Flood — Mills, Iowa

2011-08-01 to 2011-08-31 · near Pacific City, Mills, Iowa

Event narrative

Flooding along the Missouri River, which had gradually worsened over Mills county during June and July, persisted into August. However, conditions began improving by the end of the month as record releases from Gavins Point Dam were gradually reduced during August, especially by the end of the month. 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. By the end of August the river had fallen to around 30 feet. The flooding affected farmland along the river along with roads and recreational areas. The water treatment plant and wellheads near Glenwood were sandbagged to prevent flood waters from reaching it. By the middle of June about 125 of the 500 residences along the river had left their dwellings. Although river levels were falling by the end of August, minor flooding persisted into September. The Iowa Farm Bureau Federation estimated that the flood event caused total crop and economic losses of $22.2 million in Mills county.

Wider weather episode

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 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 the month which help alleviate some of the flooding. The flooding continued into September but moderated greatly. By the end of September the Omaha district of the U.S. Army Corps of Engineers estimated it spent $56 million directly and indirectly in battling the river throughout its share of the basin. 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.

View location on OpenStreetMap → (41.0737, -95.8955)

Source: NOAA Storm Events Database, event_id 323003. Narrative written by the NWS forecast office that issued the report.