US Army Corps of Engineers
Sacramento District Website

Frequently Asked Questions

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The National Levee Database (NLD) is the focal point for comprehensive information about our nation's levees. The NLD provides information about the location and condition of levees across the nation, displayed in an easy-to-use map interface. The database contains information to facilitate and link activities, such as flood risk communication, levee system inspections, and risk assessments, flood plain management, and levee system evaluation for the National Flood Insurance Program (NFIP).

The NLD contains information about the condition and risk information for the 2,000 levee systems (approximately 15,000 miles) that are associated with USACE programs.  An additional 6,000 levee systems (approximately 15,000 miles) have location information, but little to no information about condition and risk. One of the goals for the NLD is to include data about levees owned and operated by all other federal agencies, tribes, states, municipalities, levee boards, and private entities. This information will be added as it becomes available.

 

Risk is a tool that is used to understand and communicate the probability (or likelihood) and consequence of uncertain future events. There are three components of flood risk: hazard, performance, and consequence.

(1) Hazards. Hazards are events that cause the potential for an adverse consequence (e.g. flooding). Typically, the hazards considered in levee safety are potential flooding sources and seismic hazards. Risk enables an understanding of the likelihood of possible hazards and how they may change over time.

(2) Performance. Risk provides a framework for consistently evaluating the probability (or likelihood) of how the levee system is anticipated to function given possible hazards. This is done through considering a combination of past performance, existing conditions, maintenance, and how the existing levee compares to current engineering standards. How the levee is expected to perform may change over time based on the current understanding of industry best practices for levee design and operation despite unchanging levee conditions.

(3) Consequence. Consequences are the effect or outcome resulting from the combination of the hazards and performance. In order to provide a complete picture of the risk and to facilitate more informed decisions, consequences are included in the risk discussion. Potential consequences can also be used to show the benefits provided by a levee system. Consequences may include estimates of potential impacts to life, property, environment, or navigation. All consequences should be considered to inform responsible and transparent decisions.

Information on the latest USACE inspection can be found in the National Levee Database.

Additionally, the California Department of Water Resources routinely inspects federally authorized levees that are sponsored by the Central Valley Flood Protection Board. Inspections are performed in the summer and fall of each year to verify and document maintenance performed by the local maintaining agencies. The state posts the information related to those inspections on their website here: http://cdec.water.ca.gov/fsir.html

The inspection report in its entirety is “For Official Use Only”. We must constantly balance the information stakeholders use to make risk-informed decisions about public safety and safeguarding information that could be used to threaten a project’s security and increase risk of harm to residents.  Knowing and understanding the system is unacceptable or minimally acceptable, without releasing specific vulnerability information in an uncontrolled manner still allows stakeholders and residents to make informed decisions about their personal safety.  Examples include having an emergency evacuation plan and/or purchasing flood insurance to protect economic losses.

Operation, maintenance, repair, rehabilitation and replacement (OMRR&R) activities are local sponsor responsibilities.  The inspection identifies components and features that require monitoring or maintenance actions over time, such as erosion, settlement, vegetation and seepage. Local sponsors have the difficult task of prioritizing the deficiencies found during the inspection and repairing them in compliance with the OMRR&R manual.  We encourage our sponsors to consider addressing deficiencies in a worst-first manner to help reduce as much of the risk as quickly as possible.

 

The Levee Safety Action Classification (LSAC) is one of the many tools we use to better inform our stakeholders and residents of the risk in their communities.

The LSAC is neither a levee rating nor grade, it is a classification system designed to take into account the probability of the levees being loaded (Hazard), existing condition of the levee, the current and future maintenance of the levee (Performance), and the Consequences if a levee were to fail or be overwhelmed.

There are five action classes used in the USACE Levee Safety Program ranging from “Very Low” to “Very High”. The LSAC does not communicate risk in and by itself but should be used as the framework to discuss risk associated with levee systems and to drive actions to reduce risk. Information on the LSAC for specific levee systems can be found on the National Levee Database.

The LSAC does not affect PL 84-99 eligibility, and does not directly affect the FEMA accreditation of the levee system.

 

Levees can regain active status once an Acceptable or Minimally Acceptable rating is received on a levee inspection.

Alternatively, USACE offers sponsors a process through the system-wide improvement framework (SWIF) program to remain temporarily eligible for PL 84-99 assistance while they correct unacceptable deficiencies as part of a broader, system-wide improvement to their levee systems. Enrollment in the program is a two-step process; sponsors submit a Letter of Intent, followed by submission of a SWIF plan. The applicant has up to two years to develop the SWIF plan. A system can regain active status upon USACE approval of the sponsor’s Letter of Intent to develop a SWIF plan.