link to page 1 
May 22, 2023
Nonfederal Levee Safety: Primer, Status, and Considerations
This In Focus discusses nonfederal levees, the evolution of
construction, operation, and maintenance by eliminating
federal efforts to enhance nonfederal levee safety since
flood insurance purchase requirements and reducing
2007, and related policy considerations.
premiums for structures that are mapped as removed from
the 100-year floodplain due to a levee. The Federal
Nonfederal Levees and Risk
Emergency Management Agency (FEMA) is responsible
Levees (i.e., engineered earthen embankments) and
for accrediting levees to appear on NFIP Flood Insurance
floodwalls (i.e., metal or concrete flood control structures)
Rate Maps (FIRMs). To be accredited and appear on a
are built to reduce flood losses. Herein, these structures are
FIRM, the levee owner must obtain a certification
collectively referred to as levees. Levees currently operated
consisting of documentation, signed and sealed by a
and maintained by nonfederal entities may have been
registered professional engineer, that the levee meets the
constructed by federal agencies (e.g., U.S. Army Corps of
NFIP requirements at 44 C.F.R. §65.10.
Engineers [USACE]); with federal government assistance;
or by state, local, or private entities. There may be as many
USACE Repairs and Inspections
as 100,000 miles of nonfederal levees in the United States.
USACE operates a repair program—the P.L. 84-99
Rehabilitation Program—for nonfederal flood control
While levees are built to reduce risk, they also can pose
works. If a nonfederal levee owner participating in the
risks. Residual risk remains after a levee is constructed. For
program has maintained a levee in good condition, as
example, floods more intense than the flood that a levee
inspected and assessed by USACE, USACE can repair
was designed to manage can overtop the levee, or poorly
damage to that levee from certain floods or other natural
designed, constructed, or maintained levees can fail in other
events. USACE regularly inspects 1,600 nonfederal levee
ways. Risk associated with levees is a function of the
systems (consisting of 13,000 miles of levees) that
hazard (e.g., level and duration of floodwaters), the levee’s
participate in the program.
performance, and the potential consequences (i.e., what
assets and populations may be exposed to loss, damage, and
National Levee Safety Program
disruption). Figure 1 illustrates the components of levee
Prior to 2007, there was no federal authority to inventory
risk and some levee performance concerns. Levee safety
levees or promote state and tribal levee safety programs.
concerns increase when development behind a levee
Beyond federal requirements to appear on an NFIP map and
increases.
to participate in the P.L. 84-99 Rehabilitation Program,
there also was no broadly applicable national standard or
Nonfederal or private entities that operate levees are
requirement for nonfederal levee construction or
responsible for levee maintenance and safety. While a state
maintenance. In 2007 and 2014, Congress authorized the
may choose to regulate levees, only a few states currently
National Levee Safety Program (NLSP; 33 U.S.C. Chapter
operate programs to oversee design, construction, and
46), consisting of multiple program elements, including the
maintenance of nonfederal levees. There is no federal
creation of a levee inventory, development of voluntary
authority to regulate nonfederal levee safety, although some
safety guidelines, and the promotion of state and tribal
federal programs may shape how nonfederal levees are
levee safety programs. Congress charged USACE with
constructed and maintained.
developing the inventory—the National Levee Database
(NLD). The NLD currently captures almost 25,000 miles of
Federal Flood Insurance and Levees
levees and is the most complete dataset on the nation’s
Since its establishment in 1968, the National Flood
levees, although it is not comprehensive. Many NLSP
Insurance Program (NFIP) has indirectly encouraged levee
actions beyond the NLD have remained largely unfunded.
Figure 1. Illustration of Levee Risk Components and Levee Performance Concerns
Source: CRS, adapted from Zina Deretsky, National Science Foundation, and USACE, Risk Assessment for Flood Risk Management Studies, 2017.
https://crsreports.congress.gov
Nonfederal Levee Safety: Primer, Status, and Considerations
methodologies for determining probable maximum floods
Figure 2. Levees in the National Levee Database
and approaches for considering changing climate conditions
over the functional life of a levee system. Among the levee
safety policy questions raised is how levee investments
should proceed in light of data limitations. Other policy
questions include how to integrate new levees and the
rehabilitation of existing levees into more comprehensive
water and flood-risk management systems that work
compatibly with natural features and floodplain functions.
There also is the question of the efficacy of nonfederal
efforts to manage land use and residual risk behind levees
and federal efforts to encourage such management.
Levee safety stakeholders are watching whether new
programs will support nonfederal levee safety investments.
For example, the Safeguarding Tomorrow Through
Ongoing Risk Mitigation Act of 2020 (P.L. 116-284)
Source: CRS using National Levee Database, 2023.
authorized FEMA to enter into agreements with eligible
Notes: Levees in red are USACE-owned or in the P.L. 84-99
entities to establish revolving loan funds for hazard
Rehabilitation Program; other levees are in purple.
mitigation. USACE’s Corps Water Infrastructure Financing
Program also has been authorized to provide loans for flood
While most states and tribes have not materially advanced
control projects, which could include levees. However,
their levee safety programs or levee construction and
current congressional appropriations limits on the
program’s implementation restrict lending to nonfederal
maintenance oversight since 2007, some states have
advanced and contributed to NLD efforts, such as
dam safety-related projects (see CRS Insight IN12021,
California, Illinois, Ohio, Pennsylvania, and Texas. In
Corps Water Infrastructure Financing Program (CWIFP)).
2022, pursuant to the NLSP, USACE and FEMA kicked off
a multiyear effort to develop voluntary national levee safety
USACE also may complete a P.L. 84-99 Rehabilitation
guidelines and to provide tools for states and tribes to
Program rulemaking in 2023. Among other actions, the
establish and implement their own levee safety programs.
November 2022 proposed rule (87 Federal Register 68386)
would change the cost sharing for some of the program’s
Other Nonfederal Levee Activities
repairs from between 80% and 100% federal to 65%
Congressional direction in 2012 and 2014 led to efforts by
federal.
FEMA and USACE to better coordinate their data sharing
on levees and levee inspections to assist with FEMA levee
Congress may conduct oversight of NLSP implementation,
accreditation. Congressional direction also led to FEMA
how nonfederal levee safety is being addressed through new
altering how levees appear on FIRMs. Levees are shown on
and existing federal assistance programs, and how agencies
FIRMs, but legislation to require that the maps identify
are implementing long-standing programs. While
residual risk behind levees has not been enacted.
nonfederal levee data are provided voluntarily to the NLD,
NLD data may be used by federal agencies for statutory or
In a 2018 report on levee safety, USACE estimated the cost
regulatory purposes. For example, the new pricing
to address safety issues for federally constructed levees and
methodology introduced by the NFIP, known as Risk
levees in the P.L. 84-99 Rehabilitation Program at between
Rating 2.0, relies on the NLD to determine the level of risk
$6.5 billion and $38 billion (2018 dollars). As described in
reduction that a levee provides. See CRS Insight IN11777,
CRS Report R47286, Flooding: Selected Federal
National Flood Insurance Program Risk Rating 2.0:
Assistance and Programs to Reduce Risk, nonfederal levee-
Frequently Asked Questions. Data from the NLD is used in
related improvements may be pursued under various federal
the calculation of flood insurance premiums for individual
assistance programs. These opportunities have expanded in
structures behind levees. However, only 20% of levees in
recent years due to new programs (e.g., FEMA’s Building
the NLD have enough information to fulfill all key data
Resilient Infrastructure and Communities program [BRIC])
needs for NFIP pricing, adding to congressional concern
and existing programs receiving additional funding through
about changes in premiums under Risk Rating 2.0. Several
infrastructure and disaster supplemental appropriations
Louisiana parishes are suing FEMA over concerns that Risk
legislation. In its first two years (FY2020-FY2021), BRIC
Rating 2.0 does not properly account for flood control
funded seven levee projects.
measures such as levees.
Policy Considerations and Other
Nicole T. Carter, Specialist in Natural Resources Policy
Developments
Diane P. Horn, Specialist in Flood Insurance and
Entities currently investing in new levees and levee
Emergency Management
improvements are confronted in the near term with certain
data limitations. While some historic precipitation data has
IF12404
been updated in recent years, efforts are ongoing to update
https://crsreports.congress.gov
Nonfederal Levee Safety: Primer, Status, and Considerations
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.
https://crsreports.congress.gov | IF12404 · VERSION 1 · NEW