U.S. Floods of 1970

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

Excessive rain falling on snow during January and February was responsible for flows in the Sacramento River in California that were the highest since construction of Shasta Dam. The death toll was 18, and there was $38 million in damages. There were also record maximum discharges in the lake basins of northeastern California. Additional flooding extended from northeastern California to northeastern Oregon.

Extensive flooding occurred in early March from northeastern Louisiana across north-central Mississippi and again later in the month from Mississippi across Alabama and into southern Georgia. Highest recurrence-interval floods (50 year) occurred on streams in southwestern Georgia.

The Red River of the North in North Dakota and Minnesota was above flood stage from April 10 to May 10 as a result of melting of a deep winter snowpack and recurring precipitation. Record stages also occurred on the Des Lacs River at Foxholm, in northwestern North Dakota. Excessive rain and flooding from May 8 to 14 resulted in 21 counties in North Dakota and 11 counties in Minnesota being designated as disaster areas. A greater than 50-year recurrence-interval flood on the Deep River at Deep River, Iowa, occurred on May 14. Flash floods in extreme northwest Iowa on May 28 caused extensive damage.

During September 4-6, the "Four Corners" area of Arizona, Colorado, New Mexico, and Utah was subjected to monsoon-type thunderstorms that created flash floods over a large area. There were 23 deaths and $10 million in damages.

During October 5-10, the eastern two-thirds of Puerto Rico was subjected to excessive rainfall from a stalled tropical storm. As much as 38.4 in. of rain fell in Puerto Rico over a 6-day span. Eighteen persons lost their lives as a result of flooding, and damages were estimated at $68 million.

Source: USGS.