The Call That Sent Two Caterpillar D9s Onto a Collapsing Dam (1976)
Construction Legends
122,640 views
On June 5, 1976, two Caterpillar D9 operators drove onto the collapsing crest of the Teton Dam in eastern Idaho and tried to save it by pushing three-foot boulders into a whirlpool swallowing 80 billion gallons of water. They failed. The dam broke. Eleven people died. This documentary tells the untold story — the 64-year arc of Morrison-Knudsen, the company that built Hoover Dam and 150+ dams worldwide, the 1965 Fontenelle Dam cover-up that should have prevented Teton, and the operators who climbed onto D9s knowing the ground beneath them was already gone.
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Morrison-Knudsen began in 1905 with a team of horses and a single Fresno scraper. By 1954, TIME magazine called founder Harry Morrison "the man who has done more than anyone else to change the face of the earth." In 1971, five months after Morrison's death, the company signed a $39 million contract to build an earthen dam on Idaho's Teton River. The dam's core was compacted silt placed over volcanic rock riddled with caves — one measured 11 feet wide and 100 feet long. A 1974 labor strike compressed the schedule. Wet seams formed in the core. And Chief Engineer Bernard Bellport had buried the lessons from Fontenelle Dam's near-identical failure 11 years earlier. On a Saturday morning, general excavation foreman Jay Calderwood got a phone call that sent him driving 40 minutes across the Teton Range to the dam he had spent four years building. He would watch it dissolve from the cab of a D9.
0:00 The Phone Call
5:56 The $39M Teton Dam Contract
11:18 The 1974 Strike & Wet Seams
13:08 The Fontenelle Dam Cover-Up
18:57 June 5, 1976 — Minute by Minute
24:35 The Dam Breaks — 2.3 Million CFS
35:37 Calderwood's Last Words
Sources: Stene 1996, Teton Basin Project History (Bureau of Reclamation RG 115) · Chadwick et al. 1976, Report of Independent Panel to Review Cause of Teton Dam Failure · Interior Review Group 1980, Final Report · Graham 2008, The Teton Dam Failure — An Effective Warning and Evacuation (ASDSO) · Calderwood 1977, BYU-Idaho Teton Oral History Program (MSSI 2) · Grigg 1977, BYU-Idaho Teton Oral History Program (MSSI 2) · Gee 2026, Failure and Fortitude (Cedar Fort) · Robison 2026, The Teton Letters (Substack/Robison Institute) · Reisner 1986, Cadillac Desert (Viking) · TIME Magazine, May 3, 1954, "Construction: The Earth Mover"
Archival footage and photographs are used under fair use (17 U.S.C. § 107) for purposes of historical commentary and education. This video contains no paid promotions.
#TetonDam #DamFailure #CaterpillarD9 #ConstructionHistory #MorrisonKnudsen #HooverDam #HeavyEquipment #DamDisaster #Bulldozer #ConstructionDisaster #1976Flood #IdahoHistory #Engineering #DamCollapse #CaterpillarEquipment
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20 Comments
I lived in southern Idaho for a number of years and I am very familiar with the volcanic ash or loess described here. I find it hard to believe that anyone would consider that stuff suitable for fill.
I built a house on a foundation of lava rock (basalt) under 7 feet of compact loess. It was very hard until a contractor dug down through it, forming the cavity for my basement. Once loosened, and mixed with air by the backhoe running over it, it became fluid. The fluidized powder sloshed around and supported waves, ripples, and reflections.
I wouldn’t trust that stuff to hold anything up or hold back anything after being disturbed. Not worth a dam!
U. S. Interior Secretary (1977 - 1981) Cecil Andrus was also formerly (1971 - 1977) and subsequently (1987 - 1995) Idaho’s governor.
“Church historians”, i.e. the Mormon church, predominant here just north of Utah. There is an LDS college in Rexburg, with the campus on a hillside overlooking the area and not affected by the flood. It served as a center for recovery efforts during the cleanup, which my (non-Mormon) church denomination’s disaster relief agency helped with, and I volunteered with for several days or a week. I was then a teenager.
The Call That Sent Two Caterpillar D9s Onto a Collapsing Dam (1976)
Construction Legends
122,640 views
On June 5, 1976, two Caterpillar D9 operators drove onto the collapsing crest of the Teton Dam in eastern Idaho and tried to save it by pushing three-foot boulders into a whirlpool swallowing 80 billion gallons of water. They failed. The dam broke. Eleven people died. This documentary tells the untold story — the 64-year arc of Morrison-Knudsen, the company that built Hoover Dam and 150+ dams worldwide, the 1965 Fontenelle Dam cover-up that should have prevented Teton, and the operators who climbed onto D9s knowing the ground beneath them was already gone.
☕ Support Construction Legends: https://www.buymeacoffee.com/construc...
Morrison-Knudsen began in 1905 with a team of horses and a single Fresno scraper. By 1954, TIME magazine called founder Harry Morrison "the man who has done more than anyone else to change the face of the earth." In 1971, five months after Morrison's death, the company signed a $39 million contract to build an earthen dam on Idaho's Teton River. The dam's core was compacted silt placed over volcanic rock riddled with caves — one measured 11 feet wide and 100 feet long. A 1974 labor strike compressed the schedule. Wet seams formed in the core. And Chief Engineer Bernard Bellport had buried the lessons from Fontenelle Dam's near-identical failure 11 years earlier. On a Saturday morning, general excavation foreman Jay Calderwood got a phone call that sent him driving 40 minutes across the Teton Range to the dam he had spent four years building. He would watch it dissolve from the cab of a D9.
0:00 The Phone Call
5:56 The $39M Teton Dam Contract
11:18 The 1974 Strike & Wet Seams
13:08 The Fontenelle Dam Cover-Up
18:57 June 5, 1976 — Minute by Minute
24:35 The Dam Breaks — 2.3 Million CFS
35:37 Calderwood's Last Words
Sources: Stene 1996, Teton Basin Project History (Bureau of Reclamation RG 115) · Chadwick et al. 1976, Report of Independent Panel to Review Cause of Teton Dam Failure · Interior Review Group 1980, Final Report · Graham 2008, The Teton Dam Failure — An Effective Warning and Evacuation (ASDSO) · Calderwood 1977, BYU-Idaho Teton Oral History Program (MSSI 2) · Grigg 1977, BYU-Idaho Teton Oral History Program (MSSI 2) · Gee 2026, Failure and Fortitude (Cedar Fort) · Robison 2026, The Teton Letters (Substack/Robison Institute) · Reisner 1986, Cadillac Desert (Viking) · TIME Magazine, May 3, 1954, "Construction: The Earth Mover"
Archival footage and photographs are used under fair use (17 U.S.C. § 107) for purposes of historical commentary and education. This video contains no paid promotions.
#TetonDam #DamFailure #CaterpillarD9 #ConstructionHistory #MorrisonKnudsen #HooverDam #HeavyEquipment #DamDisaster #Bulldozer #ConstructionDisaster #1976Flood #IdahoHistory #Engineering #DamCollapse #CaterpillarEquipment
Subscribe for more construction history: @constructionlegends
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The 50th anniversary of the Teton Dam failure is June 5, 2026.
If you know anyone who worked on this dam or lived through the flood, we would love to hear from them. ConstructionLegends@yahoo.com