Floods of February 1962 in southern Idaho and northeastern Nevada

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The floods of February 10-15, 1962, were the highest known on many streams in southern Idaho and northeastern Nevada. Some of the peak discharges have recurrence intervals greater than a hundred years. The floods resulted from an unusual combination of conditions, each of which contributed to the sudden severe flooding. These conditions were an extended period of above-freezing temperatures and prolonged light rainfall, an extensive area of snow at low altitudes, and deeply frozen ground. The snow at higher altitudes did not contribute to the floods. Runoff was greatest from watersheds at altitudes ranging from 4,500 to 6,500 feet. Flooding from small tributaries with large parts of their drainage within this range rank among the highest snowmelt floods ever recorded in Idaho and northeastern Nevada. The Snake River main stem had only minor flooding. The flood damage was the greatest ever experienced in most of the flood area becaus,e of the large areas inundated and because the value and amount of improvements has increased steadily. The total damage has been estimated as more than $10 million. INTRODUCTION The floods of February 1962 in southern Idaho and northeastern Nevada (fig. 1) were the highest floods experienced in recent times and the most devastating. The flood area includes some of the most valuable agricultural and ranching land in both States and some of the most heavily populated areas in Idaho. This report presents available data collected by the U.S. Geological Survey on these floods. The data are provisional and fall short of complete coverage. Many sites for indirect measurements of peak discharge have been selected, and the high-water profiles have been marked but not surveyed. Other indirect measurements have been surveyed but not computed. The data in this report were collected as part of the cooperative programs between the Survey and various Federal and State agencies. The district engineers for Idaho and Nevada, W. I. Travis and E. E. Harris, respectively, supervised the work of the Surf ace Water Branch district personnel. Regional flood specialists, G.L.Bodhaine, H. Hulsing, and H. F. Matthai, gave technical assistance in collecting and analyzing data and in preparing the report. Six engineers from districts other than Idaho and Nevada were temporarily assigned to the flood areas to determine peak discharges as soon as possible after the flood. The field and office work of determining peak discharges by indirect methods were directed by C. A. Thomas and R. D. Lamke in Idaho and Nevada, respectively. Weather data were furnished by the U.S. Weather Bureau, and estimates of flood damage in Idaho were furnished by the U.S. Army Corps of Engineers. Data presented in this report include: descriptions of the cause, extent, and effects of the floods; hydrographs, table of mean daily discharges and discharges at indicated times for selected gaging stations; damage figures; peak stages and discharges for the February 1962 floods and for previous maximum floods at selected gaging stations; peak discharges at miscellaneous sites; and whatever data are available for the incomplete indirect measurements. FLOODS OF FEBRUARY 1962 IN SOUTHERN IDAHO AND NORTHEASTERN NEVADA INDEX MAP OF FLOOD AREA