The flood of April 1952 on the Mississippi River between the Minnesota and Des Moines Rivers established many record-high stages. In the Minnesota River basin, the floods of April 1952 exceeded those of 1951 in many locations but generally were smaller than those of 1881. The timing of flows on the Mississippi and Minnesota Rivers was favorable for the highest possible peak flow at and downstream from St. Paul. Below the Wisconsin River, the 1951 and 1952 floods on the Mississippi River were of approximately equal size.
The experiences gained in fighting the flood of 1951 proved valuable in preventing much flood damage in 1952. Because the floods generally moved slowly, few lives were lost, and there was ample time for construction of emergency levees. Many urban areas flooded in 1951 were not damaged by floods of equal or greater size in 1952. The total flood damage in the Mississippi River basin above Keokuk, Iowa, was estimated by the Corps of Engineers to be $19,376,000.
Snow surveys made during mid-March did not show conclusively that major floods were to be expected. The snow surveys showed small areas of high water content at the headwaters of both the Mississippi and Minnesota Rivers and above-normal snow cover over most of the upper Mississippi River basin. Heavy snowfall occurred over most of Minnesota, especially in the southern part, on March 22-23, 1952. Cold weather delayed the breakup until a period when more rapid melt was probable. These factors definitely set the stage for the floods. A rapid rise in temperature at the end of March and early April started the melting of the snow. Because the topsoil had been frozen when wet during the preceding fall, very little of the snowmelt was absorbed by the ground. Runoff in southeastern Minnesota occurred earliest and with greatest rapidity; the Root River crested at Rushford on March 31. Runoff in the Minnesota River basin occurred later and at a slower rate.
Floods on the Red River of the North and its tributaries above Fargo occurred during April 1952 and were due to the same factors that caused flooding in the Minnesota River basin. Because the snow cover was light in the drainage basin north of (below) Fargo, flooding was serious for only that part of the basin at and upstream from Fargo. The 1952 flood on Red River of the North at Fargo was the greatest since 1897, and flood damage for the basin was heaviest in the urban area of Fargo-Moorhead.
The 1952 floods in the upper Mississippi basin occurred 1 year after the greatest floods known in the area since 1881. The 1952 stages and discharges on the Mississippi River from St. Paul to the Wisconsin River slightly exceeded those of 1951; below the Wisconsin River, the stages and discharges of the 2 years were about equal. The similarity in the hydrographs of the 1951 and 1952 floods along the Mississippi River between McGregor and Keokuk, Iowa, is interesting and revealing. Forecasts of the 1952 flood events were accurate and timely, owing to the experience gained in 1951.
The flood crests on the upper Mississippi and the Missouri Rivers nearly coincided at St. Louis. Because the Missouri crest reached St. Louis about 2 days before the Mississippi crest, the peak discharge at St. Louis was not exceptional.