Dams are innately hazardous structures. Failure or mis-operation can result in a catastrophic release of water causing negative impacts upstream or downstream. Negative impacts of primary concern are the loss of human life, economic loss including property damage, lifeline disruption and environmental damage.

Some dams are considered to have a greater hazard potential than others. As of 2021, there are approximately 16,500 high-hazard potential dams in the United States. Jennings Randolph Lake's Risk Assessment is categorized as "High".  "High-hazard potential" is a term used by a majority of state dam safety programs and federal agencies as part of a three-pronged classification system used to determine how hazardous a dam's failure might be to the downstream area.

While the definition varies from place to place, it generally means if failure of a high-hazard dam occurs, there probably will be loss of life. It must be emphasized that this determination does not mean that these dams are in need of repair - these dams could be in excellent condition or they could be in poor condition.  High hazard just reflects the dam's potential for doing damage downstream should it ever fail.

Dam failures or partial failures are not usually caused by storm events. Most failures fall into one or more of the following categories:

Structural failures: Foundation defects, including settlement and slope instability, or damage caused by earthquakes, have caused about 30 percent of all dam failures in the United States.

Mechanical failures: Malfunctioning gates, conduits, or valves can cause dam failure or flooding both upstream and downstream and account for about 36 percent of all dam failures in the United States.

Hydraulic failures: Overtopping of a dam is often a precursor to dam failure. National statistics show that overtopping due to inadequate spillway design, debris blockage of spillways, or settlement of the dam crest accounts for approximately 34 percent of all dam failures in the country.

These problems can lead to dam failure:

• Inadequate design criteria

• Malfunction of dam components

• Spillway damage or malfunction

• Seepage problems

• Embankment stability problems

• Damage from vandalism

• Improper operation

Common practice among federal and state dam safety offices is to classify a dam according to the potential impact a dam failure (breach) or mis-operation (unscheduled release) would have on upstream and/or downstream areas or at locations remote from the dam. The existing classification systems are numerous and vary within and between both the federal and state sectors. Although differences in classification systems exist, they share a common thread: each system attempts to classify dams according to the potential impacts from a dam failure or mis-operation, should it occur. The most significant problem with these various systems is the use of terms that lack clear definition. In addition, the various systems use different terminology to define similar concepts. This precludes consistency between the various federal and state agencies and understanding by the public.

Three classification levels are adopted as follows: LOW, SIGNIFICANT, and HIGH, listed in order of increasing adverse incremental consequences. The classification levels build on each other, i.e., the higher order classification levels add to the list of consequences for the lower classification levels. 

1. LOW HAZARD POTENTIAL
Dams assigned the low hazard potential classification are those where failure or misoperation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner’s property.

2. SIGNIFICANT HAZARD POTENTIAL
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be located in areas with population and significant infrastructure.

3. HIGH HAZARD POTENTIAL
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.

USACE has a robust Dam Safety Program that includes day-to-day inspections, as well as a more thorough annual inspection process. Large scale periodic inspections occur every five years. A multidisciplinary team led by a professional engineer, in conjunction with Baltimore District Operations personnel, performs periodic inspections at the project site. 

 JRL has installed a year-round early warning system at Jennings Randolph Lake intended to notify downstream public users of impending rapid increases in water levels, and to evacuate the river immediately to higher ground for their safety. The siren is triggered when increased releases need to be made from the dam, which will lead to flows or flow increases that are unsafe for recreation.  Read more about the early warning system here.

Federal Emergency Management Agency - National Dam Safety Program

United States Department of Homeland Security - Dams Sector

United States Army Corps of Engineers - National Inventory of Dams

American Society Of Civil Engineers - Report Card on Dams

The most important thing to remember is keep your distance, keep your life. Steer clear of dam structures by recreating further up- or downstream, or portaging your kayak or canoe around the dam. Stay in designated recreation areas.  Dams are not intended to be playgrounds, and pose many risks. Always be aware of your surroundings, know the location of dams, stay away from dams, and wear a personal floatation device such as a life jacket.

If you chose to take advantage of the recreation at JRL, make sure you follow these tips: 

1. Know the area: Check maps or speak with locals to get information about hazards on that waterway. If swimming or fishing, always remain a safe distance from the structure to avoid sudden currents. If kayaking, canoeing, or boating, always portage around the structure or turn around well before reaching the dam to avoid being pulled over.
2. Read the signs: Obey any and all posted signage and barriers in the area, including flood warnings, restricted access signs, portage signs, or other posted signs.
3. Dress for danger: Wear a personal floatation device (such as a life jacket) if you are boating, fishing, swimming, or otherwise recreating in or around a waterway.
4. Tell someone your plans: Let someone know, such as a friend or family member, when and to where you are heading out, and let them know when you return so they know you are safe.
5. If you see someone in trouble, do not enter: Never enter the water yourself to try and help someone. Instead, call 911 and use a remote assistive device, such as a rope or throw bag, to try and pull them back to safety.

Click to learn about 16 Common Safety Hazards including hazards from water flows, human activities, environmental factors, and dam structures. 

loodplain maps show the area expected to be inundated by floodwaters due to runoff from a rainfall event of a particular frequency from a riverine source. For example, Flood Insurance Rate Maps (FIRMs) published by the Federal Emergency Management Agency (FEMA) typically show the 1-percent-annual-chance (100-year) floodplain and sometimes a 0.2-percent-annual-chance (500-year) floodplain. The 1-percent-annual-chance floodplain is the area inundated by a flood having a 1-percent chance of being equaled or exceeded in a given year. FIRMs are utilized by communities who are participants in the National Flood Insurance Program to guide and regulate development. They are also utilized to determine flood insurance purchase requirements and rates.

Dam failure flood inundation maps show the estimated area expected to be flooded due to a failure or an uncontrolled release from a dam. These maps may consider different failure scenarios such as a non-rainfall-induced failure, also known as a sunny day or fair weather failure, or failure during a rainfall event. Dam failure flood inundation areas can be much larger than the 1-percent-annual-chance floodplain. The flood is more like a wave than a steady current and can have great power and force. Dam failure flood inundation maps are utilized by engineers and emergency managers to determine warning and evacuation areas downstream of a dam. It is important to note that dam failure flood inundation maps do not reflect the safety or integrity of a dam. Dams that meet safety regulations and are operated and maintained well may still have a dam failure flood inundation map.

USACE performs ongoing activities to ensure the integrity of Jennings Randolph Dam and to manage and reduce risk to downstream communities.  The dam is well maintained, inspected, and monitored. The frequency of inspection and monitoring increases during high water events.  USACE regularly updates the Emergency Action Plan for the dam and performs emergency response exercises with Federal, state, and local emergency managers to remain prepared to respond to flood events affecting the dam.  USACE also closely follows rainfall forecasts to determine when high water events may occur to provide information for any necessary flood warnings.