Water-Supply Paper 2502

Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 Through 1989

Summary of Significant Floods, 1970 Through 1989, by State or Territory

In addition to the specific flood data, this section provides a description of the hydroclimatology and a summary of significant floods for each State or territory in the United States. The summary of significant floods includes those with loss of life or excessive damage during the period 1970 through 1989. The floods that were in the top 5 percent of each streamflow-gaging station's record during this period are tabulated, and an estimated recurrence interval is provided along with other pertinent data. A map of each State or territory is supplied to locate the streamflow-gaging stations.

Idaho

Hydroclimatology

Significant Floods

Idaho's largest flood during 1970-89 occurred in June 1986. Streamflow-gaging stations on the Cub River and several other tributaries of the Bear River recorded record floods. The maximum discharge of the Cub River near Preston (station 10093000, table 13) exceeded the 100-year recurrence interval. The discharge of the Bear River may have been the largest since 1907. Twenty-three percent of the streamflow-gaging stations recorded significant discharges during this flood.

Nineteen percent of the streamflow-gaging stations in the State recorded significant discharges during the flood of June 1974. This flood was the largest of record for the entire Salmon River Basin. The maximum discharge on the Little Salmon River at Riggins (station 13316500, table 13) of 12,600 ft³/s was only slightly less than the maximum discharge of the historical flood that occurred in June 1894.

In June 1976, the failure of the Teton Dam caused unprecedented flooding on the Teton and Snake Rivers in eastern Idaho. The flood caused 11 deaths, $400 million in damages, and left 25,000 people homeless (Paulson and others, 1991).

The flood of May and June 1984 caused significant discharges at 20 percent of the streamflow-gaging stations. Flooding was a result of rapid runoff from the melting of thick snowpack in eastern and central Idaho.

The location of streamflow-gaging stations in Idaho that had significant floods for 1970-89 is shown in figure 34 by station number. The specific data for each significant flood are listed in table 13). A significant flood is one that ranks in the top 5 percent of all annual maximum discharges for that station's period of record.

References