40 Years Later, Remembering Idaho’s Teton Dam Collapse

By Luke Ramseth and Bryan Clark

IDAHO FALLS, Idaho (AP) — Phone lines were knocked out. Highways were blocked. What Idaho residents heard on June 5, 1976, over the only reliable form of immediate communication — the radio airwaves — was incomprehensible.

“The dam has busted,” Don Ellis said on Rexburg station KRXK.

As the world soon learned, the 305-foot-high Teton Dam had broken in half. Its collapse sent a wall of water through the Teton River canyon, north of the town of Newdale in Fremont County. Downstream, with no canyon to contain it, the flood fanned out for miles across the Snake River Plain. The water turned south, gobbling up cattle, cars and homes on its slow march to Idaho Falls and beyond.

Forty years later, many Eastern Idaho residents vividly recall the chaos set in motion that sunny Saturday morning. Eleven people died and thousands more were displaced in the flood, considered the worst man-made disaster in Idaho history. Crops were ruined and thousands of livestock were killed. Total damage estimates reached $2 billion — $8.4 billion in today’s dollars.

A June 6, 1976, aerial photo shows the Teton Dam on the Teton River, near Idaho Falls, idaho, which crumbled sending thousands of gallons of water flooding down toward several small cities. More than 38,000 acres of farmland were flooded, and thousands of dollars damage was inflicted on several towns. (AP photo/mbr)
A June 6, 1976, aerial photo shows the Teton Dam on the Teton River, near Idaho Falls, idaho, which crumbled sending thousands of gallons of water flooding down toward several small cities. More than 38,000 acres of farmland were flooded, and thousands of dollars damage was inflicted on several towns. (AP photo/mbr)

And almost nobody saw it coming. In fact, when people heard initial reports, they refused to believe it.

“Naturally, I thought it was a hoax of some kind,” said John C. Porter, then the mayor of Rexburg, in an LDS church oral history. “We had lived in the shadows of dams for years in Idaho, and nothing had ever happened.”

On the Scene of the Collapse

The Teton Dam had been finished for less than a year when it collapsed. Its 17-mile-long reservoir was nearly full.

The first hints of trouble came as the new reservoir continued to fill in the early days of June. An inspection team noticed on June 3 that water was seeping from the ground at several locations downstream from the dam. At 7am June 5, workers noticed the first seep on the dam face itself. By midmorning, a large wet spot had formed.

Jay Calderwood, a heavy equipment operator, helped build the dam. At 10:30am on June 5 he got a call at his Victor home. After racing to the scene, he drove a bulldozer onto the top of the dam to try to stem the leaking, according to an account he gave for the Teton Oral History Program, a joint effort to document the disaster by Ricks College (BYU-Idaho), Utah State University and several foundations.

“I don’t think we can stop it,” Calderwood remembered thinking.