The failure of the Laurel Run Dam in Johnstown in July 1977 after 11.5 inches of rain was one of several failures in the U.S. that decade that led to the establishment of the National Dam Safety Program, through the Water Resources Development Act of 1996, according to the Altoona Water Authority's consulting engineer Mark Glenn of Gwin Dobson & Foreman and the Association of Dam Safety Officials.
A version of the federal dam safety program operates under administration of each state except Alabama, according to the association.
In addition to surveillance, warning and evacuation procedures incorporated in emergency action plans, the safety program has led to improved initial design, annual inspection of existing dams and guidelines for renovations.
The Laurel Run Dam break killed more than 40 and caused $5.3 million damage, according to the association.
It failed due to erosion from overtopping, according to a state Department of Environmental Protection website.
The rain simply "overwhelmed" the 58-year-old dam, according to online information.
"A lot of these old dams were designed based on knowledge of the time," Glenn said, speaking specifically of the failure of the Austin Dam in Pennsylvania in 1915. "They underestimated what they considered to be the maximum rainfall."
Spillways were often undersized, Glenn said.
In recent times, the National Weather Service has ratcheted up estimates of maximum precipitation, which in turn has ratcheted up size requirements for spillways, he said.
Overtopping because of inadequate spillways, debris blockage or settling of the dam top cause about a third of failures, while structural problems with the foundation, slope instability, settling or earthquakes cause a another third and malfunctioning mechanical parts like gates, conduits or valves cause many of the rest of the failures, according to the association website.
Among those killed downstream in the Laurel Run disaster were the mother, two sisters and brother of Kenny Gibson, who spoke to the Mirror in 2007, for the 30th anniversary of the 1977 Johnstown Flood, which killed 78 altogether.
Kenny was in the attic of his family's house on Cooper Avenue with them in the middle-of-the-night after 11 inches of rain from a thunderstorm, when the electricity went off, lightning glared through the vents, the house started shaking and then "just broke apart" in the surge that came down the avenue when the dam broke, he told the Mirror at the time.
The last he heard of his mother and siblings was their screaming.
Kenny, 18 then, went under the surge, got clobbered by debris and may have hit the ground, 20 feet below the raging surface.
''I thought I was done,'' he said.
He prayed, then passed out briefly near an industrial plant near the mouth of Tanneryville hollow.
Then something hit him that may have been the flood wall of the Conemaugh River, half a mile below the house.
Then he was in the river. He grabbed onto a log racing next to him and rode downstream by its side.
''I believe God spared me,'' he said.
The log kept him afloat to the waterfall at the power plant in Seward, nine miles away. He went over the falls and under the water, losing the log, but as the river turned left, the current took him close to the bank. He swam a little, grabbed an overhanging branch and hauled himself out. He crawled to a road and lay vomiting.
When he got up, he walked about a quarter mile to a house, knocked on the door and collapsed on the porch.
While he drifted in and out of consciousness, the people there took him in a pickup truck to Ligonier Hospital, where he was transferred to Latrobe Hospital. He ended up in intensive care for treatment of double pneumonia and removal of mud caked in his sinuses and ear passages.
Miraculously, he broke no bones.
The family's mixed-breed dog, Peppy, who'd been in the attic with them, was found stranded by the flood 18 feet high in a tree near Seward. Peppy was covered in burrs and mud but ''went nuts'' when he saw Kenny's father, who had been at work when the flood came.
Searchers found the bodies of Kenny's mother and siblings in various locations over a week - one in the Conemaugh Dam lake, 34 to 42 miles away.
The failure of the Teton Dam in Idaho in 1976 as the reservoir behind it filled for the first time also contributed to creation of the safety program.
As stated by a Department of the Interior report about the failure, which killed 11 and caused $1 billion in damages, "The lessons learned from this and other investigations will be of immeasurable value if they prevent the occurrence of other such disasters."
The failure occurred because of water leaking through the foundation, due to a flawed grout seal or hydraulic fracturing or both, according to the report.
Most people who live within an inundation zone may not worry, but that doesn't mean those responsible for the integrity of dams rest easy.
Viewing a succession of pictures taken as the left side of the Teton dam melted away like a partially baked cake cooling on a rack, it's easy to imagine oneself as a project engineer witnessing the dissolution of the massive work.
Neil Parrett got a whiff of that experience.
Then a staffer with the Army Corps of Engineers, he was driving with his family late one night from a vacation at Virginia Beach, heading to Washington D.C., where he worked in the Chief of Engineer office.
A teaser for a news report came on the radio about a dam that had failed in Idaho during its initial filling.
The only dam he knew that could be was the Ririe Dam, then being filled for the first time, on whose complicated volcanic foundation he'd consulted two years before.
"I went physically ill with fearful, sad, anxious emotions," he said. "What did our team miss?" he asked himself.
Half an hour later, the news came on, and he learned it was the Teton, not the Ririe dam that had failed.
He was only slightly relieved.
"[I] realized what a very vulnerable profession I was practicing," he said.
Paul Schweiger, a vice president with Gannett Fleming of Harrisburg, has heard presentations from engineers who lived through the Teton disaster.
"It was kind of surreal," he said.
"It's a humbling business," said Glenn, recalling the story of William Mulholland, architect of the water system that helped launch Los Angeles as a major city and also designer of the St. Francis Dam, which failed and killed about 500 people.
"An example of a guy who saw every success laid low by a dam failure," Glenn said.
Parrett later became involved with the Teton dam as part of the group that reviewed and reported on the failure.
He thinks "weak organizational communications, documentation and review" led to the failure, stressing that was his personal opinion.
The boundaries between the various disciplines involved in designing and building the dam were "drawn tightly," leading to a "hands-off" style of information sharing, "rather than an intertwined discussion and a documented report," he said.
That was good for efficiency, but may not have been ultimately good for the project, he said.
It made a difference, for example, that there were no "formal requirements for communication and documentation at transfer of data between disciplines responsible for site evaluation and embankment design," which meant "these specific features were not addressed for adequate treatment in the construction specifications," he wrote.
"There was very little interface between designers and constructors," he said.
Better communication among those responsible for various phases of design and construction "would have probably provided for or corrected the physical conditions that contributed to the failure," he said.
Nowadays, the permitting process is designed to help ensure the kind of reviews of "all aspects by multiple eyes" that can prevent the problems cited by Parrett, although engineers do their best with "internal checking" before anything goes out, according to Paul Schweiger, a vice president at Gannett Fleming, which is based in Harrisburg.
The lessons of the failures - resulting in better procedures and methodologies - actually enable engineers to design new dams and renovations with more confidence than in the old days, according to Glenn.
So do advances in technology, Schweiger said.
The failures also help create a sense of urgency to make things right on dams that come under an engineer's purview, Schweiger said.
It remains "serious business," he said.
The Altoona Water Authority has had its share of mandated dam renovations - and it has more to come.
In recent years, it's enlarged the spillways of the Kittaning Point, Cochran Impounding, Lake Altoona, Kettle and Plane Nine dams, according to Glenn.
Now, with recently tightened criteria, it is contemplating the need for enlarging the spillways and renewing the intakes at Bellwood and Mill Run reservoirs within the next five or 10 years.
Each of the projects cost $8 million or more, Glenn estimated.
The most common reason dams become a threat to fail is cessation of maintenance, according to Schweiger.
There are more than 85,000 dams in the U.S., more than 65 percent privately owned, and more than half needing extensive rehabilitation, according to the State Association website.
Some owners are diligent about their maintenance responsibility, Schweiger said.
Inspections often lead to recommendations for improvements.
"We generally work with dam owners," Schweiger said. "There's a lot of education going on."
Some don't have the resources, however, said Schweiger and the association website.