1958 — July 2-7, heavy rain and flash flooding esp. East Nishnabotna River, Iowa –18-19

–19 EDC/NOAA. “Losses in Individual Severe Floods in the United States since July 1902.”
Climatological Data National Summary (Annual) Vol. 22. No. 13, 1971, p. 792.
–18 USGS. Summary of Floods in the United States during 1958 1964, pp. B1, B58, B61.

Narrative Information

Environmental Data Service, NOAA: “July 1958…Flash flood on East Nishnabotna River in Iowa…19 [lives lost]…$5,850 [property damage].”

USGS Abstract: “….Intense rains of July 1-2 caused record-breaking floods in southwestern Iowa. Rapid rises and the great magnitude of the floods on small streams resulted in 18 deaths and many injuries. Six towns and cities along the East Nishnabotna River and its tributaries were particularly hard hit; rural damage was also high. Total damage was estimated at $15 million.” (B1)

USGS: “Floods of July 2-7 in Southwestern Iowa

“A tremendous downpour of rain on the night of July 1-2 caused record-breaking floods in several counties in southwestern Iowa. The heaviest rains fell in Audubon and Guthrie Counties and parts of the adjoining counties. The maximum precipitation was at and to the east of the town of Audubon. The U.S. Weather Bureau rain gage at Audubon measured 12.53 inches for the 24-hour period ending at 6 p.m. on July 2. However, the total may have been greater because the gage was out of service for a time during the storm. The U.S. Weather Bureau observer estimated that the maximum 24-hour total may have been 13.23 inches. The greatest official 24-hour rainfall
previously reported for Iowa was 12.99 inches at Larrabee in June 1891.

“Nearly one quarter of the area of the State is included within the 2-inch isohyet shown on figure 18 [omitted here], compiled from published U.S. Weather Bureau reports. Within this large area were several sub-areas that experienced heavy precipitation notably the area around Audubon and an area southeast of Des Moines in which the maximum depth of rainfall exceeded 9 inches in 24 hours.

“Most of the precipitation occurred in a period of 6 hours or less, as shown by the mass rainfall curves on figure 19. The heavy precipitation in most areas began at 10-11 p.m. on July 1 and ended at 3-4 a.m. on July 2.

“As a result of the downpour, streams in the area rose rapidly to peak stages and discharges, which, in many cases, exceeded previous maximum peaks. The rapid rise on small streams came late at night, and this was responsible for the great loss of life, the injuries, and the heavy damage to property. After the floods had progressed from the tributaries to the main rivers, warnings of the impending floods averted further loss of life and permitted the removal of some property. Nevertheless, damage was great along the flood plains of the main rivers.

“The streams that were affected most by the storm were the East Nishnabotna River above Shenandoah and its tributaries above Atlantic, the south Raccoon River, the Middle Raccoon River below the confluence with the South Raccoon, and Cedar Creek, a tributary of the Des Moines River about 50 miles southeast of Des Moines. On all these streams, peak stages and discharges were at or above former maximum peaks at gaging stations and, as reported by residents of the area, exceeded all floods previously known on ungagged streams; but on the lower parts of the rivers, peak stages and discharges were far below past maximums….

“The suddenness of the great rise in stage on the smaller tributaries and the record size of the floods resulted in 18 deaths and many injuries. Total damage as the result of the flood has been estimated at $15 million. Six towns and cities along the East Nishnabotna River and its tributaries were particularly hard hit; these were: Audubon, Hamlin, Exira, Brayton, Atlantic and Red Oak. Along the Raccoon River and its tributaries, the town of Guthrie Center and parts of Des Moines were damaged by the floods.

“Rural damage was also great and consisted mostly of crop damages because the flood occurred well into the growing season, and damage to homes, fences, livestock, stored grain, and other items connected with agriculture was moderately heavy.

“Damage to transportation facilities and utilities was large. Many bridges and road fills were washed out or damaged extensively. Utilities in cities and towns that were all or partly within the flood plains of the streams were affected….” [pp. B56-B61]

Sources

Environmental Data Service, NOAA. “Losses in Individual Severe Floods in the United States since July 1902.” Climatological Data National Summary (Annual) Vol. 22. No. 13, 1971. Accessed 4-19-2023 at: https://www.google.com/books/edition/Climatological_Data_National_Summary/m_gG1xDxctMC?hl=en&gbpv=1&dq=%22Climatological+Data+National+Summary%22+december+%221955%22&pg=PA792&printsec=frontcover

Geological Survey, U.S. Dept. of the Interior. Summary of Floods in the United States during 1958 (Geological Survey Water-Supply Paper 1660-B). Washington, DC: US Government Printing Office, 1964. Accessed 4-18-2023 at: https://pubs.usgs.gov/wsp/1660b/report.pdf