On May 31, 1889, the South Fork Dam near Johnstown, Pennsylvania collapsed during a large storm. The failure of this dam claimed 2,209 lives as 20 million tons of water flooded the town. Prior to the dam failure, dam safety awareness was minimal and was not widely recognized. Now, 131 years later, strong dam safety programs, investment in America’s critical infrastructure, and dedication to public-private partnerships are just as crucial. The importance of Dam Safety Awareness must continue growing to assure America’s dams are safe, resilient, and operational.
Dams in America
There are more than 90,000 dams in the United States that have been built to maximize the use of our most valuable resource – water. They serve several functions including water supply for agricultural, community, domestic, and industrial use; flood control; recreation; and renewable energy.
Water Storage – Dams create reservoirs that supply water for irrigation, domestic and commercial water supply, recreation, fire control, and more.
Flood Control – Damns aid in reduced flooding and erosion.
Irrigation – Ten percent of the water used by American cropland is stored behind dams.
Renewable Energy – Dams produce 8-12 percent of the nation’s power needs via hydropower. Without hydropower, the United States would have to burn an additional 121 million tons of coal, 27 billion barrels of oil, and 741 billion cubic feet of natural gas.
Recreation – Boating, fishing, swimming, and camping are just some of the recreational activities that take place as a result of hydropower created by dams.
Dam Safety Issues in America
Safe operation and maintenance of dams are critical when it comes to avoiding potential dam failure and disaster. With tens of thousands of dams across the country, many of which are approaching their life expectancy, it’s important to be on the lookout for dams with high-hazard potential. High-hazard potential dams climbed to more than 15,000 in 2018, and only continue to grow due to growing populations. This increase is known as ‘hazard creep’. Hazard creep describes the growth of development such as people, buildings, and businesses, that moves closer to dams.
Investing in Dams
Dams are a major piece of our country’s critical infrastructure, and investment is needed to rehabilitate those that are deficient.
Why do dams need upgrading?
Changing technical standards over time
Improved techniques for building
Increases in population
Better understanding of precipitation patterns in areas
Changing land use
Upgrading a dam when it reaches an increased hazard potential is critical for the integrity of the dam structure as well as the safety of those living in the vicinity. The problem that dam owners have (especially on the private side) is the difficulty in funding the upgrades.
The Association of State Dam Safety Officials have tracked dam rehabilitation costs for non high-hazard and high-hazard dams since 2004.
Recreational Dam Safety Awareness
Outside of critical infrastructure, dams provide recreational opportunities for boaters, swimmers, kayakers and more. Unfortunately, there are dozens of deaths on American waterways each year that take place at structures called ‘low-head’ dams.
Low-head dams are low in height and typically have a 1-15 foot drop off, allowing water to flow off the dam. Below the drop off, water falling from the dam can create circulating currents that can trap people and objects underwater against the face of the dam. The force of the water is extremely strong, and these structures have earned the title of ‘drowning machines.’
Many people are unaware of the dangers associated with dams which is why it is so important to educate communities of dam safety.
Click here to learn more about public safety around dams.
It had been raining heavily for several days in late May of 1889. People living below in the narrow Conemaugh Valley were eager for the spring rains to end. Just a month earlier, deep snow had lined the steep ravines of the Allegheny Mountains range and the ground was sodden with the heavy spring runoff. Floodwaters at the South Fork Dam high above the City of Johnstown, Pennsylvania were causing the lake level to rise, threatening to overtop the large earth embankment dam.
As the spring rains continued, life was about to change for the working-class city of 30,000 and other communities beneath the South Fork Dam.
Originally constructed in 1852, the South Fork Dam provided a source of water for a division of the Pennsylvania Canal. After a minor breach in 1862, the dam was hastily rebuilt creating Lake Conemaugh. By 1881, the dam was owned and maintained by the South Fork Fishing and Hunting Club, who created a recreational area by the large lake, enjoyed by their elite clientele from nearby Pittsburgh.
For the pleasure of their private members, club owners soon began modifications to the dam. Fish screens were installed across the spillway to keep the expensive game fish from escaping. The dam was lowered by a few feet so that two carriages could navigate the carriage road to the clubhouse. Relief pipes and valves that controlled the water level and spill off from the original dam were sold off for scrap, and rustic cottages were built nearby.
Notoriously leaky, repairs to the earthen dam had been neglected for years. As torrential rains came down, swollen waters from the lake put tremendous pressure on the poorly maintained dam. With fish screens trapping debris that kept the spillway from flowing and with no other way to control the lake level, the water kept rising.
Club officials struggled to reinforce the earthen dam, but it continued to disintegrate. When the lake’s water began to pour over the top, it was apparent that a catastrophic collapse was inevitable and imminent. Frantic riders were sent down the valley to alert the local communities and tell them to evacuate. Sadly, few residents heeded the alarm being so often used to the minor seasonal flooding from the Little Conemaugh river.
This time, however, the flood danger was much more serious and deadly.
On May 31, 1889 at 3:10pm, the South Fork Dam washed away, leaving a wake of destruction that killed 2,209 people and wiped the City of Johnstown off the map forever. It took only 10 minutes for the raging torrent of 20 million tons or about 4.8 billion gallons of water to rip through the communities of South Fork, Mineral Point, Woodvale, and East Conemaugh.
Along the way, the deluge accumulated everything in its path, including all sorts of debris—from city buildings, houses, and barns. Piles of boulders, trees, farm equipment, rolls of barbed wire, horse carriages, and railroad cars churned in the turmoil. Embroiled in the devastation were also animals and people—both dead and alive.
By the time the raging waters reached Johnstown at 4:07 pm, the mass of debris was a wave 45-feet-tall, nearly a half mile wide and traveling at 40 miles per hour.
Despite the shocking immensity of this tragedy, relief efforts to the ravaged communities began almost immediately. Emergency shelters for homeless residents popped up and the grim task of cleaning up began. Volunteers and donations poured in from across the country and world, sending tons of supplies and help. One of the first to arrive was Clara Barton, who had founded the American Red Cross just a few years earlier.
It would take months to sift through all the wreckage to find the bodies and years to fully recover from the aftermath.
It is widely thought the South Fork Fishing and Hunting Club was to blame for the catastrophic failure of the South Fork Dam. Members of the club neglected to properly maintain the dam and made numerous dangerous modifications. Lowering the dam crest to only about four feet above the spillway severely impaired the ability of the structure to withhold stormwater overflow. The missing discharge pipes and relief valves prevented the reservoir from being drained for repairs and the elaborate fish screens clogged the spillway with debris. The club had also been warned by engineers that the dam was unsafe.
A hydraulic analysis published in 2016 confirmed what had long been suspected, that the changes made to the dam by the South Fork Fishing and Hunting Club severely reduced the ability of the dam to withstand major storms.1
The South Fork Dam was simply unable to withstand the large volume of stormwater that occurred on that fateful day on May 31, 1889.
Although the South Fork Fishing and Hunting Club failed to maintain the dam, club members were never legally held responsible for the Johnstown Flood after successfully arguing that the disaster was an “act of God.”
Due to what many perceived as an injustice and outrage towards the wealthy club members, American law was ultimately challenged and “a non-negligent defendant could be held liable for damage caused by the unnatural use of land”. This legal action eventually imposed laws for the acceptance of strict liability for damages and loss.
National Dam Safety Awareness Day
On May 31st, we commemorate the catastrophic failure of the South Fork Dam by recognizing this day as National Dam Safety Awareness Day.
The Johnstown flood or the Great Flood of 1889, as it was later known as, was the single deadliest disaster in the U.S at the time. This tragedy, 129 years later, is still a harsh reminder of the critical importance of the proper maintenance and safe operation of dams.
Earth embankment dams may fail due to overtopping by flood water, erosion of the spillway discharge channel, seepage, settling, and cracking or movement of the embankment.
Routine dam evaluations and inspections, as required by law, can identify problems with dams before conditions become unsafe. Dams embankments, gatehouses and spillways, like other structures, can deteriorate due to weather, vandalism, and animal activity. Qualified engineering firms can perform soil borings, soil testing, stability analyses, hydrologic and hydraulic modeling for evaluating spillway sizing and downstream hazard potential, arrange for under water inspections by divers, permitting, and assistance in applying for funding for repairs. Also required, are Emergency Action Plans (EAP) that identifies potential emergency conditions and specifies preplanned actions to be followed in the case of a dam failure to minimize property damage or loss of life.
The required frequency of dam inspections will vary depending on the state, but generally are based on hazard classification, with high hazard dams requiring more frequent inspection. Generally dam inspections should be performed every two years for high hazard dams, unless the state requires more frequent inspections. The best time of year for inspections is in the fall, when reservoir levels are typically low, and when foliage and tree leaves are reduced, allowing improved visibility around the dam.
Halloween is just around the corner, and with it comes ghosts, goblins, and all things haunted – even dams. This year, we are taking a look at the four most haunted dams in the United States. Did we miss any? If so, let us know in the comments. Happy Halloween!
Arguably the most well-known dam on our list, the Hoover Dam has a long history of haunted happenings. Constructed on the Colorado River on the border between Nevada and Arizona during the Great Depression and one of the Seven Modern Engineering Wonders of the World, the Hoover Dam employed thousands of people at a time when it was needed most. It was not without its problems, however, as 112 workers lost their lives during its construction, although not from being entombed in the concrete during construction as promulgated by one popular urban legend. The deaths occurred in more typical ways such as falling, drowning, and being struck by equipment and debris. In addition to the 112 who perished from industrial accidents, 42 workers were said to have died from pneumonia; however, not a single non-worker in the area died from pneumonia during this time. Workers allege that the construction company made up the whole pneumonia story in order to avoid any lawsuits, as the workers had actually perished from carbon monoxide poisoning while operating vehicles inside the diversion tunnels. Considering that approximately four people per year commit suicide by jumping from the dam as well, it should come as little surprise that tales of spirits and hauntings at the dam are commonplace. There have been numerous reports of crying sounds and footsteps inside the facility, and apparitions of men wearing old-fashioned work clothes have been seen, although no photos have been captured.
Horrifying Hales Bar
Constructed from 1905-1913 primarily to hold back the whirlpools along the Tennessee River, the Hales Bar Dam in Tennessee was the nation’s first hydroelectric dam. Unfortunately, it was also built on cursed land. According to legend, Native American War Chief Dragging Canoe cursed the land on March 17, 1775 after the controversial Treaty of Sycamore Shoals was signed. He said that the land would be “dark and bloody” to any who attempted to live there. In addition, the waters surrounding the dam were considered sacred by Native Americans. In fact, Native Americans believed that they could see the souls of their ancestors being sucked into one of the largest whirlpools, nicknamed The Suck, and that any who were unfortunate enough to get too close to The Suck would be pulled down into the whirlpool by their dead ancestors. Like the Hoover Dam, legend also says that many workers fell to their deaths during the construction of the dam and were entombed in the concrete, but there are no actual historical accounts to corroborate the legend.
The construction of the dam encountered numerous issues, including soft bedrock and shale on which the dam was constructed; accidents, illnesses, racial tension, and deaths of workers; and even numerous leaks springing up immediately after construction was completed. Also, the town that the creation of the dam flooded contained the old town graveyard, and none of the bodies were disentombed. The Hales Bar Dam never functioned properly, and after a failure in the 1960s, the dam was demolished, flooding the area behind it, which included a cemetery filled with hundreds of graves of mostly children who had died during the 1918-1919 Spanish Flu epidemic. With such a strange history, it is no wonder that the Hales Bar Dam is considered a haunted hotspot. Visitors and employees have seen apparitions and shadows, have heard and seen footsteps that actually kicked up dust, and have heard children’s voices chanting and crying. Some unlucky visitors have even felt hands reach out and touch them from the whirlpool, while others have reported seeing a strange figure in the cat walk, believed to be the restless spirit of War Chief Dragging Canoe himself.
Daunting Devil’s Gate
Devil’s Gate Dam was constructed on the Arroyo Seco in Pasadena, California in 1920 as Los Angeles’ first flood control dam. Where the dam was built was a natural rock formation bearing resemblance to a side profile of a devil, hence the name. The gate, a steel structure that is part of the dam, is believed by some to be a portal to the spiritual world, with some going so far as to say it is one of the Seven Gates of Hell. The reasons for the theory are numerous. Jack Parsons, a rocket scientist who co-founded Jet Propulsion Laboratory, was a practicing occultist who believed the Devil’s Gate Dam to be a portal to the otherworld. He frequently practiced occult rituals, along with Scientology founder L. Ron Hubbard, which some say triggered the opening of the portal. They even went so far as to try to summon a “moonchild,” but were not-so-surprisingly unsuccessful. Furthering the superstition surrounding the dam was the disappearance of four children within a one-year period in the 1950s. Two of the children were never found, while serial killer and road construction worker Mack Ray Edwards confessed to killing the other two and of burying their bodies beneath the asphalt of a newly paved freeway. In addition, Devil’s Gate Dam is part of what is considered Pasadena’s haunted triangle, which includes the dam, the Colorado Street “Suicide” Bridge, and the Enchanted Forest/Cob Estate. The triangle is called Demon’s Gate, and is believed to be the driver of all spiritual activity in the region.
Constructed on the Teton River in Idaho by the Bureau of Reclamation, the Teton Dam catastrophically failed on June 5, 1976 as it was filling for the very first time. Having only 40 minutes to warn residents prior to the dam’s collapse, 11 people and 13,000 cattle perished in the disaster. Also, thousands of homes and businesses were destroyed and damages were estimated to be about $2 billion. BJ’s Bayou Restaurant was once a hotel that was destroyed during the dam failure and never reopened. It was converted to a restaurant, bar, and residence in the 1980s, and is said to have been haunted ever since its opening. Visitors tell tales of seeing the ghosts of both a young girl and an older man in uniform, both of whom are believed to have been victims of the flood. In addition, the dam itself is said to be haunted by demons as a result of occult activities that took place there, with witnesses reporting having very strongly negative feelings when they are inside the spillway. There is good that came from the Teton Dam failure, however. The Bureau of Reclamation’s Dam Safety Program was instituted in 1978 as a direct result of the disaster. Less than a year later, the Federal Emergency Management Agency (FEMA) was created, and in 1986, dam safety was addressed in the Water Resources Act. FEMA’s National Dam Safety Program, passed in 1996, was the first national legislation to address dam safety, the purpose of which is to “reduce the risks to life and property from dam failure in the United States through the establishment and maintenance of an effective national dam safety program to bring together the expertise and resources of the Federal and non-Federal communities in achieving national dam safety hazard reduction.”
There are over 87,000 dams in the United States. With one-third of those dams posing a serious threat to people’s lives and property if they fail, dam safety is nothing to ignore. Dams are a critical part of our infrastructure providing flood protection, water supply, hydropower, irrigation, and recreation. Although dam safety may not seem to be a big concern, dam failure can affect people for miles and miles, with sometimes fatal results. National Dam Safety Awareness Day is a day to acknowledge the progress we have made in making our dams safe structures and the continuous progress we still have yet to make.
As our population keeps growing, our dams are getting older and some are even deteriorating. A dam can fail within hours of the first signs of breeching. Dam safety is a shared responsibility. Dam owners, engineers, community planners, along with federal and state leaders all have important roles in keeping dams running efficiently and safely.
The National Dam Safety Program (NDSP), led by FEMA, has been working for 30 years to keep Americans safe from dam failures. The NDSP assists states in establishing and maintaining dam safety programs along with providing technical training to state and federal dam safety staff. Their support for research and development has greatly helped raise awareness about improper dam safety along with lessening the impact on a community if a dam were to fail.
Why Dams Fail
One of the most frequent ways dams fail is overtopping. Overtopping is a strong indicator of an unsafe dam. This can happen due to a number of reasons but typically it is from inadequate spillway design, debris blockage, or settlement of the dam crest. Overtopping accounts for about 34% of all dam failures in the United States and can also lead to erosion of the downstream face of the dam. Without proper maintenance of the downstream face, the dam is at a heightened risk of failure. Wind and other harsh weather conditions can cause waves to erode the upstream face which can make the dam unsafe during heavy rainfall or flash floods.
Other important factors that can cause dam failure are seepage and foundation defects. These defects account for about 30% of dam failures in the US, typically due to slide failure. If seepage or other factors weaken the soil supporting a dam, the overall strength of the dam greatly diminishes, creating the potential for a landslide-like affect.
Improper construction measures such as insufficient soil testing also contribute to dam failures. When permeable cavities or course gravel are present in dam foundations, seepage is a big concern because it erodes the soil at a fast rate. This often results in the dam settling or sinking which causes failure. A dam can fail by water passing under, over, through, or around it. Every dam should be properly connected to the ground and constructed using the best materials and methods to meet current design and construction standards.
How to Prevent Failures
When constructing and maintaining a dam, taking the proper engineering steps is vital. For example, completing sufficient soil tests prior to construction helps ensure that the dam will be adequately supported. The soil on the actual site should be examined before any detailed planning is put into place. It is also important to confirm the existence of impervious clay to seal the excavation and form the core of the bank. Failures can be prevented if the contractor is aware of any soil limitations at the site.
Dam failures have taken the lives of hundreds of people in recent decades so it is important to hire the right contractors to do the proper work. Nothing can take the place of a reliable and reputable contractor. Having experienced engineers and machine operators greatly reduces the risk of failure. It is important to review every employee’s credentials before starting a job and to always seek professional advice from an engineer when planning and designing a dam. Improper construction and inspection can lead to a weak structure, which can be dangerous and, sometimes, even fatal.
Maintenance and inspection must be routinely completed in order to keep dams safe. If a problem associated with a dam is not addressed in a timely manner, it can become more dangerous as time goes on. Dam inspectors should document every inspection in order to accurately assess needed repairs. While maintaining a dam, vegetation control, erosion repair, and clearing debris from spillways should be a routine practice. A healthy layer of grass can help prevent erosion, and any debris within 25 feet of the dam should be removed. A poorly maintained dam can cost the owner more to repair than a dam which is regularly inspected and checked for needed repairs.
Emergency Action Plans
173 dams across the country have failed since 2005 so it is important to know what your community’s Emergency Action Plan (EAP) is if a local dam were to fail. An up-to-date EAP is critical to reduce the risk of lost lives and property damage. A good EAP accomplishes three main goals: identify the area below the dam that would be flooded, establish a line of communication for the dam owner and emergency response, and provide warnings and evacuations to be conducted by local emergency teams. Below are the six essential elements of a successful EAP.
Notification Flowchart. This is to identify who should be notified by whom, and in what priority. This information is crucial for the notification of the persons in charge of taking emergency actions. The flowchart should have detailed information about each position in the chart such as title, office, and multiple ways of contacting that individual. EAPs should include the residents and businesses downstream of the dam that should be notified in case of an emergency. Proper communication and assigned roles can drastically reduce the impacts of a dam failure.
Emergency Detection, Evaluation, and Classification. This ensures that the appropriate course of action is taken based on the urgency of the situation. Having procedures in place to classify an emergency situation properly will better prepare a community to activate their EAP before a catastrophe occurs. Early detection of a potential problem can save hundreds of lives and millions of dollars in property damage.
Responsibilities. When an emergency occurs, everyone should know their role in reacting to the situation. Typically, the dam owner’s responsibilities include developing, maintaining, and implementing the EAP while state and emergency management officials are responsible for warning and evacuation. Without proper assignment of responsibilities, the EAP would be ineffective.
Preparedness. This section outlines actions to be taken before an emergency occurs. Preparedness actions are taken to moderate or minimize the effects of a dam failure and to identify specific responses to be taken in emergencies.
Inundation Maps. An inundation map identifies the areas affected if a dam were to fail. This map is important in identifying a strategy to notify and evacuate areas in danger. These maps graphically display flooded areas and show travel times for wave front and flood peaks at critical locations.
Appendices. This section contains information directly applicable to the actions of the dam owner and the emergency management parties. The appendices provide information that supports the material used to develop the EAP such as maintenance requirements and dam break investigations.
Dams serve an important role in our nation’s infrastructure. Millions of people in every state rely on dams to bring them benefits such as flood control, water supply, irrigation, recreational areas, and renewable energy. Safe operation and maintenance is important to sustaining these advantages and avoiding disasters which are very often preventable. Dams fail for a number of reasons but the primary source of failure is poor inspection and maintenance, inadequate design, and improper operation. Know your risk when it comes to dam failure in your community. Getting familiar with your community’s EAP and level of risk from a dam failure can greatly help you in an emergency situation. National Dam Safety Awareness Day is an opportunity to raise awareness about our nations deteriorating dams and to take steps in making them safer structures for our community.
This month marks the ten year anniversary of Hawaii’s Ka Loko Dam failure on the island of Kauai. On March 14, 2006, after 40 days of heavy rainfall, the rising water finally overtopped the dam near the original spillway — which had been filled in by the owner. At the time, the State of Hawaii lacked resources and legal authority to properly ensure that the owner fully addressed safety concerns. The break sent almost 400 million gallons of water downstream four miles until it finally reached the ocean, and the water reached about 20 feet in height, destroying whatever was in its path, including trees, homes, and vehicles. The disaster, which was entirely preventable, killed seven people, including a pregnant woman and child, and caused millions of dollars of property damage as well as significant environmental damage. As a direct result of the disaster, Hawaii increased funding to its dam safety program, allowing for improved regulation of local dams.
Historic U.S. Dam Failures and Legislation
Unfortunately, the Ka Loko Dam failure in Hawaii was not an isolated incident. Dam failures in the United States have caused catastrophic damage and loss of life for well over a century:
May 16, 1874 – Williamsburg, Massachusetts
At 7:20 a.m., the 43-foot-high Mill River Dam above Williamsburg, Massachusetts failed, killing 138 people, including 43 children under the age of ten. At the time, this failure was the worst in U.S. history.
May 31, 1889 – Johnstown, Pennsylvania
Over 2,200 people — more than 20% of the residents of Johnstown — perished in the flood caused by the failure of South Fork Dam, nine miles upstream. To this day, the South Fork Dam disaster is the worst in U.S. history. National Dam Safety Day is celebrated each May 31 in remembrance of the catastrophe.
Around the turn of the century, many more dam failures occurred, resulting in the passing of some early state dam safety legislation.
March 12,1928 – San Francisquito Canyon, California The failure of St. Francis Dam, which killed over 450 people and caused over $13 million in damage, the equivalent of about $180 million by today’s standards, was a landmark event in the history of state dam safety legislation, spurring legislation not only in California, but in neighboring states as well. It was also the worst civil engineering disaster of the 20th century, serving as the catalyst for the engineering licensure requirement in California.
In response to the St. Francis Dam disaster, the California legislature created an updated dam safety program and eliminated the municipal exemption. In addition, the State was given full authority to supervise the maintenance and operation of all non-federal dams. However, even in the wake of such a horrific disaster, most other states had severely limited dam safety laws — that is, until a series of dam failures and incidents occurred in the 1970s:
February 26, 1972 – Buffalo Creek Valley, West Virginia
The failure of a coal-waste impoundment at the valley’s head took 125 lives, and caused more than $400 million in damages, including destruction of over 500 homes.
June 9, 1972 – Rapid City, South Dakota
The Canyon Lake Dam failure took an undetermined number of lives (estimates range from 33 to 237). Damages, including destruction of 1,335 homes, totaled more than $60 million.
June 5, 1976 – Teton, Idaho
Eleven people perished when Teton Dam failed. The failure caused an unprecedented amount of property damage totaling over $1 billion.
July 19-20, 1977 – Laurel Run, Pennsylvania
Laurel Run Dam failed, killing over 40 people and causing $5.3 million in damages.
November 6, 1977 – Toccoa Falls, Georgia
Kelly Barnes Dam failed, killing 39 students and college staff and causing about $2.5 million in damages.
In response to these tragedies, President Jimmy Carter implemented the “Phase I Inspection Program” that directed the US Army Corps of Engineers to inspect the nation’s non-federal high-hazard dams. The findings of the inspection program, which lasted from 1978-1981, were responsible for the establishment of dam safety programs in most states, and, ultimately, the creation of the National Dam Safety Program, which today supports dam safety programs in 49 states. Alabama is the only state in the nation that has yet to pass dam safety legislation, although Alabama State Representative Mary Sue McClurkin introduced a bill on March 18, 2014 which, if passed, would establish a state dam safety program.
Emergency Action Plans
One of the key components of a successful dam safety program for high hazard and significant hazard dams is a comprehensive, up-to-date Emergency Action Plan (EAP). Hazard level does not reflect the condition or age of the dam; rather, it indicates the potential for loss in the event of dam failure. According to FEMA, the classifications are as follows:
High hazard: Facilities where failure will probably cause loss of human life. Such facilities are generally located in populated areas or where dwellings are found in the flood plain and failure can reasonably be expected to cause loss of life; serious damage to homes, industrial and commercial buildings; and damage to important utilities, highways, or railroads.
Significant hazard: Facilities where failure would likely not result in loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. Such facilities are generally located in predominantly rural areas, but could be in populated areas with significant infrastructure and where failure could damage isolated homes, main highways, and minor railroads or disrupt the use of service of public utilities.
Low hazard: Facilities where failure would result in no probable loss of human life and low economic and/or environmental losses. Such facilities are usually located in rural or agricultural areas where losses are limited principally to the owner’s property or where failure would cause only slight damage to farm buildings, forest and agricultural land, and minor roads.
Unfortunately, about 22% of high hazard dams and 40% of significant hazard dams nationwide still do not have EAPs, meaning that thousands of dams across the United States lack EAPs required by law. And dams are still failing. According to the Association of State Dam Safety Officials, 173 dams across the United States have experienced failures since 2005.
The lack of an EAP could be problematic in the event of dam failure, said Mark Ogden, project manager for the Association of State Dam Safety Officials, who also noted that while such worst-case scenarios are rare, they have happened. “An exercised, well-prepared emergency action plan is a valuable tool to help save lives,” Ogden said.
Ogden also noted that even when dams have an EAP, downstream residents often do not know where to find it. “There have been a lot of efforts in recent years to try to make the public aware of dams and the potential dangers, and to know if they live in an area downstream of a dam, the failure inundation zone, who to talk to – whether it’s the dam owner or more likely the local emergency management officials – to find out if there is an EAP for that dam and what they would need to do,” Ogden said.
The good news is that most states have responded to the need for dam safety regulations and require EAPs for high hazard and significant hazard dams. The most recent legislation came in February of this year, when the State of Connecticut Department of Energy and Environmental Protection (DEEP) adopted new regulations concerning the preparation and update of EAPs for Class C and Class B dams. In 2013, fewer than 60% of regulated high hazard dams in Connecticut had an EAP, a statistic the State is hoping to drastically improve. The new EAP regulations include criteria for inundation mapping, dam monitoring procedures, formal warning notification and communication procedures, emergency termination protocols, and EAP review and revisions.
Currently, the only states without EAP requirements are Georgia, Illinois, Iowa, Kentucky, North Carolina, Vermont, Wyoming, and — ironically enough — California. Since Alabama still has no formal dam safety program, they also do not require EAPs.
ASDSO continues to work alongside the American Society of Civil Engineers (ASCE), American Council of Engineering Companies (ACEC), and other stakeholders to promote dam safety and to encourage legislation to protect the public and the environment from disasters such as the Ka Loko Dam failure in Kauai, Hawaii.
“The tenth anniversary of the dam’s failure reminds us of the potential dangers posed by dams and the critical importance of both responsible dam ownership and strong dam safety programs,” said Lori Spragens, executive director of the Association of State Dam Safety Officials (ASDSO). “Most dam failures are preventable disasters. Dam owners must keep their dams in the state of repair required by prudence, due regard for life and property, and the application of sound engineering principles. The quality of dam maintenance, emergency planning, and enforcement programs directly affects the safety of communities, as sadly demonstrated on Kauai. With more than 87,000 dams of regulatory size in the U.S., we all have a stake in dam safety.”
In general terms, a dam is any structure that obstructs or converts the flow of water in rivers and streams, and they frequently serve more than one purpose. Dams store water to compensate for fluctuations in river flow, and they also provide irrigation, hydropower, drinking water, flood control, and support for recreational activities. There are four main types of dams, and dams are often a combination of these different types:
Embankment Embankment dams are typically constructed from natural earth materials such as rock and compacted soil, and are therefore far less expensive than concrete dams. Therefore, not surprisingly, more than 80% of all large dams in the United States are embankment dams. Typically used to retain water across wide rivers, embankment dams have a triangular profile and an impervious core and are termed “earthfill” or “rockfill” depending on whether they are primarily comprised of earth or rock.
Gravity Gravity dams are constructed of concrete or stone masonry and span narrow river valleys with firm bedrock. They are designed to hold back water by simply using the weight of the dam alone to resist the horizontal water load pushing against it. Each section of the gravity dam is stable on its own, independent of any other dam section.
Arch While arch dams are also constructed of concrete, they differ from gravity dams in that they are designed to transfer water loads to adjacent rock formations. Arch dams are constructed only in narrow canyons with strong rock walls that are able to resist the arch pressure at the foundation and sides of the dam. Arch dams are thin and require less material than any other type of dam.
Buttress Buttress dams are hollow gravity dams with a solid upstream side that is supported by a series of buttresses on the downstream side. Constructed of reinforced concrete, buttress dam walls are straight or curved and are extremely heavy, pushing the dam into the ground.
Dams in the U.S.
In the United States, there are approximately 84,000 dams. The average age of these dams is 52 years old, and by 2020, over 70% of our nation’s dams will be over 50 years old, which is the widely-accepted longevity of most dams. In addition, the number of high-hazard dams, which are dams whose failure would likely cause the loss of life, is on the rise. Currently there are over 14,000 high-hazard dams nationwide, with another 13,000 being labeled significant-hazard, meaning their failure would cause significant economic loss. There are over 4,000 deficient dams, meaning they are at serious risk of failure, and 2,000 of these deficient dams are also high-hazard. The cost to repair these dangerous dams is estimated to be about $21 billion.
Many of our dams were originally constructed as low-hazard dams, which have more lenient design criteria due to their location in non-developed areas, typically agricultural. However, with the nation’s population growth and extensive development, these dams are now located in populated areas and considered high-hazard. This trend is expected to continue as population steadily increases.
The federal government owns only 3,225 — about 4% — of our nation’s dams. The remaining dams, over two-thirds of which are privately owned, fall under the jurisdiction of state dam inspection programs, with no federal oversight or regulation. State dam safety programs provide the permitting, inspection, and recommendations, along with enforcement authority, for 80% of our nation’s dams. Only one state, Alabama, completely lacks a dam safety regulatory program, but the rest are sorely underfunded and understaffed. For example, the average number of dams per dam safety inspector is 207. It is indeed daunting that dam safety programs are largely responsible for public safety, yet lack the resources to effectively provide that safety.
What causes dam failure?
Overtopping causes 34% of all dam failures. Inadequate spillway design, blocked spillways, settlement of the dam crest, and floods exceeding dam capacity are all causes of overtopping.
Foundation defects such as slope instability and settlement cause about 30% of all dam failures.
Piping, resulting in internal erosion caused by seepage, causes 20% of all U.S. dam failures.
The remaining 16% of dam failures are the result of other causes including structural failure of materials, inadequate maintenance, settlement and cracking, and deliberate acts of sabotage.
What can we do?
The 2010 Iowa Lake Delhi dam failure cost our economy about $170 million between damages and economic losses, and the 2006 Kaloko Reservoir Dam failure in Hawaii killed seven people. To make matters worse, the Kaloko dam was over 100 years old and had never once been inspected prior to its failure. Our dams have been given a “D” rating from the American Society of Civil Engineers (ASCE) 2013 Infrastructure Report Card, and the ASCE has recommended steps to take to improve that rating, one of which is the development of Emergency Action Plans (EAPs) for 100% of our nation’s high-hazard dams by 2017. Only 66% currently have EAPs.
Having effective EAPs at all high-hazard, and most significant-hazard, dams in the United States is the most important step in reducing the risk for loss of life and property damage from dam failures, and it is absolutely critical that deficient high-hazard dams have updated EAPs in place. To that end, Tata & Howard has been working with the Connecticut Department of Energy and Environmental Protection (CT DEEP) this spring to perform over 40 dam inspections and update over 30 EAPs.
Besides maintaining EAPs for high-hazard dams, ASCE recommends the following steps to address our nation’s dam infrastructure:
Reauthorize and fully fund the National Dam Safety Program (NDSP), which is a partnership of the states, federal agencies, and other stakeholders that encourages individual and community responsibility for dam safety.
Establish a national dam rehabilitation and repair funding program to cost share repairs to publicly owned, nonfederal, high-hazard dams.
Implement a national public awareness campaign to educate individuals on the location and condition of dams in their area.
Encourage incentives to governors and state legislatures to provide sufficient resources and regulatory authorities to their dam safety programs.
Require federal agencies that own, operate, or regulate dams to meet the standards of Federal Guidelines for Dam Safety.
In addition to local and federal oversight and regulation, there are a number of steps that the public can take to minimize the risks associated with dam failure:
Know your risk. Find out if you live in a dam breach inundation zone by contacting your local emergency management agency or by contacting your state dam safety program (www.damsafety.org).
Know your role. Know the dams in your area where you live and work, and be aware of potential maintenance issues and report them to authorities immediately. Dam owners have the responsibility to maintain their dams and to have an EAP, especially for high-hazard dams, and should work with the federal or state regulator to comply with safety standards.
Take action. Inform your friends and neighbors about the benefits and risks associated with dams and have an evacuation route in place for your family and/or business should a dam fail. If you live below a dam, it is imperative that you maintain flood insurance.
Dams are an integral part of our infrastructure, providing many important benefits. A large percentage of our nation’s dams are in need of repair and updating, and our high-hazard dams are of particular concern. It is critical that all of us, including the federal government, states, communities, engineers, and private dam owners, work together to promote dam safety and education. Our future depends on it.