The army corps of engineers is warning of a high risk of ‘catastrophic failure’ but it is just one of thousands of similar structures across the US rated ‘high hazard’

Buckeye dam is not much to look at. It is not a towering monument to engineering like the Hoover dam. It does not contain a mighty river or spin electric turbines.

Much of the dam next to the village of Buckeye Lake in Ohio is little more than a 16ft-high earth embankment faced with concrete and steel plating to contain a 3,000-acre artificial lake. But what it lacks in height it makes up for in length – running for more than four miles – and, if the US army corps of engineers is to be believed, its potential for catastrophe.

Buckeye is rated a “high hazard” dam because of the threat to life and property it poses. That threat has been sharpened because, for decades, its earth foundations have been eaten away by the construction of hundreds of houses on top of the dam.

The army corps of engineers released a report in March warning of a high risk of “catastrophic failure” that would cause “significant economic damages and probably loss of life” as the water washed away the dam and the houses on top of it. “The resulting flooding would most probably occur without sufficient warning or evacuation time,” the report said.

“Approximately 3,000 people live within the projected dam-failure inundation zone and, if the dam were to break, face the potential of being hit by up to an 8ft wave of water, mud and debris.”

Facebook Twitter Pinterest The crumbling dam wall at Lake Buckeye. Photograph: Chris McGreal/The Guardian

The report prompted the authorities to lower the level of the lake by half, order a halt to further construction on the dam and the local council to put in place new emergency evacuation procedures. A nursery school close to the dam wall moved to new premises.

The army corps of engineers’ warning is alarming enough but perhaps even more startling is that Buckeye dam is far from alone.

The Ohio department of natural resources (OPDNR) owns 177 dams. One-third of them are deemed to be “high hazard”, a risk to life if they collapse, and those are just the ones run by the state. Thousands more are owned by municipalities, companies and individuals. More than half are considered highly or significantly hazardous.

The American Society of Civil Engineers (ASCE) in its annual “report card” on infrastructure across the US gave the country’s dams a “D” saying that the average age of the 84,000 dams monitored by the federal government is 52 years and that about 2,000 of them are in a critical state.

“Dam failures can not only risk public safety, but they can cost our economy millions of dollars in damages. For example, the Iowa Lake Delhi dam failure in 2010 cost an estimated $50 million in damages and $120 million in economic losses, and swept away half a dozen homes,” the society said.

The Association of State Dam Safety Officials estimates the cost of rehabilitating the nation’s dams at close to $60bn with those categorised as most at risk requiring $21bn in urgent repairs. At the present rate of repair, that would take decades to complete.

“The problem is so vast as to be almost overwhelming. Where do you start?” said James Evans, professor of Geology at Bowling Green State University in Ohio, who has made a study of dam failures. “There’s huge deferred maintenance issues with all of these structures and it goes back to people don’t realise a dam is an engineered structure. All engineered structures have limited life expectancies. In my field we say dams are supposed to last 60 years. There may be a few exceptions. Some of the really large federal projects out west, the big hydroelectric dams, those were over-engineered and they’re supposed to last for a couple of hundred years. But the typical dam that you find throughout most of the United States, 60 years is a good number to use.”

Facebook Twitter Pinterest House built on top of crumbling dam wall at Lake Buckeye. Photograph: Chris McGreal/The Guardian

Buckeye dam is nearly two centuries old. It was built, mostly using earth, to create a sprawling lake to feed water into the now defunct Ohio and Erie Canal. Before long, fishermen were building wooden shacks on top of the dam. They did little damage but opened the way to much larger structures.

The army corps of engineers said the dam has been undermined by the construction of more than 370 houses on it, with foundations carved into the earth, and the driving of piles holding pontoons, decks and boat cranes directly into the dam.

“Portions of the dam have been dug away to accommodate pools and patios, utilities and drainage systems for the structures that are built into the dam. All of this has weakened the dam and undermined its stability, increasing the likelihood that it will no longer be strong enough to hold back the weight of the water behind it,” the report said. “Tell-tale signs of critical weaknesses have been observed on the dam, such as significant seepage, subsidence, persistent wet areas and structural deterioration.”

Tom Pape, a 66-year-old retired US air force officer, owns a house on the dam. He said the core of the building went up in the early 1940s but has expanded. Pape has been living there for 21 years and added a bedroom, a garage and then two more bedrooms.

“I really beefed up the house structurally. There was a tilt in it where it settled away from the dam,” he said.

Outside, next to the lake, steel girders driven into the dam hold in place a large wooden deck over the water. It is also attached to the steel dam wall. His neighbour has a similar arrangement that appears to be buckling.

But Pape is sceptical of the corps of engineers report.

“You can’t say the corps and the state were in cahoots but they were in cahoots. The state wants money to rebuild the dam and the report helps them get it,” he said. “I don’t know what this house weighs. Maybe thirty or forty thousand pounds. The house lends stability to the dam.”

Evans disagrees. He said the dam has been damaged in part because construction opens paths for water to seep from the lake through the earth wall, creating ever-widening tunnels.

“Ground water flows through an earthen dam and by putting in a structure like a basement or pipelines or trees which put roots into the dam, you’re actually providing enhanced pathways where water can flow through,” he said. “One of the types of failures of a dam is called seepage piping failure and it’s where ground water flow actually causes tunnel-like features to form in the dam itself. The tunnels get bigger and bigger. They then collapse and then the dam itself fails. That’s huge. That’s the biggest problem they’re facing there, is how to deal with the seepage piping issue from all of this abuse of the structure.”

Seepage contributed to the collapse of an old earthen dam, the Kelly Barnes in Georgia, in 1977. Thirty-nine people died when a wall of water hit a religious college.

The worst dam disaster in US history occurred when heavy rain caused the collapse of an old earth reservoir dam in 1889, killing 2,209 people in Johnstown, Pennsylvania. Modifications to the dam, including the building of a road on top, were alleged to have weakened the structure. The town was hit by the failure of a different dam in 1977 which killed 40 people.

In 1972, a coal slurry dam in West Virginia collapsed during heavy rain and killed 125 people in Buffalo Creek Hollow and left more than 3,000 homeless. The same year, a breach of Canyon Lake dam in South Dakota caused the deaths of up to 237 people.

After the Kelly Barnes tragedy, then president Jimmy Carter ordered the army corps of engineers to expand beyond inspecting federal dams and begin surveying others deemed to be high hazard.

Facebook Twitter Pinterest Boat docks fitted on to the dam wall at Lake Buckeye. Photograph: Chris McGreal/The Guardian

In its report in March, the corps recommended immediately draining Buckeye Lake. The village mayor, Clay Carroll, said that was never going to happen in part because of the economic impact on tourism – the lake is a popular boating destination – and the environmental consequences.

“The idea of completely draining the lake, I think it was discounted very quickly after that report came out,” said Carroll. “But the army corps is certainly the expert in that field and I don’t think there’s very many people going to challenge their report.”

Instead, the state authorities decided to lower the water level until a new dam is built, barred new construction on the dam and closed some beaches.

“At this time of year this would be full of boats,” said Pape. “There’s nothing out there.”

Pape’s dock now rides so high above the water that his winch does not extend far enough to lower his boat into the lake.

Carroll acknowledged that the village and the state failed to pay sufficient attention to the dam. No building permits were required until the 1990s.

“There have been talks for close to 20 years that the dam needed some repairs. I’ve lived here about 40 years, since I was a child, and there’s been talk about that on and off for years. But there was nobody really policing the situation,” he said. “None of us were being good stewards of the dam and watching over it. I think when there’s a safety issue at hand, they tend to be a little more extreme, err on the side of safety. A lot of local residents disagreed and I think that’s partly why nobody did anything.”

That’s a story reflected across the US. Hard-pressed state legislatures are reluctant to allocate big budgets to repairing dams, particularly when there is opposition from local residents to large-scale construction that can go on for months and even years.

The Ohio state legislature is on the brink of approving money for a new dam at Buckeye Lake but by some estimates it could take five years before the work is complete. In the meantime local businesses are pleading for the lake to be filled once again.

A report in June by officials in counties around the lake said they stand to lose up to $160m in revenue, much of it from tourism. Buckeye Lake chamber of commerce commissioned a rival investigation to the army corps of engineers report. It claimed it is safe to raise the lake to near its full height again.

Carroll is sceptical.

“For the most part I’m supportive of the decision to keep the water low while they make the necessary repairs or build a new dam. I just hope they can expedite it to lessen the impact,” he said.

Evans is fearful the state is moving too slowly.

“Are we going to look back on this a couple of years from now and say this was a huge mistake because the dam failed and people’s lives were lost and property was damaged? Who knows at this particular point,” he said.