This is a continuation of the book Sixteen Year Study on Minnesota Flash Floods. This document was published in January, 1988 by the Minnesota Department of Natural Resources Division of Waters State Climatology Office and the University of Minnesota Soil Science Department. That study looked at sixteen years of flash floods from 1970 to 1985. In addition, flash floods from 1986 to 2012 are included below.
The definition of a flash flood used here is the occurrence of six inches or more rainfall within a 24 hour period. The size of a flash flood is measured area in square miles over which a 4-inch or more rainfall occurs. The rationale for using this criteria is that a rainfall of six inches in a 24-hour period is near the 100-year return period in Minnesota and, second, a 4-inch and greater rainfall approximates the level at which the newspaper reports indicate increased erosion or other economic damages are associated. There are a total of 117 flash flood events documented here since 1970.