Teton Dam Survivor Recalls the Day Floodwaters Engulfed Rexburg, 50 Years Later
REXBURG, Idaho — Fifty years ago this June, a catastrophic dam failure sent a wall of water surging through the communities of Rexburg, Sugar City, and the surrounding Teton River valley, leaving behind a trail of destruction that residents of East Idaho have never forgotten. As the nation marks its 250th anniversary, survivors of the Teton Dam failure are reflecting on one of Idaho’s most devastating infrastructure disasters.
Anita Thompson Knapp was a young girl living in Hibbard, a small community just outside Rexburg, when the earthen Teton Dam gave way on the morning of June 5, 1976. She remembers the day beginning like any other.
“It was a normal morning,” Knapp recalled. “My best friend lived across a potato field from me.”
That normalcy ended quickly. A phone call from her neighbor carried the alarming news that the dam had broken, and radio broadcasts were ordering residents to evacuate. What Knapp saw when she looked toward the approaching water was nothing like the dramatic Hollywood depictions of floods she had imagined.
“It didn’t look anything like I thought it should look,” she said. “I saw something coming towards us, but it was a long, rolling dust cloud.”
A Wave That Reached Nearly to the Rooftops
Roughly two hours after the dam’s failure, floodwater reached downtown Rexburg, rising along Main Street to nearly the height of the surrounding buildings. Once the surge dissipated, standing water in the area measured approximately five feet deep. The waterline is still visible today on the historic Romance Theater at the corner of Center and Main Street — a silent marker of how high the disaster reached.
Knapp described the moment she truly grasped the danger, watching through binoculars as the water moved toward her family’s property.
“When I saw that water coming … I thought, that’s just going to engulf us,” she said. “It’s going to completely surround us, which it did.”
The family was eventually rescued by a National Guard helicopter, which landed on a small patch of elevated ground still visible above the floodwaters on the farm. Knapp recalled the moment her father saw them reach safety.
“I remember the look of relief on his face that we were safe,” she said.
The Scale of the Catastrophe
The Teton Dam failure ranks among the most costly infrastructure disasters in Idaho history. The dam, constructed on the Teton River from compacted earth and fill material, collapsed due to a combination of extensive fracturing in the surrounding rock formations and failure within the dam’s fine-grained internal core, according to the Department of the Interior’s findings.
The disaster claimed 11 lives, wiped out thousands of head of livestock, and generated more than $300 million in federal damage claims. Total losses across the region were estimated at approximately $2 billion. In the Hibbard and Rexburg area alone, an estimated 80 percent of existing structures sustained damage.
The dam was never rebuilt. The failed structure and its reservoir remain a cautionary example in engineering and land-use discussions, and the site continues to draw visitors curious about the event’s history. For a closer look at one of the most recognized photographs from that day, see the untold story behind an iconic Teton Dam photo.
The Teton Dam failure occurred less than three miles from the city of St. Anthony and sent water rushing downstream through communities that had little time to prepare. The speed with which the evacuation unfolded — and the coordination required across multiple agencies — remains a defining chapter in Bonneville County and greater East Idaho emergency management history.
What Comes Next
As the United States approaches its 250th birthday on July 4, 2026, the Teton Dam disaster is among the Idaho historical events receiving renewed attention. Survivors like Knapp are sharing firsthand accounts that preserve the human dimensions of a catastrophe that shaped the region’s relationship with large-scale water infrastructure. No proposal to rebuild the Teton Dam is currently under consideration. For additional Idaho statewide news and historical coverage, visit Idaho News.