At the time of this writing, the Corps is scrambling for political cover, repeatedly denying that it had any advance warning of the potential for this catastrophe. The official word is that everything was just fine until unexpectedly heavy spring rains pushed the system past the tipping point.
On February 3, 2011, a series of e-mails from Ft. Pierre SD Director of Public Works Brad Lawrence sounded the alarm loud and clear. In correspondence to the headquarters of the American Water Works Association in Washington, D.C., Lawrence warned that "the Corps of Engineers has failed thus far to evacuate enough water from the main stem reservoirs to meet normal runoff conditions. This year's runoff will be anything but normal."
In the same e-mail, he describes the consequences of the Corps failure to act as a "flood of biblical proportions." His e-mails were forwarded from Washington, D.C. to state emergency response coordinators nationwide. The Corps headquarters in Omaha, NE which is responsible for the Missouri river system, claims they heard no such warning from Lawrence or anyone else. Considering the wide distribution of this correspondence, and the likely reactions from officials in endangered states, their denials strain credulity.(bold mine)
Whether warned or not, the fact remains that had the Corps been true to its original mission of flood control, the dams would not have been full in preparation for a "spring pulse." The dams could further have easily handled the additional runoff without the need to inundate a sizeable chunk of nine states. The Corps admits in the MWCM that they deliberately embrace this risk each year in order to maximize their re-ordered priorities.
MWCM (Sec 7-07.2.6):
Releases at higher-than-normal rates early in the season that cannot be supported by runoff forecasting techniques is inconsistent with all System purposes other than flood control. All of the other authorized purposes depend upon the accumulation of water in the System rather than the availability of vacant storage space. [Emphasis added.]