U.S. Floods of 1971

By C.A. Perry, B.N. Aldridge, and H.C. Ross of the USGS

The first significant flood of 1971 occurred in February across Nebraska, Iowa, Illinois, and Wisconsin. Significant flooding occurred on streams in eastern Nebraska, and some discharges were considered maximum-of-record floods. Ice jams caused flooding on the Rock River in northwestern Illinois on February 24.

Spring rains caused extended flooding in the Southeastern States during March. Record floods occurred in Georgia on the Ocmulgee River. Many streams were above flood stage throughout March.

Snowmelt caused flooding in Utah, Idaho, and Wyoming during May and June. Significant flooding occurred in the Green River Basin in Wyoming. The discharge on the Bear River near Smithfield, Utah, was considered a 75-year recurrence-interval flood.

Discharges having recurrence intervals of 25 to 100 years were recorded on the North Platte River in Nebraska. The floods occurred in early June as a result of mountain snowmelt upstream in Wyoming. Excessive rainfall in the basin added to the intensity of the floods.

Significant flooding occurred in southern Pennsylvania, eastern Ohio, and northern West Virginia during June and July. One of the most damaging thunderstorms in the last 50 years struck the Baltimore, Maryland, area on August 1. Streamflow-gaging stations in the area recorded discharges with recurrence intervals of 100 years. Fourteen deaths and $6.5 million in damages resulted from the floods.

Tropical Storm Doria moved along the eastern seaboard from North Carolina to Maine late in August. The resultant storm system caused rain over North Carolina for the next 2 weeks. The rains eventually spread over the entire East Coast reaching into Maine. Record floods occurred on several small streams in New Jersey and southeastern Pennsylvania.

Extended flooding occurred from September until October in Texas, Louisiana, and Oklahoma. Several storms caused flooding in Oklahoma in early September. Hurricanes Edith and Fern caused floods in Louisiana in September and October. Rivers stayed above flood stage into November.

Significant flooding occurred in western Arkansas and extreme southeastern Oklahoma on December 9-10. Damages totalled as much as $16 million. The discharge on the Trinity River near Crandall, Texas, was the second highest since 1949.

Sources: USGS.