|
Public Safety & Awareness
|
Keeping Safe Around Dams:
Tips for swimmers, boaters, fishermen, and anyone who goes near the water...
|
|
|
|
|
Common Beliefs about Dams |
|
FICTION |
FACT |
|
“The Army Corps of Engineers is responsible for most of the dams in the U.S.” |
State dam safety programs have oversight of most dams in the U.S.
State agencies regulate more than 80% of the nation’s dams.
|
|
“Dams are like roads. The government takes care of them.” |
Private dam owners are responsible for more than 65% of the nation’s dams, including maintenance and upgrades.
Many lack the financial resources necessary for adequate dam maintenance.
|
|
"There are only a few dams in my state." |
There are more than 85,000 dams in the U.S. Most states are home to hundreds – or thousands – of dams of regulatory criteria.
• Texas has the most dams – more than 7,000 – followed by Kansas (6,087), Missouri (5,099), Oklahoma (4,755), and Georgia (4,606).
• Mississippi, North Carolina, and Iowa each have more than 3,000 dams.
• Five states – Alabama, Montana, Nebraska, South Carolina, and South Dakota – each have more than 2,000 dams.
• More than 1,000 dams are in each of 15 additional states.
• Of all states, Delaware has the fewest number of dams, with 86.
|
|
“That dam has been here for years – it’s not going anywhere.” |
Advancing age makes dams more susceptible to failure.
The average age of dams in the U.S. is more than 51 years old. As dams age, deterioration increases and construction costs rise. Some common problems of older dams are:
• Deteriorating metal pipes and structural components—after 50 years, metal rusts and fails.
• Sediment-filled reservoirs—sediment displaces storage of floodwaters. Some sediment may have contaminants from chemicals in runoff from upstream areas.
• Subdivisions and businesses built upstream—roofs and concrete streets and sidewalks increase the volume of runoff to the dam.
|
Whether you realize it or not, the odds are that you live or work near a dam.
Living With Dams: Know Your Risks is a booklet and new website designed to help answer questions about dams: what purposes they serve, associated risks, guidance for those living near dams, and where to find further information.
The booklet provides a general overview of dams and dam safety, and answers the following questions:
(1) Why should I care about dams?
(2) What are the risks associated with dams?
(3) Could I be affected by a dam? What is the dam failure flood inundation area?
(4) Once I determine that my property is in a dambreak inundation area, what's next?
Public Safety Around Dams
|
This photo, taken by an Indiana dam inspector, demonstrates the need for warning signage around in-channel dams (not to mention extremely poor judgment by the adult fisherman). |
How NOT to Behave Around a Dam
1. Child fishing on bank next to log
2. Large caliber semi-automatic pistol on top of tackle box
3. Man fishing over an in-channel dam's hydraulic recirculation zone
|
|
Be Aware of Boating or Swimming Near Low Head Dams!
Under this raging waterfall is a "low head" or "run-of-the river" dam.
When water flows over these structures a deadly "roller effect" can form pulling everything under with very little chance for escape.
Imagine if this truck were a kayaker, boater or swimmer.
(Video by Chris Harrod, Anderson County Fire Department, Lawrenceburg, KY)
View news footage of this incident.
Additional incidents
|
|
"Hidden Dangers and Public Safety at Low-head Dams"
Paper by Bruce A. Tschantz, PE, PhD, and Kenneth R. Wright, PE, published in the Journal of Dam Safety, V.9 n.1, 2011.
Low-head dams, a.k.a. "killer dams" or "drowning machines," can trap victims in a submerged hydraulic jump formed just downstream from the dam. Hundreds of people have been killed at low-head dams, but few states regulate these dangerous structures because of their small heights of up to about 12 feet. A recent study reflects a sobering reality of the problem from a national hazard perspective. This paper explains the hydraulic action below low-head dams, examines structural and non-structural measures to reduce drownings, and presents a drowning case study that the authors have investigated. Full text.
The "Roller Effect"
|
|
Small dams are deceptively dangerous. They are often hard to see, especially from the upstream side. They don't look dangerous, so people often get too close and become trapped in the hydraulic roller. |
More Examples of the Dangers of Low-Head Dams:
Canoeist Speaks Out On Dangers Of Dams. KELO-TV, 7/14/11
Boater narrowly escaped drowning after going over a dam on South Dakota's Big Sioux River.
Second Franklin County drowning occurs at low head dam. The Roanoke Times, 7/24/09
Two drowning in two months occur at the same Virginia dam.
Dangerous Low Head Dams in Des Moines, Iowa. KCC News, 8/10/2007
Low-head dams are extremely dangerous although they do not appear so.
Additional incidents can be researched through the ASDSO Bibliography.
Resources:
American Whitewater Accident Database (Scroll down the page for the search menu.)
Brigham Young University Research Project - Fatal Submerged Hydraulic Jumps
Canadian Dam Association. Public Safety Around Dams. CDA Bulletin, Spring 2009.
Iowa DNR. Low Head Dams - Information for the Public
Iowa DNR. Solving Dam Problems - Iowa's 2010 Plan for Dam Mitigation
|
For additional resources, search the ASDSO Bibliography. |
Suggested keywords:
accidents, low-head dams, public awareness, public safety |