926a1e11e20ebf9087a5d5933870a153.jpgOn May 31st, we join together to commemorate National Dam Safety Awareness Day. On this day, we remember the lessons learned from past dam failures, push for strong dam safety programs, encourage investment in America's critical infrastructure and rededicate ourselves to the effective public-private partnerships that work to keep America's dams safe, operational and resilient.

The issue of dam safety was not widely recognized until 1889 when the failure of South Fork Dam near Johnstown, Pennsylvania claimed more than 2,200 lives. As we observe the 131th anniversary of this tragedy on May 31, we encourage you to understand the importance of dam safety, the role various parties play, and current dam safety issues.

Photo: Wreckage after the flood in Johnstown, PA (via Library of Congress). 
For a technical look at this failure view the South Fork Dam case study on DamFailures.org.


Dam Basics

NID Map2.pngWater is one of our most precious resources; our lives depend on it. Throughout the history of humankind, people have built dams to maximize use of this vital resource.

There are more than 90,000 dams in the United States (See Map) and most states are home to hundreds, if not thousands of dams. They are an extremely important part of this nation's infrastructure equal in importance to bridges, roads, and airports. They can serve several functions at once, including water supply for domestic, agricultural, industrial, and community use; flood control; recreation; and clean, renewable energy through hydropower.

To learn more about dam basics, visit Dams 101 under the Awareness Center dropdown.


Living with Dams

Living with Dams: Know Your Risks, was prepared by ASDSO to help answer questions about dams: what purposes they serve, what risks are associated with dams and where you can get information about how to react if you are affected by one.


A second booklet, Living with Dams: Extreme Rainfall Events, explains the engineering principles involved with predicting extreme rainfall events and how these principles are used to design safe, functional and economical dams. It connects the concepts of rain to floods to dams to failure and the flooding impacts downstream.



Current Dam Safety Issues in the United States

It is important to understand that both safe operation and maintenance are key to avoiding disaster. Dam failures can and have occurred in the U.S. causing loss of life and severe economic and environmental damage.A9Rm8cbw4_1u7pzp9_btk.jpg

A recent example of a dam failure in the United States is the Spencer Dam Failure that occurred in northern Nebraska on March 14, 2019 during a major flood and ice run on the Niobrara River (Pictured Right). To learn more about this failure, we recommend reviewing the Spencer Dam Failure Investigation Report. Of course, this isn't the only failure that has occurred recently. ASDSO has more than 700 failures in its Dam Safety Incident Database from the last decade. 

Despite understanding the need for safe operation and maintenance, the dam safety community still faces many challenges. One challenge is the increase in high-hazard potential dams (those whose failure could cause loss of life.) As our population grows and development continues, the overall number of high-hazard potential dams increases as well, with the number climbing to more than 15,000 in 2018. The increase is in part due to "hazard creep". Hazard creep describes the growth of development (buildings, businesses, and people) moving closer to dams that were originally located in agricultural areas. See a video on hazard creep below.

Hazard Creep - Youtube.png

View all ASDSO YouTube videos

To learn more about the top issues facing the dam safety community and state performance information, visit State Performance and Current Issues under the Awareness Center dropdown.


Investing in Critical Infrastructure

Investment is needed to rehabilitate deficient dams and to improve the efficacy of policies and regulatory programs that oversee dam safety programs. Upgrade or rehabilitation is necessary due to deterioration, changing technical standards, and improved techniques, as well as better understanding of the area's precipitation conditions, increases in downstream populations, and changing land use. When a dam's hazard classification is changed to reflect an increased hazard potential, the dam may need to be upgraded to meet an increased need for safety. Many dam owners, especially private dam owners, find it difficult to finance rehabilitation projects.

Since 2004, an ASDSO task group has tracked dam rehabilitation cost as follows:

Funding needs,
non-federal dams
Funding needs,
non-federal HH dams
$34 billion
$10.1 billion
$51.46 billion
$16 billion ($8.7b public, $7.3b private)
$53.69 billion
$18.2 billion ($11.2b public, $7b private)
$60.7 billion
$18.71 billion
$65.89 billion
$20.42 Billion 

(See the 2019 Cost of Rehabilitation Report)


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Images - Examples of Low Head Dams
Images - Examples of Low Head Dams
Images - Examples of Low Head Dams
Images - Examples of Low Head Dams
Images - Examples of Low Head Dams
Images - Examples of Low Head Dams

Recreation Near Dams - Keep Your Distance, Keep Your Life.

Each year, dozens of lives are lost on America’s waterways at structures called low-head or “run-of-the-river” dams. Among the victims are boaters, kayakers, swimmers, anglers and emergency responders.

Low-head dams are characterized by their low height — usually with a 1-foot to 15-foot drop off — which allows water to flow over the top of the dam. Below the surface, the water falling over the dam creates highly aerated, circulating currents that trap people and objects underwater against the face of the dam. These forces are a practically inescapable trap for even the strongest, life-jacket-clad swimmer or often boats and kayaks as well. Due to this danger, these structures have earned the title of “the killer in our river” or “drowning machines.”

People are often unaware of these dangers, or they underestimate their risk of falling victim to them. Many drowning victims deliberately jump from or float over them without knowing the risks. Others suddenly encounter them, as low-head dams are notoriously difficult to spot from upstream. The victims of these dams also include many would-be rescuers and first responders, several of whom have lost their lives trying to save others caught in the hydraulic current. Regardless of the cause or intention, outings on waterways can end in tragedy.

The late Dr. Bruce Tschantz, professor emeritus of the University of Tennessee, documented 377 fatalities at low-head dams from 1960 to August 2016, with the majority — 91 percent — occurring from April through August during the summer recreation season. Swimming, boating and fishing account for most incidents at dams in the United States.

Visit ASDSO's Public Safety Around Dams page or watch the Be a Dam Champion video (shown below) to learn more.

Additional Resources

ASDSO Dam Safety Incident Database - The database provides basic information on dam safety incidents to ASDSO members, dam safety stakeholders, the media and the public. You can search for incident information based on a number of search fields including dam name, state, downstream hazard potential, date and incident driver. 

Dam Owner Academy: Dams 101 (Video) - 'Dams 101' is the first in a series of educational videos for dam owners from the Association of State Dam Safety Officials (ASDSO). This video focuses on types of dams and how they work. Although this video is part of the dam owner series, this video is suitable for anyone looking for an introduction to dams.

Damfailures.org - Presented within this website are links to individual case studies as well as lessons learned pages that summarize historical dam incidents and failures and the valuable information gleaned from them. Each page contains a background and description, photographs, videos, best practices, and other resources related to the case study or lessons learned being addressed.

ASDSO Awareness Center - This area of our website includes more information on dam basics, dam failures, current issues, and public safety around dams.


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For more information, contact ASDSO Communications Manager Katelyn Riley - [email protected]