The high plateau around Twin Falls, ID was scrubbed of all topsoil when the dam holding back Lake Bonneville gave way. The flood data in that region are astonishing. “The flood emptied the top 107 meters of water from Lake Bonneville , an estimated volume of 4,750 cubic km of water. The peak discharge from the Red Rock Pass outlet is estimated to have lasted for about 8 weeks and to have been about 500 times that of the maximum discharge ever recorded from the Snake River at Idaho Falls.”
Yep, that was quite an "instant irrigation project." It really changed the morphology of the region. I don't know how old you are but maybe you recall a huge patch of tumbled and rounded basalt rocks that the receding waters dumped near Bliss, ID. The guy who owned the Fearless Ferris gas stations posted a sign for weary tourists to enjoy: "Petrified watermelons -- take one home to your mother-in-law."
There were many similar floods during the Big Melt when the Pleistocene glaciers turned back to liquid water. I'm sure that's the source of the "Great Flood" stories that persist in many cultures around the world.