Flood in Union County, South Dakota

Repeated heavy rains caused record flooding of the Big Sioux River. Farmland and other lowlands including numerous roads were flooded. Some roads were damaged, and some secondary roads were washed out. A few farm homes, other farm buildings, and some fences were damaged by floodwaters. The river crested at a record 12.92 feet above flood stage at Hawarden, Iowa on June 17th. Interstate 29 was temporarily closed along a 22 mile stretch to facilitate levee building to divert some Big Sioux River water to McCook Lake, but the Interstate was re-opened when the river crested at a lower level than was feared. A levee breach across the river from Akron, Iowa, briefly aggravated lowland flooding before it was repaired.

Minor to moderate flooding of the Big Sioux River, as well as flooding of some lowlands in the county, continued through April, though flooding generally abated. Some farmland remained flooded, both near to and away from the Big Sioux River. The big Sioux River crested at about 3 feet above flood stage near Hawarden and Akron, iowa, on April 22nd. A few roads remained covered by water, and there was some road damage. High water and groundwater levels from record precipitation in the year 2010, a main reason the flooding onset was so fast in March, was also a main reason that the flooding subsided so slowly during April.

Widespread heavy rain, combined with saturated ground, caused a fairly rapid rise of the Big Sioux River to moderate to major flooding levels. Roads and numerous agricultural land near the river were flooded, as well as a few homes. A dike break just south of Big Springs caused additional farmland to be flooded. The river crested at 6.9 feet above flood stage near Akron, Iowa on September 27th.