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CHAPTER THREE
Current Dam and Levee
Infrastructure, Management,
and Governance
This chapter summarizes current dam and levee physical infrastructure, and manage-
ment approaches with respect to safety, including methods and standards used in design,
inventory, operation and maintenance, and emergency management. It also addresses the
governance framework in place to facilitate and guide dam and levee safety, including the
legal framework and the roles and authorities of agencies at different levels. Gaps in current
practice and governance related to fostering community resilience are identified. Because
policies, management, and jurisdictional responsibility for safety differ between dams and
levees, this chapter describes dam and levee issues separately.
“Safety” to many dam and levee professionals is associated primarily with reducing the
likelihood of flooding. Dam safety efforts since the 1972 failure of Buffalo Creek Dam1 have
therefore focused on strengthening safety programs, reducing the potential for future failures,
conducting periodic inspections, remedying deficiencies, and preparing emergency action
plans (EAPs). Progress in those endeavors has been substantial on a national scale. There
has also been consistent movement in recent years toward risk-informed dam safety assess-
ments among many dam owners. Development of EAPs and the carrying out of tabletop and
full-field exercises have also become established dam safety practices among many owners.
Despite such challenges as limitations in safety program resources, a large number of
dams rated as having “high” or “significant” potential of death or loss of property in the event
of failure (see Box 3.1 for description of the rating system) are inspected in a timely manner
according to guidance from the Association of State Dam Safety Officials (ASDSO)2 (e.g.,
Information about the Buffalo Creek Dam failure can be found at www.wvculture.org/history/disasters/buffcreek
1
govreport.html (accessed December 23, 2011).
ASDSO was established in 1983 and represents state, federal, and local dam professionals, academics, and manu-
2
facturers and suppliers. The organization was established to provide guidance for nonfederal dam owners. Although it holds
no regulatory authority, it has played a major role in coordinating dam safety efforts across the country and between the states
and the federal agencies. It has been the major advocate for dam safety policy, technical guidelines, and training. See www.
damsafety.org/about/?p=1ca717dd-18d5-4803-a7eb-cd45aad31210 (accessed February 7, 2012).
49
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
BOX 3.1
Dam and Levee Hazard Classification
The National Inventory of Dams (NID) hazard classification system (see Table 1) is broad, qualitative,
and based on the potential threat to life and property in the event of dam failure. The criteria for inclusion
in the inventory are provided in Table 2. A dam is given a “high” hazard rating if its failure can result in
fatalities, whether the dam is small or large and has the potential for a single or thousands of fatalities. The
rating is also regardless of its condition (e.g., its likelihood of failure). Current emphasis is appropriately
on high-hazard dams, but there can be a wide disparity in the consequences of failures of these structures.
Other consequences of dam failure, such as economic and environmental losses, are qualitatively evaluated
TABLE 1 Hazard Classification for Dams
Likelihood of Economic, Environmental, or
Hazard Classification Likelihood of Loss of Human Life Lifeline Loss
Low None expected Low and generally limited to owner
Significant None expected Yes
High Probable; one or more expected Yes (but unnecessary for this classification)
SOURCE: FEMA (2004b).
ASDSO, 2005). As a result of these inspections, many dams have undergone safety modifi-
cations for hydrologic, seismic, and other deficiencies. But efforts to improve dam safety are
not complete; about half of the dams that should have EAPs do not (Altinakar et al., 2008;
see Box 3.2), and there is a backlog of safety repairs to be addressed. Moreover, improving
safety needs to be a continuing and adaptive process that is responsive to changing structural
and societal conditions. The concept of safety among dam and levee professionals has not
evolved beyond reducing the likelihood of failure.
DAM AND LEVEE INFRASTRUCTURE
Before a community can address risks associated with dam or levee failure, it must
know that a dam or levee is present and poses risk. Information on dam and levee loca-
tion, physical properties (e.g., size and type), design requirements, ownership, maintenance
responsibility, and regulatory framework is critical for understanding the hazards and risks
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Current Dam and Levee Infrastructure, Management, and Governance
and defined in equally broad terms. The hazard classification process does not include an assessment of
the sociological or other effects on a community, nor does it consider the broader local and regional effects
(economic and other) of the loss of a critical infrastructure (power, water supply, flood protection). Hazard
classification is assigned primarily by state or federal regulatory agencies. The Federal Emergency Manage-
ment Agency guidance states that classifications “should be based on the worst-case, probable scenario of
failure or mis-operation of the dam, i.e., the assigned classification should be based on failure consequences
that will result in the assignment of the highest hazard potential classification of all probable failure and
mis-operation scenarios” (FEMA, 2004b, p. 7).
TABLE 2 National Inventory of Dams, Dam or Reservoir Size Criteria
Categorya Criteria Excluded
Dam height Over 25 ft 6 ft or lower, regardless of
reservoir capacity
Reservoir size At least 50 acre-ft Maximum, 15 acre-ft or less,
regardless of dam height
Hazard Any dam that poses a “significant threat to hu-
man life or property in the event of its failure”
Height is measured from the dam crest to the downstream toe; size is reservoir impoundment capacity.
a
SOURCE: USACE (2011a).
associated with the infrastructure. The National Inventory of Dams (NID) and the National
Levee Database (NLD) were established to provide information about dams and levees in
the country. The next sections describe those inventories and information in them about
dam and levee physical infrastructure and ownership.
National Inventory of Dams
The National Dam Inspection Act of 1972,3 passed after the failure of multiple dams,
required the U.S. Army Corps of Engineers (USACE) to create the NID. The first ver-
sion of the NID was delivered in 1975, and is generally updated on a 2-year cycle (the last
update was in 2009).4 Since 1975, the NID has been managed by USACE or the Federal
See Public Law 92-367 (available at npdp.stanford.edu/ndia.html).
3
See damsafety.org/media/Documents/PDF/2009NIDupdate_March2010.pdf.
4
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
BOX 3.2
Emergency Action Plans
An Emergency Action Plan (EAP) identifies the actions and responsibilities of different parties in the event
of an emergency, including uncontrolled flow from a reservoir or other controlled waters. As defined by FEMA
(1998, p. 3), an EAP for a dam is
a formal document that identifies potential emergency conditions at a dam and specifies pre-planned
actions to be followed to minimize property damage and loss of life. The EAP specifies actions the
dam owner should take to moderate or alleviate the problems at the dam. It contains procedures and
information to assist the dam owner in issuing early warning and notification messages to responsible
downstream emergency management authorities of the emergency situation. It also contains inundation
maps to show the emergency management authorities the critical areas for action in case of an emergency.
The requirements for EAPs are established by dam safety regulatory agencies at the national level, by such
individual agencies as the Federal Energy Regulatory Commission, or by individual states. Figure 1 indicates that
48 percent of high-hazard dams that should have EAPs do not (Altinakar et al., 2008). Figure 2 indicates that
about 71 percent of significant-hazard dams do not have EAPs (Altinakar et al., 2008). EAP oversight occurs pri-
marily at the state level, but EAPs are examined by the Association of State Dam Safety Officials and the National
Dam Safety Review Board. The latter two organizations have no authority to mandate revisions of EAPs to make
them more effective, and state agencies often operate under tight budgets, making EAP oversight a challenge.
Nevertheless, EAPs serve important functions for the dam owners and the broader community. Consequences of
not having an EAP have been demonstrated, for example by the 1982 failure of the Lawn Lake Dam in the Rocky
Mountain National Park in Colorado which caused the deaths of three people and $31 million in damage (NPS,
2004). A district court found that the government “in creating this relationship with citizens, also creates a duty
for itself to develop orderly procedures for dealing with emergencies.”a
EAP effectiveness is dependent on the correctness of the underlying assumptions (e.g., accurate estimation
of risks and appropriate responses), reasonable care in the regular review and modification of plans, and ap-
propriate education and training of those with responsibility in the execution of the plan.
See Coates v. United States, 612 F. Supp. 592 (C.D. Ill. 1985).
a
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Current Dam and Levee Infrastructure, Management, and Governance
FIGURE 1 (a) Classification of high-hazard dams by height vs status of EAPs. (b) Classification by age vs status of EAPs. Based
on entries in National Inventory of Dams as of September 28, 2008. Y = Yes, EAP exists; NR = EAP not required; and N = No,
EAP does not exist. SOURCE: Modified from Altinakar et al. (2008). Used with permission from the authors, copyright 2012.
Figure 1A in Box 3.2
Figure 1B in Box 3.2
Bitmapped,
Bitmapped,
low-res
low-res
FIGURE 2 (a) Classification of significant-hazard dams by height vs status of EAPs. (b) Classification by age vs status of EAPs.
Based on entries in National Inventory of Dams as of September 28, 2008. Y = Yes, EAP exists; NR = EAP not required; and N = No,
EAP does not exist. SOURCE: Modified from Altinakar et al. (2008). Used with permission from the authors, copyright 2012..
Box 3-2 gure 2B
Figure 2A in Box 3.2
Bitmapped,
Low-res 53
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
Emergency Management Agency (FEMA). It is currently maintained and updated by
USACE. Before the September 11, 2001, terrorist attacks on the United States, the NID
was freely accessible online and distributed on CD. The NID is still online,5 but informa-
tion on hazard classifications, locations of nearest downstream towns, and dam conditions
are password protected and not available to nongovernment users.
The NID includes information about the location, physical characteristics, dam type,
foundation type, designer, owner, and hazard-potential classification of about 84,000 dams.
Dams in the database are more than 25 ft high, hold at least 50 acre-ft of water, or are
considered to pose a significant hazard if they fail (USACE, 2011a). Dams included in the
NID meet the criteria listed in Table 2 of Box 3.1. The hazard-class distribution of all dams
in the NID is shown in Figure 3.1. High-hazard dams (at least one death expected in the
event of failure) make up almost 17 percent of the inventory. Some 31 percent of the dams
in the inventory (those classified as having high or significant hazard potential) are expected
to result in economic, environmental, and lifeline losses in the event of failure. Because the
states have primary regulatory authority over dams, and because they have different criteria
for defining the dams they regulate, the available information on dams that meet the NID
criteria varies. Figure 3.2 shows the distribution of dams in the NID. Box 3.3 provides some
statistics about the nation’s dams derived from the NID.
Since its development, there have been concerns about the accuracy and complete-
ness of the NID. Recently, for example, the state of Washington conducted a focused
survey to identify nonpermitted dams that should be in the inventory and regulated by
the state ( Johnson, 2010).6 The survey identified 28 dams classified as high-hazard dams
(including 11 that had safety deficiencies requiring immediate attention) and 11 classified
as significant-hazard dams. According to Washington state, high-hazard dams are those
whose failure would place three or more homes at risk downstream, and significant-hazard
dams one or two homes.7
National Levee Database
The NLD is less mature than the NID, having been initiated as a result of the National
Levee Database Authority (Public Law 109-148) following Hurricane Katrina. The NLD
was constructed and populated under the authority of USACE and made available online
to the public on October 27, 2011. To date, it contains information only on USACE levees.
Although the National Levee Database Authority calls for inventorying all levees in the
country, state and federal funding has not been made available to gather data on nonfederal
levees.
See nid.usace.army.mil (accessed November 4, 2011).
5
Washington State has jurisdiction over any dam that can impound 10 or more acre-ft of water at the dam crest.
6
See WAC 173-175-130, Engineering Design Reports (available at apps.leg.wa.gov/WAC/default.aspx?cite=173-175-130).
7
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Current Dam and Levee Infrastructure, Management, and Governance
FIGURE 3.1 Hazard-class distribution of dams in the United States. SOURCE: USACE (2012).
Figure 3-1
bitmapped
pretty low-res
FIGURE 3.2 Distribution of dams cataloged in the National Inventory of Dams. Red dots indicate
high-hazard dams; yellow dots indicate significant-hazard dams; and black dots indicate low-hazard
Figure 3-2
dams. Hazard classification refers to the consequences of a dam’s failure or misoperation, not to its condi-
Bitmapped,
tion. SOURCE: USACE (2011a).
Low-res
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
BOX 3.3
Characteristics of U.S. Dams Based on the National Inventory of Dams
About 84,000 dams are described in the National Inventory of Dams. Figures 1 and 2 show the distribution
of dams by type (e.g., earth or rock embankments and concrete gravity) and by height, respectively. About half
the dams are 25 ft or less in height, and the vast majority are earth embankments. Figure 3 shows the distribution
of dam completion dates as listed in the NID. About one-third are older than 50 years, and by the end of this
decade, about 56 percent will be older than 50 years. Figure 4 shows the distribution of dam ownership in the
United States. Nearly 69 percent of dams are privately owned, and less than 4 percent are owned by the federal
government. Federally owned dams, however, include many of the largest dams in the country (e.g., Hoover Dam,
Grand Coulee Dam, and Bonneville Dam). Only a small percentage of dams in the United States pose a risk to
communities.
FIGURE 1 Distribution of dams
by type in United States.
SOURCE: USACE (2012).
Figure 1 in box 3-3
Bitmapped
FIGURE 2 Distribution of dams
by height in United States.
SOURCE: USACE (2012).
Figure 2 in box 3-3
Bitmapped
56
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Current Dam and Levee Infrastructure, Management, and Governance
FIGURE 3 Distribution of
dams by date of completion
in United States. SOURCE:
USACE (2012).
Figure 3 in box 3-3
Bitmapped
FIGURE 4 Distribution of
dams by ownership in United
S tates. SOURCE: USACE
(2012).
Figure 4 in box 3.3
Bitmapped
57
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
FIGURE 3.3 Distribution of levees by ownership in the United States. SOURCE: NCLS (2009).
Figure 3-3
Tens of millions of people reportedly live behind levees (NCLS, 2009). The NLD
Bitmapped
describes about 14,700 mi (22,500 km) of USACE levees.8 Little is known about the size
of the national levee portfolio, especially about levees not under federal jurisdiction. It is
estimated that there may be 14,000–16,000 mi (22,500–26,000 km) of levees operated by
agencies other than USACE. The National Committee on Levee Safety (NCLS) estimates
there may be up to 100,000 mi (161,000 km) of nonfederal levees in the nation (see Figure
3.3). Integration of levee data collected by the FEMA National Flood Insurance Program
(NFIP) into the NLD, which is under way, will increase the total number of miles of levee
systems in the NLD. More than 21,000 communities currently participate in the NFIP
(FEMA, 2011b).
An NLD steering committee that comprises USACE and state representatives has
been formed, in part, to begin integrating information on nonfederal levees into the NLD.
Some states are making their own efforts to inventory levees. In California, for example,
the Department of Water Resources has built a levee database of its estimated 9,000 mi
(14,500 km) of nonfederal levees since 1997,9 effort on which increased after Hurricane
Katrina. The inventory is about 30-40 percent complete; a target date for completion has
not been set. USACE is developing guidance and providing assistance to states to improve
submission of voluntary information for the NLD.
The National Committee on Levee Safety has proposed a levee hazard potential clas-
sification system, shown in Table 3.1, similar in overall structure to that for dams (NCLS,
2009). USACE has used this hazard classification system for some of its levees, but
See www.usace.army.mil/LeveeSafety/Activities/Pages/act_nldb.aspx (accessed November 1, 2011).
8
S. Ekanayake, CA DWR, personal communication, August 10, 2011.
9
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Current Dam and Levee Infrastructure, Management, and Governance
TABLE 3.1 Proposed Hazard Potential Classification for Levees
Number of
Number People Potentially
Hazard- of People Inundated
Potential Potentially to Depths of
Classification Inundated 3 ft or More Additional Considerations
High >10,000 >10,000 Includes areas of consequences where critical
life-safety infrastructure is at risk (e.g., major
hospitals, regional water treatment plants, and
major power plants)
Significant >1,000 <10,000 Includes areas of consequence where the
number of people potentially inundated is low,
but there may be significant potential for large
economic impacts or losses
Low <1,000 0 —
NOTE: These classifications use parameters and definitions consistent with those in use by other agencies.
For example, California defines an urban area as having 10,000 people and subject to higher flood pro-
tection requirements (Senate Bill 5), and FEMA considers shallow flooding to be less than 3 ft (see www.
fema.gov/plan/prevent/floodplain/nfipkeywords/sfha.shtm). SOURCE: NCLS (2009).
inspection ratings are not included for most levee systems in the NLD. In October 2011,
the state government website Governing.com reviewed 744 levee ratings listed in the NLD:
77 percent were found to be rated “minimally acceptable,” indicating minor deficiencies that
would not impair levee performance; 12 percent were rated “unacceptable,” indicating they
are not expected to provide reliable flood protection; and the remaining 10 percent were
rated “acceptable,” indicating they were in satisfactory condition and expected to function
(Maciag, 2011). Many of the levees rated as unacceptable may be as much as 70 years old.
Frequent inspections are critical for understanding the condition of levees and the
risks that they pose. Updating the NLD with new information is important not only for
appropriate risk assessment but also because the NLD could influence how priorities for
infrastructure funding are set. Levees operated by USACE undergo routine annual inspec-
tions and comprehensive inspections every 5 years. The NLD will be updated regularly as
levee conditions change. States might not follow the same inspection schedules.
DAM AND LEVEE SAFETY PROGRAMS
ASDSO distributed a questionnaire to individual state dam safety officials in 2006 to
determine what authorities and activities to manage and regulate levee safety existed in the
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
spawned a variety of initiatives and technical guidance at different levels of government and
in other organizations established to facilitate dam operation and maintenance.
In 1979, President Carter signed Executive Order 12148, creating FEMA. Also in
1979, the Ad Hoc Committee on Dam Safety (1979) released the first federal dam safety
guidelines for federally owned dams. The guidelines were management oriented, not techni-
cal, and remain the basic principles for dam safety. The first formal NDSP was authorized
in 1986 as part of the Water Resources Development Act16 and created the NID, a first
National Dam Safety Review Board (NDSRB), and provided for assistance to states.
In 1996, the National Dam Safety Program Act17 was passed, It placed the NDSP
under the director of FEMA and expanded the NDSRB to advise the director. The direc-
tor was given no regulatory authority over dam safety but was charged with “encouraging
the establishment and maintenance of effective federal and state programs, policies and
guidelines”18 National security considerations were added to the legal framework in 2002,
and the program was reauthorized again in 2006.19 Since 1996, the Interagency Committee
on Dam Safety (ICODS)20 has generated and released a series of guidance documents in an
attempt to provide a uniform and consistent dam safety framework for federal, state, and
private dam owners and regulators. The guidance, however, is not mandatory.
The nation has evolved from total dependence on dam owners to demonstrate “due
diligence” with respect to dam safety in the first half of the 20th century, to the development
of guidelines and regulations for the safety of federal dams in midcentury, and to guidance
to encourage best practices among the states (as owners and regulators) and private owners
by the end of the century. In the 21st century, dam safety remains a distributed responsi-
bility of many agencies and owners. FEMA has oversight but no regulatory authority for
implementing safety. In most cases, nonfederal owners are responsible for safety.
Table 3.2 highlights federal agencies that have responsibilities related to the safety of
dams they own or regulate in the United States. As already stated, FEMA has oversight
of the NDSP and provides guidelines that are the foundation of dam safety policy but has
no management or regulatory authority over dam owners or operators. That responsibility is
vested in individual federal agencies that construct, own, operate, and regulate dams under
laws and policies as discussed above. Dams not expressly the responsibility of a federal
agency—the majority in the NID—are regulated by the states. Individual agencies and the
states supplement legislation and policies to reflect state management structures and finan-
cial responsibilities.
See www.fws.gov/policy/361fw1.html.
16
The National Dam Safety Act was passed as part of the Water Resources Development Act of 1996. See epw.senate.
17
gov/dam.pdf.
See epw.senate.gov/dam.pdf.
18
See www.fws.gov/policy/361fw1.html.
19
ICODS, established in 1980, is chaired by FEMA to serve as a forum to coordinate federal activities related to dam
20
safety and security. See www.fema.gov/plan/prevent/damfailure/partners.shtm (accessed February 7, 2012).
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TABLE 3.2 Roles of Federal Agencies in Dam Safety
Agency Primary Roles Dams Under Jurisdiction
Federal Emergency Lead agency for National Does not own any dams
Management Agency Dam Safety Program; chairs
National Dam Safety Review
Board and Interagency
Committee on Dam Safety
U.S. Department of Owns or regulates dams; More than one-third of dams in
Agriculture (USDA) supports private owners with National Inventory of Dams (NID) are
planning, design, finance, and associated with USDA
construction
Department of Defense Plans, designs, finances, DOD has a total of 267 dams under its
(DOD) constructs, owns, operates, jurisdiction on military lands
and permits dams; limited to
military lands with exception of
USACE civil works programs
U.S. Army Corps of Plans, designs, constructs, Jurisdiction over USACE dams, dams
Engineers operates, and regulates dams; constructed by USACE but operated by
permits and inspects dams others, and other flood control dams
subject to federal regulation; 631 dams
in the NID are associated with USACE
Department of the Plans, designs, constructs, About 2,000 dams in the NID under
Interior operates, and maintains dams five bureaus
Department of Labor Regulates safety- and health- About 1,400 dams under Mine Safety
related aspects of miners and Health Administration
Federal Energy Issues licenses for, provides 2,530 dams in the NID affecting
Regulatory Commission inspections of, and regulates navigable waters
nonfederal dams with
hydroelectric capability
Tennessee Valley Plans, designs, constructs, 49 dams in Tennessee River Valley
Authority operates, and maintains dams
SOURCE: FEMA (2009).
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
Table 3.3 summarizes dam safety governance, guidance, and standards. The principal
governance documents are provided in FEMA federal guidelines. Other guidance and
standards, mostly technical, come from FERC, USACE, and the Bureau of Reclamation. A
single technical specification (e.g., using the probable maximum flood for spillway design)
can dominate design considerations.
There have been substantial improvements in dam safety practice, but in general, prac-
tice fails to take a systems approach in its efforts. For example, the development of the
Potential Failure Mode Analysis (PFMA) process (FERC, 2005) requires a deliberate effort
to systematically identify and document all potential modes of failure of a dam from all
sources. PFMA is used by the Bureau of Reclamation, USACE, FERC, and others in the
dam safety community, however, PFMA, as currently applied, lacks a systematic basis for
relating the infrastructure-based analyses to the larger river system or to the communities
at risk. Thus the utility of PFMA in terms of risk-informed decision making is limited.
The PFMA process will likely continue to be used, but the practice could be improved if
it evolved to recognize and address epistemic sources of uncertainty, became more detailed
to address modes of failure unique to different initiating events (e.g., earthquakes), and was
executed using a systems analysis approach in which interactions and interdependencies
between system elements are evaluated.
Another substantial evolution in guidance provided at the federal level has been the
development of a risk assessment framework for dams. It has come about particularly in a
collaborative effort between USACE, the Bureau of Reclamation, and FERC. Figure 3.4
outlines the emerging Federal Dam Safety Portfolio Risk Management Process (USACE,
2011b). This process employs the Dam Safety Action Classification (DSAC), a categori-
zation scheme ranging from “Urgent and Compelling” to “Normal” for safety-related ac-
tions. Interim risk reduction measures (IRRMs) are formulated and undertaken for dams
not considered tolerably safe until more permanent remedial measures are implemented.
The authority for applying risk has existed for some time (USACE, 2006); it is becom-
ing a reality. Application of risk measures will be important in moving from deterministic
standards-based approaches to estimating and applying resilience measures that include
both the probability and consequence components of risk assessment.
Levee Safety LawS and PoLicieS: HiStoricaL Setting, organizationaL roLeS,
guidance, and StandardS
The principal laws and policies that shape the governance of levee safety in the United
States are provided in a simplified chronological list in Appendix C as Table C.2. Just as
for laws that define dam safety policy, many laws related to levee safety have been amended
multiple times. Because the legal and policy setting for levees is less mature than that for
dams, there is less definitive legislation, policy, and technical and management guidance.
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Current Dam and Levee Infrastructure, Management, and Governance
TABLE 3.3 Dam Safety Governance-Related Guidelines and Standards
Responsible Agency Publication Scope
Interagency Committee on Dam FEMA 93: Federal Guidelines Federal agency owners; addresses
Safety for Dam Safety, (FEMA, management practices; no
2004c; reprinted from 1979) technical standards
Federal Emergency Federal guidelines for dam Technical guidelines that augment
Management Agency safety: FEMA 93 and create a big-picture
framework for state dam safety
FEMA 64: Emergency Action programs
Planning for Dam Owners
(FEMA, 1998)
FEMA 333: Hazard Potential
Classification System for Dams
(FEMA, 2004b)
FEMA 65: Earthquake Analysis
and Design of Dams (FEMA,
2005)
FEMA 94: Selecting and
Accommodating Inflow Design
Floods for Dams (FEMA,
2004d)
FEMA 148: Glossary of Terms
( FEMA, 2004a)
Federal Energy Regulatory Chapter 14: Engineering Dam Safety Performance
Commission Guidelines updated July 1, Monitoring Program and Potential
2005 (FERC, 2005) Failure Modes Analysis
U.S. Army Corps of Engineers ER 1100-2-1156, Safety of New Policy on application of risk
Dams—Policy and Procedure and portfolio methods to dam
(USACE, 2011b) safety throughout USACE
Bureau of Reclamation Dam Safety Risk Analysis Best Summary of best practices in
Practices Training Manual spectrum of technical subjects
(USBR, 2011a) relevant to dam safety;
collaborative with USACE
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
Federal Dam Safety Portfolio Risk Management Process
U.S. Army Corps of Engineers
U.S. Bureau of Reclamation
Federal Energy Regulatory Commission
DSAC
Classification
Routine
Implement Risk Inspections
Management Normal O&M
Measures Monitoring
Ongoing
For
All Dam Safety
Dams Modification Study Intermediate
Additional
including Risk Inspections
Issues
Assessment
Periodic
DSAC Classification,
Inspection and
Decision about Tolerable
Risk
Risks, Update IRRM
Assessment
Does the Incident or
Issue
Incident or
Inspection Finding Trigger
Evaluation
Special
Yes
DSAC Review and IRRM?
including Risk
Inspection
Assessment
No
FIGURE 3.4 Schematic of emerging Federal Dam Safety Portfolio Risk Management Process. Green
boxes represent routine dam safety processes executed under the federal dam safety guidelines (outer
loop) or nonroutine safety processes (inner loop). For any process, “yes” indicates further effort and an-
Figure 3.5
other decision; “no” indicates return to routine activities. Scrutiny of a potential problem (yellow diamond)
triggers a nonroutine process, and a decision made regarding if and what actions are necessary, and if
actions taken have been sufficient. DSAC (Dam Safety Action Classification) depicts the degree of urgency
of safety-related actions. IRRMs (Interim Risk Reduction Measures) are formulated and undertaken for dams
not considered tolerably safe until more permanent remediation measures are implemented. SOURCE:
USACE (2011b).
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Current Dam and Levee Infrastructure, Management, and Governance
Defining legislation is emerging only recently, and is limited to the requirement to create
a National Committee on Levee Safety and a proposal for a national levee safety program.
Levee safety has been a concern for most of the last century, but other than individual
federal-agency programs and state-level initiatives, efforts have been ad hoc. Although
intended only to be a requirement for the NFIP,21 the NFIP 100-year flood—rather than
hydrograph shape and duration—has become a de facto national standard. The 100-year
water elevation now serves as a baseline for many levee applications.
The 2005 authorization of the NLD and the 2007 Water Resources Development/
National Levee Safety Act have placed levee safety in phase with where dam safety was
in the 1980s.22 These steps constitute an initial legal and policy scaffold from which levee
safety can be designed and constructed into a nationally consistent and rigorous effort
(given the appropriate attention and resources). It will be crucial to bring diverse com-
munity members and stakeholders together to create a uniform structure for management
and technical decision making. An important development will be the application of risk
assessment.23 The NCLS (2009) has submitted a report and recommendations for policy
and organization for a national levee safety program, but its recommendations remain under
consideration (as of this writing).
The current Economic and Environmental Principles and Guidelines for Water and
Related Land Resources Implementation Studies (P&G) are the fundamental policies
that govern how federal agencies evaluate proposed water resource development projects,
emphasizing national economic benefits as the primary criterion for project justification
( WRC, 1983). The secretary of the Army was tasked with updating the P&G under the
Water Resources Development Act (WRDA) of 2007.24 The Obama Administration is
expanding the scope of the P&G to include all federal water resources agencies.25
Major responsibilities in levee safety rest with FEMA and USACE and in some cases
with the states. FEMA administers the NFIP, through which it defines its responsibilities
related to levees, particularly regarding levee accreditation and mapping areas protected by
levees. FEMA is examining the impact of levee mapping on the NFIP, initiatives such as
the Map Modernization program26 (which, among other things, establishes criteria for levee
accreditation), and is examining risk-based approaches. FEMA also cochairs the National
Committee on Levee Safety. USACE is responsible for the 14,700 miles of levees it has
constructed, operates, and maintains, as well as levees it has constructed but are oper-
ated and maintained by others, and levees included in the Rehabilitation and Inspection
See a www.fema.gov/business/nfip/.
21
See 140.194.146.135/LeveeSafety/Documents/timeline.pdf.
22
Some states are developing new flood hazard criteria. California, for example, has a draft standard in place for using
23
the 200-year return-period peak flood as its design criterion for urban and urbanizing areas (CA DWR, 2012b).
See www.gpo.gov/fdsys/pkg/PLAW-110publ114/content-detail.html.
24
See www.whitehouse.gov/administration/eop/ceq/initiatives/PandG.
25
See www.fema.gov/plan/prevent/fhm/mm_main.shtm (accessed February 8, 2012).
26
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
Program (per Public Law 84-99).27 The Secretary of the Army is responsible for carrying
out activities of the new National Levee Safety Program Act.28 The USACE Director of
Civil Works chairs the NCLS tasked with developing policy and recommendations for a
National Levee Safety Program under that act. Their report, delivered in January 2009
remains under review by the Office of Management and Budget and, as of the writing of
this report, the recommendations remain unaddressed.29 Other federal agencies, including
the Department of Interior (DOI) and U.S. Department of Agriculture, have roles in levee
safety. The DOI Bureau of Reclamation manages some levees associated with water supply
and flood control projects and oversees levees associated with some irrigation projects that
are owned and operated by others. The USDA Natural Resources Conservation Service
designs levees to provide protection to support agricultural use of land (ILPRC, 2006).
Table 3.4 summarizes guidance and standards for levee safety. As for dam-related
guidance, these are technical in nature and support governance by informing decisions.
An important technical issue affecting governance is standards related to the extent that
hazards affect design and operation. For example, USACE standards for levee design were
once based on the Standard Project Flood (SPF), a flood that can be expected from the
most severe combination of meteorologic and hydrologic conditions considered reasonably
characteristic of the region. The SPF was often considered to be equivalent to a 300-year
(or more) return-period event when plotted on an extrapolated flood-frequency curve for
the location (USACE, 1965, 2006). With the acceptance of a 100-year peak flood as the
standard in accordance with the NFIP, the design criterion was effectively changed (e.g.,
from a 300-year to a 100-year return period). More recently, USACE has been moving to
risk-based design, creating a new design paradigm for the United States (USACE, 2011b).
FEMA is considering incorporating risk-based standards into the NFIP; this would con-
stitute a major shift in design guidance and standards for levees (see Box 3.6).
Given the lack of national policy, guidance, or standards for states, NFIP criteria influ-
ence management decisions via local government or community initiatives established to
qualify for flood insurance. But as stated earlier, few states keep lists of levees within their
borders, and about half the states have no formal authority or program at the state level for
levee safety or inspection programs (as of 2006).30 Fewer than one-third of states have even
modest safety programs, whose implementation is often delegated to local authorities or
programs, and only about 20 percent of the states have relatively comprehensive authori-
ties and programs. Management of levees in some states is through levee boards or similar
organizations. Levee boards in Louisiana, for example, are managed through the Depart-
ment of Transportation and Development and consist of community members appointed
See www.saj.usace.army.mil/Divisions/Operations/Branches/EmergencyMgt/programs_RIP.htm.
27
See uscode.house.gov/download/pls/33C46.txt.
28
See www.leveesafety.org/faq_committee.cfm.
29
M. Ogden, ASDSO, personal communication, September 7, 2011.
30
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Current Dam and Levee Infrastructure, Management, and Governance
TABLE 3.4 Levee-Safety Governance-Related Guidance and Standards
Date Responsible Organization Publication
October 2010 U.S. Army Corps of Engineers Proceedings of the Workshop, “Exploration of
(USACE) Tolerable Risk Guidelines for the USACE Levee
Safety Program,” Institute for Water Resources
Report 10-R-8
April 2009 USACE ETL 1110-2-571, Guidelines for Landscape
Planting and Vegetation Management at
Levees, Floodwalls, Embankment Dams, and
Appurtenant Structures
October 2008 State of California Draft Interim Levee Design Criteria for Urban
and Urbanizing Areas (200-year protection
by 2015)
April 2000 USACE EM 1110-2-1913, Design and Construction
of Levees
May 2005 USACE ETL 1110-2-569, Design Guidance for Levee
Underseepage
August 2010 USACE EC 1110-2-6067, USACE Process for the
NFIP Levee System Evaluation
August 2005 Federal Emergency Procedure Memorandum 34, Interim
Management Agency (FEMA) Guidelines for Studies Including Levees.
Procedure Memorandum 34 Requires Certification Data on Levees
July 2008 FEMA Procedure Procedure Memorandum 43, Guidelines for
Memorandum 43 Identifying Provisionally Accredited Levees.
Removes levee from NFIP if not accredited and
allows provisional accreditation for 2 years
October 2002 44 CFR § 65.10 Section 65.10 of National Flood Insurance
Program Regulations: FEMA guidance on
mapping areas protected by levee systems
(not risk based)
by the governor. Louisiana has a state association of levee boards, ostensibly to coordinate
activities of all Louisiana levee boards.31 Of formal state levee-safety programs, California’s,
in its Department of Water Resources, appears to be the most advanced (see Box 3.7).
See www.albl.org (accessed February 8, 2012).
31
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DAM AND LEVEE SAFETY AND COMMMUNITY RESILIENCE
BOX 3.6
Uncertainty in Hazard Characterization
The uncertainty in hazard characterization is increasingly recognized in applying risk-based procedures
(and setting policy related to their use). Calculations of the frequency of flood events, for example, are im-
proved with larger, accurate, and complete historical-event databases. The greater the number and accuracy
of events in the database, the smaller the uncertainty in the estimate of the frequency of future events. This
can be demonstrated through the calculation of return-period frequency of hurricanes in the Gulf of Mexico.
Hurricane return-period calculations have long been based on the atmospheric pressure at the hurricane
center (its central pressure). Table 1 illustrates the change in estimated return period for a storm like Katrina,
given the size of the historical-event database. The return period of a hurricane with a central pressure and
maximum wind speeds similar to those of Hurricane Katrina would have been calculated at 900 years by
using the historical database as of 1959, but at only at 98 years on the basis of the historical record as of
2005 (Irish et al., 2008). In addition, the use of central pressure alone, as was previously done, is not ad-
equate to characterize the surge generation potential of a hurricane. It is necessary to consider both central
pressure (storm intensity) and radius to maximum winds (physical size) of the storm to represent its ability
to generate storm surge. Therefore, using the Saffir-Simpson Scale (representing the intensity of sustained
winds) as a basis of characterizing return period relevant to surge levels is inadequate.
In the 1960s, the levee systems for hurricane protection around New Orleans were designed according
to the USACE criteria that, at the time, were thought to accommodate a 200- to 300-year event. The uncer-
tainty analysis conducted by IPET (2009) as a component of the risk assessment of the levee and floodwall
systems in place during Katrina estimated that the system had a mean failure period of 40–50 years (caused
by catastrophic breaching, given the 2005 knowledge base of hurricane hazards in the gulf).
TABLE 1 Variability of Return Period of Hurricane Hazard in Gulf of Mexico
Publication (Year) and Period of Record
Meteorological U.S. Weather Bureau National Weather National Oceanic and
Parameter Tech Report 33 (1959) Service Tech Report 23 Atmospheric Administration
1900–1956 (1979) 1900–1975 and National Climatic Data
Center Preliminary Analysis
(2006) 1900–2005
100-year central 934.6 926.2 901.7
pressure index
(millibars)
100-year 1,013.2 1,008.1 1,007.9
peripheral pressure
(millibars)
Return period for a 900 285 98
storm of Hurricane
Katrina intensity (905
mb) (years)
SOURCE: IPET, (2007a, 2009).
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Current Dam and Levee Infrastructure, Management, and Governance
BOX 3.7
Levee Safety in California
California has a highly developed levee safety program. The Division of Water Management in the
California Department of Water Resources (DWR) was established in 1977 and is divided into five offices
responsible for forecasting, integrated environmental stewardship and flood management, design and con-
struction of flood control projects, rehabilitation of California system levees, and operation and maintenance
of federally constructed flood control structures.a The California FloodSAFE initiative, formulated in 2007,
is aimed at more effective floodplain management, risk reduction, and development of a comprehensive,
systemwide flood management plan for the Central Valley of California.
A major tenet of the FloodSAFE initiative is to require that building codes include flood damage-reduction
measures for the estimated 200-year floodplain.b This applies to areas protected by facilities of the Central
Valley Flood Protection Plan where flood depths exceed 3 ft for the 200-year flood event (0.5 percent annual
chance of flood). Code updates are planned in cycles and include such measures as requiring flood evacua-
tion locations to be above the 200-year water-surface elevation, and requiring that flood vents be designed
to reduce the potential for structural collapse (by reducing hydrostatic differential on walls).c FloodSAFE
also includes preparation of 200-year flood inundation-area maps and flood information for owners and
residents. The program is the focal point of the Division of Flood Management in the DWR. Resources in the
DWR have been divided into seven “functional areas” as depicted in the figure to prepare for implementation
of the program. Limited financial resources will be the major challenge for full implementation of FloodSAFE.
Organization and alignment of DWR resources to prepare for the implementation of the DWR FloodSAFE initiative. SOURCE:
CA DWR (2012a).
See www.water.ca.gov/floodmgmt/ (accessed March 8, 2012).
a
See www.ca.gov/floodsafe/ (accessed March Box 3-7 new
8, 2012).
b
See www.water.ca.gov/BuildingCod (accessedBitmapped
March 8, 2012).
c
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