U.S. Floods of 1976
By C.A. Perry, B.N. Aldridge, and H.C. Ross of the USGS
An unusually intense winter storm hit the island of Oahu, Hawaii, on
February 7, 1976. As much as 4 in. of rain fell in some areas during a
period of 1.5 hours. Between 17 and 20 in. total fell throughout the
course of the storm. Streams draining the western slopes of Oahu's
mountains reached record high discharges.
Snowmelt during March and April caused prolonged flooding in North
Dakota and Minnesota. Warm temperatures during the last week of March
began melting an 18-in. snowpack. Flooding was the worst in the Souris
River Basin of North Dakota. As record stages were being recorded at
streamflow-gaging stations, a 6-week advance forecast of the severity of
the floods gave time to improve levee systems in North Dakota preventing
much additional damage.
On May 30, a weak cold front stalled over Tulsa, Oklahoma, for several
hours. Total rainfall of 7 to 10 in. was unofficially reported. Previous
maximum gage heights were exceeded by 1 to 3 ft at two streamflow-gaging
stations on Mingo Creek. Flooding covered a larger area and caused more
damage than any previously known flood along Mingo Creek.
The greatest flood disaster of 1976 occurred on June 5 when the Teton
Dam in Idaho failed. The Teton Dam is located on the Teton River in the
headwaters of the Snake River Basin. The dam was breached as the reservoir
was filling for the first time. About 173,000 acre-ft of water drained
through the dam in 2 hours and 23 minutes. The maximum discharge
downstream from the dam was estimated at 2.3 million ft³/s. The flood
caused 11 deaths, and damages were estimated at $400 million.
Severe floods hit the Houston, Texas, metropolitan area on June 15. The
floods were caused by intense rainfall totalling as much as 13 in, most of
which fell within a 3-hour period. The discharge of the Brays Bayou was
29,000 ft³/s, which is considered the 40-year recurrence interval. Eight
deaths and an estimated $25 million in damages resulted from the flood.
A storm producing 4 to 6 in. of rain on June 19-20 hit south-central
New York and north-central Pennsylvania. The rain produced unusually large
maximum discharges in small tributaries to the Chemung River near Corning
and in the headwaters of Catharine Creek.
On July 3 and 4, large floods occurred in southeastern Kansas. Otter
Creek and Elk River were the most affected by the 4 to 8 in. of rain that
fell during 2 days. The maximum stages on Otter Creek and Elk River were
the largest known for their periods of record. The Walnut River at El
Dorado was reported to have crested almost 1 ft above the previous maximum
The second largest flood disaster of 1976 was the Big
Thompson River flood in Colorado. The area most affected by the flood
was the Big Thompson Canyon, especially the area downstream from Estes
Park, Colorado. The flood was caused by a storm on July 31 through August
1, with rainfall amounts totalling as much as 12 in. in some areas
(National Oceanic and Atmospheric Administration, 1976); an estimated 7.5
in. of rain fell in some areas in 1 hour. Maximum discharges on the North
Fork Big Thompson and Big Thompson Rivers exceeded previously recorded
maximums at several locations. Reports of an estimated 19-ft high wall of
water rushed through Big Thompson Canyon destroying everything in its
path. In the narrows of the canyon, stream levels rose to 14 ft above
pre-flood levels and washed away 1.9 mi of highway. The flood resulted in
139 deaths and 6 missing persons, destroyed 323 homes and 96 mobile homes,
and damaged many other homes. Two counties were declared Federal disaster
areas, and the flood caused $41 million in damages.