The flash flood that occurred on July 26th, 2007 in Jensen Canyon up Fish Creek Road in Wilson, WY washed out a private road and overturned two vehicles. No one was injured.
Probably the most infamous flash flood in Teton County's recorded history is the Kelly Flood. On June 23, 1925, part of the northern face of Sheep Mountain became unstable after weeks of heavy rain and slid into the Gros Ventre River. The 50 million cubic yards of sedimentary rock formed a natural dam 200 feet high and 400 yards wide that created Lower Slide Lake.
On May 18th, 1927, a portion of the natural dam broke causing a flash flood to rush down the Gros Ventre river. The flood was at least 6 feet deep for at least 25 miles downstream, and wiped out the town of Kelly which was 6 miles downstream. Six people died, and many others lost everything they owned. gros-ventre slide from shadow mountain.
Fifteen miles downstream in Wilson,WY, 6 feet of water inundated the town and hundreds of farm animals died. In narrower sections of the Snake River near Hoback, flood waters rose as much as 50 feet. The next day the waters reached Idaho Falls,ID and covered lowland sections there. When all was said and done, damages totaled $500,000 which would be over 27 million in today's dollars. You can still see the bald rock on the north face of Sheep Mountain (Sleeping Indian) as a reminder of this tragic event (Windows Into the Earth; Smith and Siegel, 2000).