Sunday, June 5, marks the 40th anniversary of the Teton Dam disaster in Idaho.

The following is from ITD Information Specialist Reed Hollinshead:

BOISE, Idaho (PRESS RELEASE) - The Teton River Canyon echoed with the sickening sound of an unstoppable force breaking through earthen defenses and finally winning the battle after several days on the offensive.

With that breach, the disaster began unfolding at noon on an early-summer Saturday.

More than 150 homes stood about six miles away. With impressive speed and brutal efficiency, all but 24 of the homes were taken from their foundations within minutes. Five of the 11 people killed succumbed in that initial surge.


Of the 23 federally declared disasters in Idaho history, this still stands as the only one that was man-made. As a result, the federal government paid out $322 million in claims over 11 years following that fateful day 40 years ago.

It introduced a new phrase to the Idaho lexicon, reflecting a worst-case scenario, especially for those nearby — “If the dam breaks.”

The dam did break on June 5, 1976.

Small leaks sprung from minor holes. The holes soon became fissures; the fissures became gaps; the gaps grew into a full-blown breach.

Two days before the dam broke, water was seeping at the rate of 100 gallons per minute. By the morning of the failure, the rate had increased to 50 cubic feet per second.

At 10:43 a.m., workers at the dam notified dispatchers of both the Fremont and Madison county sheriffs’ offices that failure was imminent. At 11:57 a.m., the dam gave way.

The first community to feel the water’s destructive power was Wilford, a community three miles wide and six miles long. The next town hit was Sugar City, then Rexburg, and then Hibbard.

More than 35,000 people were evacuated from their homes. More than 800 were treated for flood-related injuries. An estimated 3,000 were made homeless — many never found a trace of their family belongings and treasures.

When floodwaters hit Blackfoot miles away, 55-gallon barrels floated down Main Street. Before the flood subsided, a major shopping center and 150 homes there were under as much as six feet of water.

Beyond Blackfoot, the water had no more settlements to flood, though low-lying farmland was inundated. The water came to rest in the American Falls Reservoir, more than 100 miles away. It took the water two days to reach the reservoir, but for most areas, the drainage continued for another five to six days.

Highways, bridges destroyed
More than 260,000 acre feet of water spilled into eastern Idaho during the flood. Approximately 20 miles of state highways and seven bridges were damaged or destroyed by rampaging floodwaters from the dam’s collapse.

Eighty percent of the area's 700 miles of county roads were destroyed. Huge sections of pavement washed away and were found later in potato fields.

In fact, part of U.S. 20 had to be cut in order to drain standing water from those fields.

Railroad ties and rails were lifted, washed away, curved and twisted. Airplanes from the Rexburg airport were lifted and smashed. Thousands of drowned cattle were found everywhere. Buildings were destroyed and shoved off their foundations. And as the water settled, mud, inches of mud, was everywhere and in everything.

Southeast Idaho District Engineer Ed Bala was in high school in Idaho Falls at the time of the flood but remembers it well.

“I recall working with most everybody else in my hometown of Idaho Falls that Saturday filling sandbags on the banks of the Snake River. I also remember city officials trying to dig diversion channels around both ends of the Broadway Bridge.”

A channel was dug around the end of the bridge to relieve pressure. A second channel was dug around the west end of the bridge and the structure was saved.

“By the time the flood reached us, it had pretty much dissipated, so we didn’t suffer damage. It was a life-altering event for people in Tetonia, Sugar City and parts of Madison County, though,” he added.

Department response
The first step the transportation department took was to close roads in the area to combat the unpredictability of the water and the path it chose. There was not a lot to do but wait for water to subside.

Keith Green had been ITD’s district engineer in eastern Idaho for about a year on that June day in 1976. He was in Washington at his in-law’s home when news of the flood hit the airwaves. In the initial panic, Green thought the dam that gave way was the Ririe Dam, and his home would have been in the path of the floodwaters.

“If it had been the Ririe Dam, we all would have been pretty wet,” Green said.

During the first few days following the flood, almost all district highway personnel stationed at Rigby were called upon to help with flood-repair operations. The full cost of repair to state highways was borne by the Federal Highway Administration from its emergency relief program.

At the height of repairs, approximately 34 ITD Division of Highways’ personnel, together with seven Federal Highway Administration people, were actively engaged in flood work.

Green said a special design section, from ITD Headquarters and other districts, began work also immediately. Within two days, ITD awarded the first contract and repairs began. The second repair contract came just a few days later. The department ultimately spent an estimated $15 million that summer and the next rebuilding the roads.

“I worked on ITD survey crews in my college years (1978-1980),” Bala said. “Even then, the engineers and technicians in the office were still administering contracts to rebuild roads in Madison County.”

It could have been much worse
The dam broke on a weekend, when most people were still home and able to react. Because it was warm, not winter weather, the water did not pack the destructive double whammy of being powerful AND cold. The area's communication system also gave people the chance to evacuate or at least pack some belongings.

The damage and the suffering could have been worse if hundreds of volunteers hadn't spent hours filling sandbags and rushing food and water to neighbors.

Also, the more heavily populated communities of Shelley, Firth and Blackfoot had been gearing up for what they knew was coming, allowing residents to begin carrying out their belongings, and making necessary preparations.

On most of the repairs, the water washed out bridge approaches but did not damage the structures, so the department was able to simply rebuild the roads where they tied into the bridges.

Silver linings often appear in the aftermath of disaster — good things often spring from those hardships. The Teton Dam disaster 40 years ago is a case in point.

The state, its people, agencies, neighbors and churches pulled together to rebuild a better, stronger southeastern Idaho.

The department again stepped into the gap to make repairs during the disasters that struck the state decades later in the '90s (floods, blizzards and mudslides), and the recent response to the massive landslide in north-central Idaho this spring, which dropped 200,000 cubic yards of material on the highway near Elk City.

Green turns 80 this fall. He retired as chief engineer from ITD in 1994 after 38 years of service. He laments the heartaches and abject difficulties of that summer 40 years gone, but remains somewhat wistful as he recalls that time and the collaboration of disparate agencies forced together by the emergency.

“It was the most exciting time of my life.”

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