finally located my copy of John M. Barry's Rising Tide: The Great Mississippi Flood of 1927 and How It Changed America

"There are two failed visions at the heart of Mr. Barry's story: the struggle to control a river that drains more than 40 percent of the contiguous United States, and the attempt to maintain an agrarian civilization in the lower Mississippi River Valley that, its white ruling class managed to believe, combined the best elements of Roman aristocracy and American democracy. The first vision was undone by stupidity (assuming anything could have been done at all); the second proved a mask of pretension that the fury of the river ripped away as if it had been a flimsy Mardi Gras disguise."

(review author T. H. Watkins' bio of New Dealer Harold Ickes also highly recommended)