at the base of the falls, causing worry that these majestic falls would erode into a sloping cascade.

While American Falls was dewatered, the opportunity to walk across proved too irresistible for visitors to resist. One onlooker recalled only a flimsy chicken-wire fence constructed to block access to the dry riverbed, which people brazenly stomped to the ground to walk from Prospect Point to Goat Island.

After six months of study, geologists estimated a cost of $1 million to $10 million to remove rock from the base of American Falls, depending on how much was removed. They considered also diverting more of the river’s flow to American Falls — to preserve the appearance of whitewater and mist — at a price tag of $6 million.

Both options were determined too expensive, the project was shelved and American Falls continues to steadily erode.