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Federal Guidelines for Dam Safety Risk Management 

I. Background 

Agencies, owners, and regulators have been using risk to inform decisions within various industries 

across the world for quite some time. In particular, the United States, the United Kingdom, the 

Netherlands, and Australia have integrated risk into safety decisions in various ways since the 

1950’s. Those entities that analyze, evaluate, and manage risks have found that risk provides a 

rigorous, systematic, and thorough process that improves the quality of and support for safety 

decisions. Several entities in the dam safety industry have been using risk to inform decision since 

the late 1980’s. Notably, the Australian Committee on Large Dams, BC Hydro, and the Bureau of 

Reclamation adopted risk management strategies to assess and manage risks for their dams. For 

entities that own or regulate dams, various decisions are made with respect to an individual 

structure or for a portfolio of structures: 

 Decisions regarding the safety of a structure 

 Decisions regarding actions to reduce risks 

 Decisions related to prioritizing actions within a portfolio of structures 

Using risk to inform decisions involves three distinct components. These components, each having 

their own purpose and function, are: 

 Risk Analysis 

 Risk Assessment 

 Risk Management 

Figure 1 shows how risk management, risk assessment, and risk analysis relate to each other. Dam 

Safety Risk Management includes routine and non-routine activities and is the umbrella under 

which risk is used to inform decisions by owners and regulators. Risk communication, although not 

specifically identified in Figure 1,is a critical part of each component of risk management. 

The term risk when used in the context of dam safety is comprised of three parts – (1) the likelihood 

of occurrence of a load (e.g. flood, earthquake, etc.), (2) the likelihood of an adverse structural 

response (e.g. dam failure, damaging spillway discharge, etc.), and (3) the magnitude of the 

consequences resulting from that adverse event (life loss, economic damages, environmental 

damages, etc.).Figure 2 depicts the flow of recurring dam safety activities and how risk information 

is used to inform decisions on dam safety actions and setting priorities. 

A. Risk Analysis 

Risk analysis is the first component of risk management. It is the portion of the process in 

which the potential failure modes, structural performance, and adverse consequences such as 

large operational discharges are identified and for which a quantitative or qualitative 

estimate of the likelihood of occurrence and magnitude of consequence of these potential 

events are made. A critical first step of a risk analysis is the identification of the specific 
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potential failure modes that are most likely at a given dam. The frequency of occurrence of 

the loadings (reservoir load levels, floods, earthquakes, ice loading, etc.) that could initiate 

potential failure that might cause adverse consequences are estimated and considered as part 

of a risk analysis. 

Figure 1 - Relationship between Risk Analysis, Risk Assessment and Risk Management 
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Figure 2 – Recurring dam safety activities
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B. Risk Assessment 

Risk assessment is the process of examining the safety of a specific structure, making 

specific recommendations, and recommending decisions on a given dam or project using 

risk analysis, risk estimates, and other information that have the potential to influence the 

decision. The risks are assessed by the dam owner and – if applicable – the regulator, 

owner’s engineer, or other stakeholders. The assessment considers all factors (likelihood, 

consequences, cost, environmental impacts, etc.) and may also use evaluation criteria 

established by the owner or regulator. Decisions may include additional or enhanced 

monitoring, additional investigations and/or studies/evaluations/analyses, remedial actions 

or abandonment of the dam, or no additional actions. 

C. Risk Management 

Risk management encompasses activities related to making risk-informed decisions, 

prioritizing evaluations of risk, prioritizing risk reduction activities, and making program 

decisions associated with managing a portfolio of facilities. Risk management includes 

evaluating the environmental, social, cultural, ethical, political, and legal considerations 

during all parts of the process. These include potential structural and non-structural actions 

on a given dam or project, but also include such activities as routine and special inspections, 

instrumented monitoring and its evaluation, structural analyses, site investigations, 

development and testing of emergency action plans and many other activities. 

D. Risk Communication 

 Risk communication is a critical component of an effective risk informed decision process. 

It is not identified as a separate component of the process but rather it is something that must 

be integrated into all aspects of the process. Risk communication is essential within an 

owner/regulator organization but also with other individuals/organizations who have a stake 

in the dam or would be impacted by its failure. 

II. Objectives of the Guideline 

Federal Agencies seek to ensure the structural integrity and operational safety of the dams in their 

charge and in so doing wisely allocate the use of monetary and human resources. 

Federal agencies consider in the exercise of their Dam Safety responsibilities, that: 

 There are certain principles that should be held in common for consistency and correctness; 

 There should be a common understanding of risk management processes; 

 There are commonly recognized standards for safety and tolerable risk, and; 

 There are technical tools and approaches related to risk analysis that can be mutually shared 

and jointly developed. 

Risk Analysis and Risk Assessment provide fundamental input to risk-informed decisions and to the 

extent that is reasonable and practicable, the tools, procedures, and guidelines should be consistent 

among the agencies. 
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This guideline will provide the means by which Federal agencies will use the general principles of 

risk management and using risk to inform decisions. The agencies will work to develop and 

maintain consistent application of Risk Analysis, Risk Assessment, Risk Management and Risk 

Communication using equivalent procedures and tools. 

The guidance offered and the specific procedures identified in this guideline are not mandated and 

the agency may vary in the application of these guidelines as necessary to accomplish their 

respective missions. Definitions of selected terms related to risk informed decision process are 

provided in Appendix A for consistency in the use and implementation of this guideline. 

III. Risk Analysis 

A. Risk Analysis / Risk Estimation

Risk analysis is typically a quantitative process (i.e. the outputs and inputs to a risk 

assessment are numeric). However, risk may also be expressed qualitatively. Risk analyses 

can provide valuable input to decisions made at various stages of a project or for varying 

purposes. They can include decisions made for a single dam or within a portfolio of dams. 

Thus, several types of risk analyses can be used as described below. The first step common 

to all types of risk analyses is the identification of the site-specific potential failure modes. 

Risks are typically quantitatively evaluated by failure mode. The failure modes are then 

rolled up within a decision framework at a particular structure. For a given dam or project, 

all the relevant types of loadings that may be experienced should be considered when 

identifying potential failure modes. 

Methods to calculate and estimate risks are constantly evolving. This document does not try 

to describe in detail how to analyze risks, it only describes the general practices used by 

The following principles apply to the overall objectives of this guideline: 

1. Life safety is paramount. 

2. Risk should inform decision process and improve the state of safety related to dams. 

3. Identify and reduce the risk to life and property posed by dams and reduce those risks to 

as low as reasonably practicable. 

4. Each agency has a unique authority, mission, and management practice. Their use of 

risk to inform decisions may vary. 

5. . 

6. The urgency of completing dam safety actions should be commensurate with the level 

of risk. 
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those who analyze risks. The current state-of-the-practice for analyzing risks is the Best 

Practices in Dam Safety Risk Analysis, which is a document and accompanying training 

course developed by the Bureau of Reclamation and the Corps of Engineers. 

B. Types of Risk Analysis

There are various types of risk analysis. The level of information and the uncertainty 

reflected in the risk estimates will vary. Generally, more detailed risk analyses (those 

associated with Issue Evaluations and Risk Reduction) have more detailed analyses 

available and studies have been performed to try to reduce the amount of uncertainty. More 

detailed risk analyses will generally be led by an experienced facilitator and be done by a 

qualified multi-disciplinary team. 

Potential Failure Modes Analysis 

A potential failure modes analysis is a critical first step in conducting a risk analysis. It 

requires a detailed records review and a review of dam performance (instrumentation, 

visual, operational). Some information is also needed on flood and earthquake frequencies 

in order to consider hydrologic and seismic potential failure modes. The perspective of local 

office personnel, including dam operators, inspectors, and dam tenders is invaluable. The 

goal of a potential failure modes analysis is to identify the site-specific credible potential 

failure modes for a given dam and provide complete descriptions of the potential failure 

modes, including the initiating event, the progression steps leading to an uncontrolled 

release of the reservoir, a general description of the magnitude of the breach including 

identification and recording of the factors that make the potential failure more likely and 

those that make it less likely. Similarly, factors that make the consequences more or less 

severe are identified and documented. 

Screening Level Risk Analysis 

A screening level risk analysis is typically performed for a portfolio of dams. The goal is to 

identify potential failure modes and develop relative risk estimates for each dam such that 

the relative risk among the dams can be evaluated and priorities for further study or 

remediation can be established. Information on loadings, consequences and analyses that 

relate to potential failure modes may be very basic and limited and typically consist of what 

was already available or prepared just in advance of the screening effort. Screening level 

risk analyses have typically had very mixed results in terms of identifying key dam safety 

issues. A screening level risk analysis can be a valuable tool for identifying uncertainties 

related to potential failure modes and significant dam safety issues. They can be used to 

prioritize additional studies and initiate modification studies at dams. Screening level risk 

analyses can either be made quantitatively or qualitatively. 

Periodic Risk Analysis 

A periodic inspection of all dams is required under the Federal Guidelines for Dam Safety1

. 

A comprehensive, periodic dam safety review that documents the condition of the dam at a 

point in time should incorporate a risk analysis to enhance the value of the effort. 

Additional analyses and studies are typically not performed specifically for a periodic risk 

analysis as the analysis relies on existing information. The risk analysis for a periodic dam 

safety review can be performed by an individual, but there are distinct advantages to 

 

1

 Federal Guidelines for Dam Safety. Federal Emergency Management Agency. September 2005. 
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engaging a small team. A periodic risk analysis focuses on all potential failure modes that 

are considered credible at the dam. Periodic dam safety reviews of dams are performed on a 

recurring cycle, with the interval between assessments determined by the agency. 

Issue Evaluation Risk Analysis 

Issue evaluation risk analyses are typically facilitator-led team risk analyses and are focused 

on a specific potential failure mode (or perhaps more than one potential failure mode) that 

may require additional engineering analyses, studies, or investigations to support a 

quantitative risk analysis. These supporting activities are completed to reduce uncertainty 

and increase confidence in the resulting risk estimates. Typically field explorations, 

material testing programs, detailed studies and analyses or a combination of these will be 

performed to provide information for the risk analysis. Analyses and studies may focus on 

loadings, structural response, consequences, or a combination of these. Issue evaluation risk 

analyses are usually conducted with an experienced risk analysis facilitator and a team with 

experience and backgrounds that match with the potential failure mode or modes being 

evaluated. 

Risk Reduction Analysis 

A risk reduction analysis is used to estimate the anticipated risk for critical potential failure 

modes after potential dam modifications or or non-structural measures are implemented. 

Risk Reduction Analyses of the proposed alternative remediation measures are necessary to 

verify that planned remediation measures will achieve the desired risk reduction result. 

They are used when evaluating risk reduction alternatives and should be one of the factors 

considered when selecting a preferred alternative. They typically involve reviewing risk 

estimates from an existing risk analysis, deciding which events will be impacted by the 

changes and re-estimating the likelihood of those events. 

C. Quantitative versus Qualitative Risk Analyses 

Each type of risk analysis can be accomplished using either a quantitative or qualitative 

approach. In both of these approaches a comprehensive identification, written description, 

discussion and evaluation of factors that make events more or less likely to occur for each 

credible potential failure mode is documented. The magnitude of consequences related to a 

potential failure is also characterized (quantified), discussed, and documented. 

D. Risk Analysis Results

Risk analysis results are typically portrayed with plots that graphically portray the risk 

estimates (likelihood of failure vs. economic loss and potential life loss) with an 

accompanying table that provides the input data used to generate the graphs. Two types of 

graphs are typically used. The first plots individual failure modes that portrays the potential 

for life loss as the estimated number of lives that would be lost (N) on the x axis and the 

annualized probability of the failure (f) associated with the life loss on the y axis and is 

referred to as an f –N plot. An f-N plot depicts both societal and individual risk. In addition 

to risk estimates for individual potential failure modes, the total risk for the facility is 

plotted. The second plots the cumulative risk posed by all failure modes and the associated 

potential life loss and is commonly referred to as an F-N plot. An F-N plot depicts societal 

risk. Both f-N and F-N plots require quantitative risk estimates. Figures 3 thru 6 are 

examples of f-N and F-N plots. For qualitative risk estimates, the results can be plotted 

using a matrix (see Error! Reference source not found.). Figures 8 and 9 provide 
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examples of an f-n and F-n plot with data added. Figure 9 depicts cumulative risk as well as 

risk for individual potential failure modes. 

Figure 32 - Bureau of Reclamation f-N Plot Figure 43 - U.S. Army Corps of Engineers Societal 

Risk Plot

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1 10 100 1,000 10,000

f, Estimated Annual Failure Probability

N, Estimated Life Loss

Decreasing justification 

to reduce or better 

understand risks

Evaluate Risks Thoroughly, 

Ensuring ALARP Considerations 

are Addressed

Increasing justification 

to reduce or better 

understand risks

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1 10 100 1,000 10,000

F, probability per year of potential loss of life ≥ N

N, Number of Fatalities

Risks are unacceptable,

except in exceptional

circumstances

Risks are tolerable

only if they satisfy

ALARP requirements

Societal Tolerable Risk Limit

Risks may be 

unacceptable or 

tolerable,

but will be 

examined 

thoroughly and 

must at a 

minimum satisfy 

ALARP 

requirements
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Figure 54 - Australian National Committee on 

Large Dams Societal Risk Plot

Figure 6 - New South Wales Dam Safety 

Committee Societal Risk Plot

Figure 75 - Qualitative Risk Matrix 

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0 1 10 100 1,000 10,000

F, probability of failure per dam per year with expected loss of life >=N

N, number of fatalities due to dam failure

Revised ANCOLD Societal Risk Reference Guideline

Risks are Tolerable

only if they satisfy

the ALARP

requirements

Risks are unacceptable,

except in exceptional

circumstances

limit of tolerability

for existing dams

limit of tolerability

for new dams or 

major augmentations

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0 1 10 100 1,000 10,000

F,probability of failure per dam per year with an expected loss of life >=N

N, number of fatalities due to dam failure

Proposed Societal Risk Requirements: Existing Dams

Full SBA

Required

as a

minimum -

Full 

DSC decision

based

on critical

review of

benefits and

risks

Risks are Intolerable

Risks are Negligible

limit of tolerability

for existing dams
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Figure 8 – An f-N plot showing individual potential failure mode and total risk. 

Figure 9 – An F-N plot showing cumulative risk with individual potential failure mode risks added.
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1. Preparing the Dam Safety Case 

Numerical risk estimates are based on judgments, are typically subjective, and 

include varying degrees of uncertainty. These estimates should not be the sole basis 

to inform decisions. Understanding the basis of the risk estimates is as important as 

the risk numbers themselves. The dam safety case is a logical and balanced ?? set of 

arguments used to advocate a position that either additional safety-related action is 

justified, or that no additional safety-related action is justified. The arguments string 

together key evidence regarding the three basic risk components, (load probability, 

response likelihood, and consequences) so as to support decisions related to a dam's 

existing condition is or ability to withstand future loading. The Dam Safety Case 

should be initially developed in the risk analysis phase and completed as part of the 

risk assessment for a given dam. 

. 

IV. Risk Assessment 

A. Risk Assessment / Risk Evaluation Process

Risk Assessment is the process of considering the quantitative or qualitative estimate of risk 

of the existing dam or project along with all other factors related to a safety decision such as 

the dam safety case, social / economic impacts, environmental impacts, constructability and 

potential to do harm. The risk assessment is made to determine a recommended course of 

action (which may involve considering a range of options) with regard to mitigating or 

accepting the risks related to a specific dam or project or with regard to a specific dam safety 

issue or operational concern on that project. 

The assessment and the decision is typically made by a technically qualified and 

experienced team (rather than a single individual) that can discern the relative criticality, the 

measure of concern and the type and degree of remedial action needed to address the issue. 

The most obvious and direct factors that enter into the assessment are the results of a risk 

The following principles apply to risk analysis: 

7. The basis for a coherent risk analysis should be a thorough examination and description 

of potential failure modes analysis. 

8. It should be recognized that each dam is unique in terms of purpose, geologic and 

demographic setting, design, structure, operations and conequences 

9. A well constructed dam safety case should include a discussion that supports and 

supplements the numerical risk estimates. 
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analysis. These results may come in the form of quantitative / numeric results or in the 

form of qualitative statements that indicate the measure of concern relative to public safety. 

Quantitative results provide three measures related to risk. They are: 

 Likelihood of occurrence of a failure or adverse consequence in terms of annual 

probability. 

 Estimated population at risk and/or life loss given failure or adverse consequence 

presented as the total estimated loss for a given annual probability of failure (often 

plotted or graphed) or the product of those two values which is called the “annualized 

life loss”. 

 The economic damages (downstream damages, cost to rebuild facilities, loss of 

operational revenue, regional social /economic damages, environmental damages, etc.). 

Again these can be given or plotted as the lost economic value versus the annual 

probability of occurrence or as an annualized cost. 

However, there are many other factors that should be included in Dam Safety Case and are 

considered in the decision recommendation, these include: 

 The risk analysis input for the dam safety case. 

 environmental considerations 

 public perception and public input 

 regional social and economic considerations 

 ease, difficulty and practicality of remediation 

 potential to do harm as the result of carrying out remediation 

 uncertainty in the results and in the remediation success 

This document focuses on a risk informed approach to make decisions. This method has the 

advantage of providing a more consistent basis for decision making. And since it is riskinformed rather than risk-based, it allows for other important factors to be considered in 

decision making, beyond a sole reliance on numerical risk estimates. 

B. The Dam Safety Case 

The risk estimates and the recommended actions need to be coherent. Since uncertainty is 

inherent in each assertion, the arguments should also address whether confidence is high 

enough for the assertions to stand on the basis of existing evidence. 

The dam safety case and the identification of risk management options are recognized as 

essential elements to ensure public protection. They represent the understanding of existing 

conditions and predicted future behavior stated as objectively as possible 
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C. Approach to Making Risk Informed Decisions

The concept and practice of the use of risk to inform dam safety risk assessment decisions 

evolved primarily from the recognition of and the desire to address the great deviation in the 

magnitude of potential life loss and to a lesser degree great variation in economic impact of 

potential failure of dams classified as high hazard. When Dam Safety became a strong force 

in the late 70’s, decisions were primarily based on the standard hazard classification of the 

dam (high, significant or low). Thus, a dam which had an estimated potential life loss of 

more than 1 person given dam failure was classified and treated the same as one which may 

have a potential life loss of several thousand. This lack of discrimination between the levels 

of consequences among high hazard dams led to proposals of criteria that would take the 

magnitude of loss into consideration. Among others, ANCOLD2

, British Columbia Hydro, 

the Netherlands, and the Bureau of Reclamation3

 proposed or developed evaluation criteria 

or guidelines. 

The above discussion presumes that a quantitative risk analysis is to be carried out. 

However, it may be noted that evaluation criteria could also be readily established, 

converted, or mapped for a qualitative risk analysis. 

D. Tolerable Risk 

Inherent in the use of risk analysis and risk informed criteria or guidelines and specifically in 

risk assessment is the recognition and understanding of tolerable risk. 

When risk assessment teams make decisions such as: (1) remediation for a project or dam 

will not be required – but that monitoring of the concern will continue, or (2) that a 

significant non–structural action will not be required or (3) that an alternative that addresses 

the major portion of the concern but does not deal with all aspects will be the course of 

action, then the risk remaining, related to that issue, is considered a tolerable risk. It can 

also be thought of considered or called the residual risk. It is the risk that remains after 

prudent actions to address the risk have been taken or the remote risk associated with a 

condition that was judged to not be a credible dam safety issue. 

Another way of describing or thinking about tolerable risk, is that after hearing all the facts 

and information related to an issue or issues on a dam or project, an organization decides 

that further action is not reasonably practicable. There are many factors other than the 

numerical estimate of risk that can contribute to the decision that no further action is 

justified, including: 

 The cost to reduce risks further; 

 The level of certainty or uncertainty on various aspects of the problem; 

 A precedent of comparable decisions on other projects; 

 The possibility that the concern is not reasonable to address in a practical manner; 

 

2

 Guidelines on Risk Assessment, Australian National Committee on Large Dams, October 2003. 

3

 Guidelines for Achieving Public Protection in Dam Safety Decisionmaking. U.S. Department of the Interior, Bureau 

of Reclamation, Denver, Colorado. June 15, 2003. 
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 The chance of success of an action; 

 Time to perform the remediation, and; 

 Other considerations. 

It should also be recognized that regardless of what actions are taken or not taken there will 

always be a certain residual risk. Therefore rather than ignoring or pretending that the risk is 

zero, it is appropriate that tolerable risk levels for various aspects of the dam be discussed 

and identified . 

V. Risk Management 

Risk management encompasses activities related to making risk-informed decisions, prioritizing 

evaluations of risk, prioritizing risk reduction activities, and making program decisions associated 

with managing a portfolio of facilities. Risk Management processes vary with respect to an 

organization’s dam safety governance. Risk Management is greatly facilitated and enhanced by 

having the base of knowledge supplied by the risk analyses and risk assessment inputs for the dams 

as described above. Such knowledge allows a logical and consistent basis for substantiating and 

prioritizing risk reduction activities and/or making program decisions associated with managing a 

portfolio of facilities. Risk management, by virtue of its use of the findings from a risk assessment / 

risk evaluation process, includes considering the environmental, social, cultural, ethical, political, 

and legal factors. Risk management should be regarded as an ongoing and iterative process that 

needs to adapt to new information. 

The primary goal of risk management is to implement actions to either: accept, further monitor or 

evaluate, control or reduce risk, while considering the cost and benefits of any actions taken. When 

reducing risk either at a single dam or within a portfolio of dams, actions should be taken as 

quickly and as efficiently as possible, recognizing that there will likely be limits on available 

funding. Consideration should be given to the amount of risk reduction achieved for the cost of 

achieving risk reduction. Generally the priorities will be to fix the dams with the highest perceived 

risk first (assuming there is confidence in the risk estimates), but if the cost of reducing risk at the 

highest risk dam is disproportional to the risk reduction achieved, it may be appropriate to consider 

risk reduction activities at other dams first. 

The agencies recognize that the methods used to calculate risks do not provide precise numerical 

results. Therefore, relying solely on the numeric estimates in comparison to definite established 

The following principles apply to risk assessment: 

10. Remedial actions should do no harm. 

11. Decisions should be risk-informed and not risk-based. 

12. Interim risk reduction measures should be considered and implemented where needed. 
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criteria (risk-based evaluation criteria) would not be appropriate. Decisions are generally more 

complex than can be portrayed using only the numerical results of a risk analysis. The strength of 

the dam safety case should also be considered in the risk management phase. 

In order to effectively prioritize dam safety actions, information on the cost of the actions, the risk 

reduction potential, and the duration of the actions is needed. This type of information is needed to 

evaluate the efficiency of risk reduction actions and can be used to fine-tune dam safety actions. A 

record of the baseline risks, the dam safety case and rating and updates that resulted from risk 

reduction activities should be maintained for each dam in an agency’s inventory. 

For federal dam owner’s with large dam inventories or for private dam owner’s with large dam 

inventories, prioritizing dam safety actions will be important, since funding will limit how quickly 

actions can be completed. If an owner is dealing with a large dam inventory, a risk categorization 

scheme may be helpful in making an initial cut at prioritizing dam safety actions. A method of 

categorizing dams by risk is outlined in Table 1. This will provide an initial sorting of dam safety 

actions, but further refinements within the categories will be needed. The following factors should 

be considered for refined prioritization (each of these factors will contribute to increasing the 

priority of actions at a given dam): 

 Both the failure probability and the annualized life loss exceed the threshold guideline 

values. 

 The failure probability or the annualized life loss is driven by a single potential failure 

mode. 

 The failure probability or the annualized life loss is driven by a potential failure mode 

manifesting itself during normal operating conditions. 

 The range of risk estimates is tightly clustered and the mean and median are similar (for 

detailed uncertainty analyses only) and/or sensitivity studies instill confidence. 

 Risk reduction or confirmation is relatively easy and inexpensive. 

The above factors can also be considered if a dam appears borderline between two categories. If a 

dam owner has a small inventory of dams, the above factors alone can be used as the basis for 

establishing priorities. The initial effort to place the actions in one of the five risk categories would 

have limited value for small dam inventories. 

Prioritization of dam safety actions can be done on a facility basis (where total risk is the focal point 

and the goal is to reduce total risk to tolerable levels) or on an individual potential failure mode 

basis (where single potential failure modes are addressed).
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URGENCY OF ACTION CHARACTERISTICS AND CONSIDERATIONS POTENT

I - VERY HIGH URGENCY

CRITICALLY NEAR FAILURE: There is direct evidence that failure is in progress and the dam is almost certain to fail during normal operations if action is not taken quickly. OR EXTREMELY HIGH RISK: Combination of life or economic consequences and likelihood of failure is very high with high confidence. 

 Take immediate action t

findings to potentially aff

 Implement interim risk re Ensure the emergency a

functionally tested. 

 Conduct heightened mo

investigations and actionreduction. 

 Initiate intensive manage

II - HIGH URGENCY 

RISK IS HIGH WITH HIGH CONFIDENCE OR VERY HIGH WITH LOW TO MODERATE CONFIDENCE: The likelihood of failure from one of these occurrences, prior to taking some action, is too high to delay action. 

 Implement interim risk re

 Ensure the emergency a

functionally tested. 

 Give high priority to heig

evaluation. Expedite invsupport long-term risk re

 Expedite confirmation of 

III - MODERATE URGENCY

MODERATE TO HIGH RISK: Confidence in the risk estimates is at least moderate. 

 Implement interim risk re

 Ensure the emergency a

functionally tested. 

 Conduct heightened mo

investigations and actionreduction. 

 Prioritize confirmation of 

IV – LOW TO MODERATE URGENCY

LOW TO MODERATE RISK: The risks are low to moderate and confidence in the risk estimates is low with the potential for the potential for the classification to move higher, with further study. 

 Ensure routine risk mana

 Determine whether actio

periodic review 

 Before the next periodic 

measures and schedule 

 Give normal priority to in

classification, but do not at this time. 

V – NO URGENCY LOW RISK: The risks are low and are unlikely to change with additional investigations or studies.  Continue routine dam sa

and normal operations a

Table 1 – Proposed Joint Federal Risk Categories Table
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VI. Section 4 – Risk Communication / Public Awareness 

Communication is important in all aspects of dam safety - within an organization, with the public 

and with the specific owners or stakeholders of a project. However, communication about the work 

associated with risk is particularly important because of the fears, sentiments, perceptions, and 

emotions surrounding the word risk and the use of risk analysis in engineering. 

Thus, it is important to understand and have a good plan for communication risk, including: 

 What information is available at a given dam related to potential failure modes and how the 

information is considered in a risk analysis; 

 How risk will be considered by an organization; 

 What the results of the risk analyses are, and; 

 What decisions were reached and what risk remains. 

This communication can help create an awareness of potential dam safety issues and help all parties 

gain a greater understanding. Creating an understanding of risk and dam safety issues is important 

within an organization, among the public, and among owners and stakeholders who have varying 

degrees of connections to the dam and the associated potential impacts. Those groups have a 

variety of backgrounds, experience, and sophistication. Communication plans and strategies should 

be developed for the following: 

The following principles apply to risk management: 

13. The objective of an organization should be to reduce dam safety risk as effectively and 

as efficiently as possible. 

14. Each organization should have a transparent process for establishing priorities and the 

urgency of completing dam safety actions. 

15. Incorporate flexibility in prioritizing work within a portfolio, allowing for adjustments 

in planned work as new high priority issues are identified. 

16. Use a dedicated, established group to review and prioritize proposed dam safety actions 

within a portfolio or when establishing urgency for action at a specific dam. 

17. Independent review is critical to the credibility of this process. 

18. The urgency of completing dam safety actions should be commensurate with risk 
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 Internal to a dam safety organization; 

 Owners and stakeholders; 

 Dam site and project personnel; 

 Local organizations; 

 Technical organizations or consultants; 

 Decision-makers, and; 

 The public. 

A. Internal Communication within a dam safety organization 

There are at least four levels at which communication garnered from risk studies and resulting 

decisions need to take place within an organization. These include: 

 Communication from and to employees at the dam or project site, 

 Communication at the local level of the organization, where the responsibility for 

managing the operation, maintenance and the routine visual surveillance and instrumental 

monitoring for the suite of dams associated with one or more projects typically resides; 

 Communication at the technical level where traditional engineering and geologic studies 

and investigations are performed, where risk analyses and risk assessments are carried out 

and where independent staff check and review studies, analyses and risk analysis results; 

and 

 Communication at the decision making level, where funding is secured and decisions are 

made regarding dam safety actions and risk management decisions on program priorities 

are made. 

1. Dam Site and Project Site Personnel 

The dam tenders, inspectors, staff performing visual inspections and taking readings of seepage and 

instruments, and plant operators responsible for gate operations provide a valuable source of ground 

truth relative to risk analyses and need to be communicated with in that regard. Dam operators often 

have detailed information and understanding of the dam history, past performance issues and a good 

perspective on perceived changes at the dam. It is important to include them in risk analysis 

activities to benefit from their knowledge of the dam and it is very important for them to gain an 

understanding of potential failure modes at the dam, specific locations at the dam where potential 

failure modes might develop and the initiating mechanisms for the potential failure modes. This 

will allow them to more effectively monitor the dam. Likewise the results of risk analyses and the 

decisions and rationale used in risk assessment and risk management need to be provided to these 

personnel such that they have a full understanding of the outcome of the risk process. 

2. Local Level of an Organization 

Supervision and management of the operation of a number of projects and dams is usually the 

responsibility of a local office within a dam safety organization. These offices have the 

responsibility for the staffing for routine operation and maintenance of the projects and dams under 

their purview as well as inspection and monitoring of the dams. In addition they are often 
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responsible for implementing structural and non-structural actions which may be specified as the 

outcome of the risk informed decision analyses. Often these local offices cover a number of 

facilities and manage a staff that must distribute their time between several sites. Local office 

personnel, as appropriate, also need to be consulted and included in risk analyses relative to failure 

modes and dam performance either because they have previously been assigned to dams under their 

purview and have an intimate historic knowledge and/or they have a broader perspective by virtue 

of being associated with all the projects and dams under their responsibility. With respect to 

communicating the findings from the risk analyses, and the decisions from risk assessment and risk 

management, the local office is typically the key intermediary between the desired objectives of the 

organization’s dam safety office and the field site where these outcomes are to be effected. 

3. Technical Elements of an Organization 

Detailed communications are required among the technical staff (including consultants and 

contractors) performing the basic analytical studies and evaluations, the persons performing the risk 

analyses and the staff performing the risk studies who will be reviewing studies, analysis reports 

and risk analysis reports and making their assessments on specific dams and dam safety issue 

evaluations. The reports prepared by each previous study level will need to include sufficient detail 

so the primary reviewers (as well as analysts in future years) can understand assumptions made, 

detailed results of studies, analyses and risk analyses and the technical basis for overall findings. 

Further, these results made be called for at any future stage in the process (risk management, 

stakeholder review, etc,) and thus good documentation is essential. Briefings are typically 

performed for technical staff on the results of studies, risk analyses, the overall findings and the 

dam safety case for proposed actions. Briefings may also be performed for consultant review 

boards, which provide an independent review of studies and findings. At this level the 

communication will be the most demanding technically. 

4. Decision making Level of an Organization 

Decision makers need to have a general understanding of the potential failure modes at a dam, the 

results of studies and analyses performed, the risk analysis results and the dam safety case. 

Decision makers have the responsibility for formally accepting dam safety actions and must be 

convinced that the proposed actions are warranted and appropriate. Summary technical information 

is typically presented in briefings for decision makers and the detail needs to be sufficient to support 

the key findings and dam safety case. Individuals who have the responsibility for setting priorities 

within an organization will also need to understand the basis and urgency of dam safety actions at a 

given dam. This is needed to prioritize actions across an entire inventory. 

B. Communications with Stakeholders

Risk communication with and including stakeholder or owner participation are important 

elements to be successful. Risk communication and stakeholder participation should ensure: 

(1) responsible and affected stakeholders will be partners and afforded the opportunity to 

participate in decisions that affect them, and (2) communications regarding potential 

inundation hazard, consequences, and shared solutions will be open, transparent and 

understandable. 

It may be helpful to include individuals from stakeholder organizations as observers in the 

risk analysis and especially in the risk assessment meetings. This will allow those 

individuals to gain a better understanding of the basis of the risk analysis estimates, the 

subsequent findings and the rationale on which a decision is made. They will typically be 

interested in the rationale behind proposed dam safety and will want to ensure that the 
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chosen actions are appropriate and efficient. It will also be helpful to explain the overall 

dam safety process used and explain the risk guidelines that were used in the risk 

assessment. Funding partners may enlist consultants to review reports, attend briefings and 

interact with technical staff. Detailed technical reports and briefings may need to be 

provided for consultants 

C. Communications with the organizations and the public 

impacted by the dam 

Communications should also be provided proactively for organizations and the public that 

will be, could be, or consider themselves impacted by a dam failure or by dam safety actions 

that will restrict or modify the operations at the dam. These communications should be 

initiated at the planning or investigation stage so as to inhibit development of erroneous 

information and rumors. Such presentations need to be appropriately technical – conveying 

the technical information in a manner that conveys the key issues and concerns at the dam, 

the potential impacts of a dam failure, the proposed actions to address the issues/concerns 

and the impacts of these actions on organizations and the public and the costs and schedule 

for the dam safety actions, but avoids technical jargon and detailed technical presentations. 

Information should be presented in a clearly understandable manner but not in a way that is 

condescending to the audience. The diverse audience that attends the public and stakeholder 

meetings may will include persons who can fully comprehend the technical content being 

presented and a sure fire way to alienate the audience is to presume they are incapable of 

understanding the work that is planned or has been done. Technical staff should be 

available to answer detailed technical questions from individuals with technical backgrounds 

that may attend the briefing. Organizations may have security concerns related to 

information that is presented in these general briefings or public meetings and the 

presentations may have to be adjusted to take this into account. 
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.

The following principles apply to risk communication: 

19. Enhance communication to the public and internally within dam owning and regulating 

organizations (EMAs). 

20. Emergency Action Plans and communication with the public is an important and 

integral aspect of reducing risk to life. 

21. Communications should be open and transparent. 

22. When presenting dam safety issues at a given dam, focus on the benefits and the risks 

posed by infrastructure. 

23. Integrate risk communications early in the process of responding to dam safety issues. 

24. Provide context for risk communications (compare with other risks). 

25. Focus communications on actions that individuals/organizations need to take. 

26. Discuss uncertainty in risk esimates and the dam safety case: 

a. What you’re certain of. 

b. What is likely but not certain. 

c. What is possible but not likely. 
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VII. Appendix A – Guideline on Risk Terminology

To facilitate the cooperative agreement with respect to all elements of Risk Based Decision 

Analysis it is extremely valuable to use common terminology and have a common understanding of 

that terminology. It is recognized that this is not a simple task as the words related to dam safety 

risk have been used in different ways by the member agencies over the years since their initial 

application over thirty five years ago, however, toward the end of establishing consistency in 

terminology, the guideline provides definitions of the terms given below that are used in Risk 

Management, Risk Assessment, Risk Analysis and Risk Evaluation. 

Risk – The product of the likelihood of a structure being loaded, adverse structural performance, 

(e.g. dam failure) and the magnitude of the resulting consequences. 

Risk Analysis / Risk Estimation – A qualitative or quantitative procedure that identifies potential 

modes of failure and the conditions and events that must take place for failure to occur and then 

obtains (for a quantitative analysis) a numerical estimate of the risk of adverse consequence 

multiplying the probability of load times the probability of dam failure given the load times the 

magnitude of adverse consequence given dam failure. 

Risk Assessment – The process of considering the quantitative or qualitative estimate of risk along 

with all related social, environmental, cost, temporal and other factors to determine a recommended 

course of action with regard to mitigating or accepting the risk. 

Risk Management – actions implemented to communicate the risks and either accept, avoid, 

transfer or control the risks to an acceptable level considering associated costs and benefits of any 

action taken. 

Risk Evaluation – Risk evaluation is the qualitative or quantitative description of the nature, 

magnitude and likelihood of the adverse effects associated with a hazard. A risk evaluation often 

includes: one or more estimates of risk; risk description; risk management options; economic and 

other evaluations; estimates of changes in risk attributable to the management options. 

Residual Risk – Risk remaining at any time. 

Risk Governance – The process of risk-informed decision-making and the process by which riskinformed decisions are implemented. 

Uncertainty - Uncertainty is the result of imperfect knowledge concerning the present or future 

state of a system, event, situation, or population under consideration. 

Tolerable Risk - A risk within a range that society can live with so as to secure the benefits 

provided by the dam. It is in the range of risk that we do not regard as negligible or as something 

we might ignore, but rather as something that we need to keep under review and reduce it still 

further as we can. 

Dam Failure – Failure characterized by the sudden rapid and uncontrolled release of impounded 

water. It is recognized that there are lesser degrees of failure and that any malfunction or 

abnormality outside the design assumptions and parameters that adversely affect a dam’s primary 

function of impounding water could be considered a failure. 
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Potential Failure Mode – A way that dam failure can occur (i.e., the full sequence of events from 

initiation to failure) for a given loading condition.