Skeletal remains
Amongst the rocks and debris from the Falls, were the skeletal remains of two people. This was something of a surprise to the engineers, who had expected to find many more bodies. Between 20 and 30 people die going over the Falls each year, usually from their own hand, and usually on the Canadian side of the border.
So perhaps draining Horseshoe Falls would have resulted in more remains being found and identified. It is also possible that the force of the water had worn evidence away. Sadly, it is estimated that around 5,000 bodies were found between 1850 and 2011 at the bottom of the Falls.