A record rain event in May in eastern Montana combined with high water from other storms in April and May, plus snow melt from a much above normal snow pack, to bring record high water to the Missouri River chain of reservoirs by late Spring. Then residual snow melt and additional rains caused record 13.8 million and 10.0 million acre feet of runoff above Sioux City during June and July respectively. All of this helped contribute and sustain record releases from the Missouri River Reservoirs from mid June into early August. Releases from Gavins Point Dam, which is the last in the chain, reached around 160,000 cfs by the middle of June and remained that high into early August before dropping to around 90,000 cfs by the end of that month. The releases were then held steady for several weeks in early September to help avoid sloughing of water-logged levees. So although flooding continued into September at many points along the river, it moderated greatly.  At the floods peak in western Iowa 46 miles of Interstate 29 were closed due to flooding and around 250,000 acres of farmland were inundated.  The Iowa Farm Bureau Federation estimated that the flood event caused total crop and economic losses of $207 million in southwest Iowa.

Flood in POTTAWATTAMIE, IOWA
From 01-SEP-11 00:00:00 to 11-SEP-11 18:00:00 (CST-6)
Location: LOVELAND
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flooding along the Missouri River, which had gradually worsened over western Pottawattamie county during June and July, improved during August and basically ended by Sept. 11 as the river level at Omaha fell below its 29 foot flood stage.  However, at it's peak the river near Omaha climbed to nearly 36 feet toward the end of June and remained very high into mid August. This caused extensive damage to Interstates 29 and 680 along with other roads and farm land in that area.  Other properties near the river sustained flood damage and persistently high ground water also caused damage much of the summer.

Flood in FREMONT, IOWA
From 01-SEP-11 00:00:00 to 28-SEP-11 19:30:00 (CST-6)
Location: HAMBURG
Flood cause: Heavy Rain
Property damage: 3.00M
Crop damage: 0.00K
Reported by: Official NWS Observations

Flooding along the Missouri River gradually improved over the area during September as releases from Gavins Point Dam were reduced.  The river at Nebraska City, which reached a record crest of a little over 28 feet by the end of the June, had fallen to around 20.5 feet by the first of September and finally below its 18 foot flood stage during the evening of Sept. 28th.  However, extensive flooding of farm fields, roads and highways that had occurred over the summer as levees near Hamburg and Percival failed persisted into September.  The flooding caused the closure of 24 miles of Interstate 29 and Highway 2 into Nebraska City as well as other local roads and highways.   After the flood waters receded, it was learned that Highway 2 near I29 had several areas of extensive damage, included a sink hole of 15 feet deep.  Bridge approaches along I29 were damaged just north of the Missouri border.  These roads remained closed in September.

Flood in MILLS, IOWA
From 01-SEP-11 00:00:00 to 27-SEP-11 03:00:00 (CST-6)
Location: FOLSOM
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flooding along the Missouri River, which had gradually worsened over Mills county during June and July began improving during August into September as record releases from Gavins Point Dam were reduced during August.  At Plattsmouth the river reached a crest of a little over 36 feet by the end of June, flood stage is 26 feet.  The river level near Plattsmouth fell a little in July and a bit more in early to mid August and by the first of September the river had fallen to around 30 feet.  The river near Plattsmouth finally fell below flood stage on Sept. 27th.  The flooding affected farmland along the river along with roads and recreational areas.

Flood in HARRISON, IOWA
From 01-SEP-11 00:00:00 to 18-SEP-11 17:30:00 (CST-6)
Location: RIVER SIOUX
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flooding along the Missouri River gradually improved and then basically ended over Harrison county during September as decreased releases from Gavins Point Dam allowed the river near Blair to fall below its 26.5 foot flood stage by the 18th.  However, county roads, highways and parts of Interstate 29 sustained damage from flood waters as did some homes and several parks and recreation areas near the river.   Parts of Interstate 29 remained closed during the month.