Monday, June 10, 2019

Episode 476 (6-10-19): Marking Dam Safety Awareness Day

Click to listen to episode (4:24).

Sections below are the following:
Transcript of Audio
Audio Notes and Acknowledgments
Extra Information
Related Water Radio Episodes
For Virginia Teachers (Relevant SOLs, etc.).

Unless otherwise noted, all Web addresses mentioned were functional as of 6-7-19. 


From the Cumberland Gap to the Atlantic Ocean, this is Virginia Water Radio for the week of June 10, 2019.

This week, we focus on a type of structure that’s found in over 2900 water locations in Virginia and that was the subject of a recent nationwide safety-awareness day.  Have a listen for about 15 seconds to three mystery sounds, and see if you can guess this kind of structure.

SOUNDS - ~15 sec

If you guessed dams, you’re right!  You heard water at the Little River dam and hydropower station near Radford, the Philpott Reservoir and hydropower dam on the Franklin County/Henry County border, and the dam creating the Virginia Tech Duck Pond in Blacksburg.  Since colonial times in the United States, dams have been built on small streams and large rivers for many purposes, including operating grist mills; supplying various kinds of industries; developing transportation canals; generating hydroelectric power; creating reservoirs for water supply, power-plant cooling water, flood control, or recreation; and making ponds for agriculture.  The sounds you heard are from three of Virginia’s over 2900 regulated dams, the majority of which are privately owned.  Virginia’s dams, in turn, are part of the over 90,000 dams nationwide, including about 20,000 unregulated dams, according to the 2018 inventory by the U.S. Army Corps of Engineers.  The Corps inventory states that the average age of the nation’s dams is 56 years.

Regulated dams are rated as presenting high, significant, or low human or economic hazard in the event of a failure; each classification requires a specified frequency of inspection.  Over 15,000 dams nationwide are rated as high hazard, and over 11,000 as significant hazard, according to the Association of State Dam Safety Officials.  Note that those ratings are of potential risk from a dam’s failure, not the structural integrity or condition of a dam.

Safety at the nation’s dams is the focus of National Dam Safety Awareness Day, held each May 31 and coordinated by the Dam Safety Officials Association.  It’s held in memory of the disastrous South Fork Dam failure in Johnstown, Pennsylvania, on May 31, 1881, the worst dam failure in the country’s history.  The purpose of the day is to encourage proper oversight of dams, including adequate investment in dam inspection and maintenance.

Virginia Governor Ralph Northam’s Dam Safety Awareness Day proclamation for 2019 states that “all owners, governmental officials, first responders, emergency management personnel, downstream residents, and citizens should be aware of the importance of dam safety and the need to properly maintain and operate dams.”  For more information on dam safety in the Commonwealth, visit the “Dam Safety and Floodplains” link at the Department of Conservation and Recreation’s Web site,


Virginia Water Radio is produced by the Virginia Water Resources Research Center, part of Virginia Tech’s College of Natural Resources and Environment.  For more Virginia water sounds, music, or information, visit us online at, or call the Water Center at (540) 231-5624.  Thanks to Stewart Scales for his banjo version of Cripple Creek to open and close this show.  In Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you health, wisdom, and good water.


The sounds heard in this episode were recorded on May 6, 2017, at the Little River dam near Radford on January 16, 2017, at the Philpott Dam and Hydroelectric Station near Bassett, Va.; and at the Virginia Tech Duck Pond dam in Blacksburg on March 22, 2016.

Click here if you’d like to hear the full version (1 min./11 sec.) of the “Cripple Creek” arrangement/performance by Stewart Scales that opens and closes this episode.  More information about Mr. Scales and the group New Standard, with which Mr. Scales plays, is available online at


Locations of dams in Virginia. Map from the U.S. Army Corps of Engineers, “National Inventory of Dams,” online at

Dam on the Little River near Radford, Va., May 6, 2017.

Philpott Dam on the Smith River near Bassett, Va., January 16, 2017.

Dam on Stroubles Creek at the Virginia Tech Duck Pond in Blacksburg, September 30, 2015.


Dams Subject to the Law

The following information on regulation of dams is quoted from the Virginia Department of Conservation and Recreation, “Dam Safety and Floodplains/Dams Subject to the Law,” online at

“All dams in Virginia are subject to the Dam Safety Act and Dam Safety Regulations unless specifically excluded. A dam is excluded if it [meets one or more of the following criteria]:
is less than six feet high;
has a maximum capacity less than 50 acre-feet and is less than 25 feet in height;
has a maximum capacity of less than 15 acre-feet and is more than 25 feet in height;
is operated primarily for agricultural purposes and has a maximum capacity of less than 100 acre-feet or is less than 25 feet in height (if the use or ownership changes, the dam may be subject to regulation);
is owned or licensed by the federal government;
is operated for mining purposes under 45.1-222 or 45.1-225.1 of the Code of Virginia;
is an obstruction in a canal used to raise or lower water levels.”

Dam Classification - What does it mean? Why does it change?

The following information is quoted from the Virginia Department of Conservation and Recreation, “Dam Safety and Floodplains/Dam Safety Classification,” online at

“Virginia impounding structure regulations specify that each dam be classified based on potential loss of human life or property damage if it were to fail. Classification is based on a determination of the effects that a dam failure would likely have on people and property in the downstream inundation zone. Hazard potential classifications descend in order from high to low, high having the greatest potential for adverse downstream impacts in event of failure. This classification is unrelated to the physical condition of the dam or the probability of its failure. The hazard potential classifications are:
High - dams that upon failure would cause probable loss of life or serious economic damage;
Significant - dams that upon failure might cause loss of life or appreciable economic damage;
Low - dams that upon failure would lead to no expected loss of life or significant economic damage. Special criteria: This classification includes dams that upon failure would cause economic damage only to property of the dam owner.

“Safety standards become increasingly more stringent as the potential for adverse impact increases. For example, a high hazard dam--that is, one whose failure would cause probable loss of human life--is required to meet higher standards than a dam whose failure would not be as likely to result in such severe adverse consequences. Classification, however, is not static. Downstream conditions, including land use, can and often do change. Although a dam itself may remain relatively stable, it is subject to reclassification if a change occurs in the downstream inundation zone. For example, if homes are built in the downstream inundation zone of a Low Hazard or Significant Hazard dam, the dam could be reclassified to High Hazard.

“A change in hazard classification can create a dilemma because if a dam is reclassified, it usually does not meet the higher standards of the new hazard classification. To meet the required higher standards, the owner of the dam is often required to make structural modifications. Any dam that does not meet more protective standards of a high hazard dam could become deficient in the future if land use in the downstream inundation zone changes.

“To avoid the need for some of these structural modifications, all affected parties--dam owner, engineer, downstream land owners, and local governments--need to work together. People should be aware of the impacts development downstream can have on the required standards of a dam. It is better and cheaper to address this potential problem beforehand rather than wait and deal with modifications later.”


Association of State Dam Safety Officials site, online at

Edwin S. Clay, III, and Patricia Bangs, “From Gristmill to Hydro Power: Virginia’s Dams,” Bacon’s Rebellion, 10/3/05, online at

Franklin News-Post, Demolition of old Power Dam in Rocky Mount begins, 8/31/16.

Alison Graham, Jordan's Point dam removed from Maury River in Lexington, Roanoke Times, 5/24/19.

Charles A. Grymes, “Lakes, Dams, and Reservoirs in Virginia,” undated, Virginia Places Web site, online at

U.S. Army Corps of Engineers, National Inventory of Dams (2018).

Virginia Department of Conservation and Recreation, “Dam Safety and Floodplains,” online at; “Dam Safety Program,” online at

Virginia Governor’s Office, “Dam Safety Awareness Day” Proclamation, 5/31/19, online at


All Water Radio episodes are listed by category at the Index link above (  See particularly the “Overall Importance of Water” and “History” subject categories.

Following is a link to an episode on removal in 2004 of the Embrey dam on the Rappahannock River:
Episode 71, 7-11-11 – “Rappahannock Running Free” by Bob Gramann.

Following is a link to an episode on the area around the Philpott Dam:
Episode 360, 3-20-17 – Who Were Smith and Philpott and What Do They Have to Do with Virginia Water?


The episode—the audio, extra information, or sources—may help with the following Virginia Standards of Learning (SOLs).

2010 Science SOLs

Grades K-6 Earth Patterns, Cycles, and Change Theme
3.9 – Water cycle, including sources of water, energy driving water cycle, water essential for living things, and water limitations and conservation.

Grades K-6 Earth Resources Theme
3.11 – sources of energy.
4.9 – Va. natural resources, including watersheds, water resources, and organisms.
6.9 – public policy decisions related to the environment (including resource management and conservation, land use decisions, hazard mitigation, cost/benefit assessments).

Grades K-6 Force, Motion, and Energy Theme
4.2 – characteristics and interactions of moving objects (including that moving objects have kinetic energy).
6.2 – energy sources, transformations, and uses.

Grades K-6 Living Systems Theme
6.7 – natural processes and human interactions that affect watershed systems; Va. watersheds, water bodies, and wetlands; health and safety issues; and water monitoring.

Life Science Course
LS.11 – relationships between ecosystem dynamics and human activity.

Physical Science Course
PS.6 – energy forms, transfer, and transformations.

Earth Science Course
ES.6 – renewable vs. non-renewable resources (including energy resources).
ES.8 – influences by geologic processes and the activities of humans on freshwater resources, including identification of groundwater and major watershed systems in Virginia.

Biology Course
BIO.8 – dynamic equilibria and interactions within populations, communities, and ecosystems; including nutrient cycling, succession, effects of natural events and human activities, and analysis of the flora, fauna, and microorganisms of Virginia ecosystems.

Physics Course
PH.6 – mass and energy, including potential and kinetic energy.
PH.7 – energy transfer, transformations, and capacity to do work.

2015 Social Studies SOLs

Grades K-3 Economics Theme
2.8 – natural, human, and capital resources.
3.8 – understanding of cultures and of how natural, human, and capital resources are used for goods and services.

Virginia Studies Course
VS.1 – impact of geographic features on people, places, and events in Virginia history.
VS.10 – knowledge of government, geography, and economics in present-day Virginia.

United States History to 1865 Course
USI.5 – factors that shaped colonial America and conditions in the colonies, including how people interacted with the environment to produce goods and service.

Civics and Economics Course
CE.6 – government at the national level.
CE.7 – government at the state level.
CE.10 – public policy at local, state, and national levels.

World Geography Course
WG.2 – how selected physical and ecological processes shape the Earth’s surface, including climate, weather, and how humans influence their environment and are influenced by it.
WG.4 – types and significance of natural, human, and capital resources.

Government Course
GOVT.7 – national government organization and powers.
GOVT.8 – state and local government organization and powers.
GOVT.9 – public policy process at local, state, and national levels.
GOVT.15 – role of government in Va. and U.S. economies, including examining environmental issues and property rights.

Virginia’s SOLs are available from the Virginia Department of Education, online at

Following are links to Water Radio episodes (various topics) designed especially for certain K-12 grade levels.
Episode 250, 1-26-15 – on boiling, for kindergarten through 3rd grade.
Episode 255, 3-2-15 – on density, for 5th and 6th grade.
Episode 282, 9-21-15 – on living vs. non-living, for kindergarten.
Episode 309, 3-28-16 – on temperature regulation in animals, for kindergarten through 12th grade.
Episode 333, 9-12-16 – on dissolved gases, especially dissolved oxygen in aquatic habitats, for 5th grade.
Episode 403, 1-15-18 – on freezing and ice, for kindergarten through 3rd grade.
Episode 404, 1-22-18 – on ice on ponds and lakes, for 4th through 8th grade.
Episode 406, 2-5-18 – on ice on rivers, for middle school.
Episode 407, 2-12-18 – on snow chemistry and physics, for high school.