Levees / Sources
Sources and method
Everything on this site is compiled from public federal records. No figure is estimated, interpolated or supplied from any other source.
Where the data comes from
| Source | Used for | Licence |
|---|---|---|
| USACE National Levee Database | Every system record: name, location, condition and accreditation status, population and structures in the leveed area, length, sponsor and USACE hierarchy. | US federal work, public domain |
| FEMA National Flood Hazard Layer | Flood hazard mapping context. Distributed as county and state GIS packages rather than as a per-address service. | US federal work, public domain |
How it is presented
A missing value is shown as missing
Roughly half the fields on a given system are unpopulated in the federal record. Where USACE has not published a value, the page says Not published. It does not print a zero, a dash, or an estimate, and it does not drop the row. The difference between an absent figure and a zero is the difference between two completely different facts.
Totals count only what exists
State, county and national totals are summed across the systems that publish a figure, and each page states how many that was. Of 7,626 current systems, 7,183 publish a population figure.
Archived records are separated
3 records are marked archived in the source. Each keeps its page and carries a notice, and none is included in any total. Why that matters.
Ratings are reproduced, never translated
Accreditation status, screening ratings and inspection ratings appear exactly as published. This site does not score, rank, grade or colour-code levee systems, and it does not describe any system as safe or unsafe.
No statement is made about a property
Accreditation describes a system measured against a design flood event. It says nothing about whether a particular address will flood, and USACE notes the database may not represent the totality of levees in the United States. Questions about a specific property belong with a local floodplain administrator.
Refresh
Last refreshed 2026-09-10. USACE updates the register irregularly and publishes no change feed, so this site re-reads the source on a weekly schedule and compares every field against the previous read. Where a value has changed, the change is reviewed before it is published rather than being written straight through. How to judge the age of a page.
Found something wrong?
Corrections are checked against the source record and dated on the page. Write to corrections@levees.com with the system name or ID and the field in question.