Aug 1, 2011
A record rain event in May in eastern Montana combined with high water from storms in April and May, plus snow melt from a much above normal snow pack, all contributed to bring record high water to the Missouri River chain of reservoirs by late Spring. Then residual snow melt and additional rains produced record 13.8 million and 10.0 million acre feet of runoff above Sioux City in June and July respectively. This helped contribute and sustain record releases from the Missouri River Reservoirs f
Source: NOAA National Weather Service Storm Events Database (event 322988). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Monona County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.