I visited in the 80s with some friends on the way back to Germany from our annual winter holidays near Einsiedeln. When we arrived there, there was some construction going on, no water! They had diverted it somehow. At the top of the falls there were sandbags in the river bed, so we walked across were there normally would be lots of raging water. One of my friends coined the phrase "So ein Reinfall, der Rheinfall!" "Such a flop, the Rhine Falls!" 😉