In 1969, as a young 25 year old, I managed the Sheraton Foxhead Hotel (now renamed the Sheraton by the Falls) located directly across from the American Falls.
It was from June until November of that year that the U.S. Corp of Engineers completely blocked the flow of water over this falls to determine how to prevent this falls from becoming a series of rapids. As a result, the water going over the falls was reduced to a trickle.
Most of us in the tourism industry thought this de-watering would increase the number of visitors to the falls. Boy, were we wrong. It had the opposite effect. It turned out to be one of the poorest years for tourism visitation ever.
By December, 1969, water was allowed to flow over the falls again. After studying the results of the survey, it was decided in the mid 70’s not to make alterations to the American Falls and nature was allowed to take its course. The visitors returned once again.
Check out the accompanying photo and Goggle “De-watered American Falls” to learn more about this Niagara happening.