Data Sources & Methodology

Last updated: March 7, 2026

About Our Data

DamIndex organizes public U.S. dam records from the Army Corps of Engineers' National Inventory of Dams (NID) into a searchable database for research and educational use. We standardize location, ownership, and classification fields to help users compare records across states and agencies.

Primary Data Source

All dam records on this site come from the National Inventory of Dams (NID), a database maintained by the U.S. Army Corps of Engineers (USACE) in cooperation with state dam safety programs and federal agencies.

The NID contains records for more than 92,000 dams across the United States and its territories. It is the most comprehensive public dataset on U.S. dam infrastructure, covering physical characteristics, hazard classifications, inspection records, ownership, and purpose information.

Official source: National Inventory of Dams (nid.sec.usace.army.mil)

Maintained by: U.S. Army Corps of Engineers

Data license: Public domain (U.S. government work)

How We Process the Data

We import the NID's full national CSV dataset and process it through several standardization steps:

  • Location normalization: State codes, county names, and coordinates are validated and standardized for consistent geographic browsing.
  • Classification mapping: Hazard potential levels, dam types, and owner categories are mapped to consistent labels for easy filtering and comparison.
  • Purpose extraction: Multi-purpose dams have their individual purposes separated and linked for better searchability.
  • Unit formatting: Heights, lengths, storage volumes, and other measurements are formatted with appropriate units for readability.
  • SEO optimization: Each dam record is assigned descriptive titles and summaries to help users find relevant information through search engines.

Update Frequency

We sync our database with the latest available NID data on a quarterly basis. The NID itself is updated periodically by USACE and participating state agencies. Due to the nature of the original dataset, there may be a lag between changes in the field and their reflection in our records.

Important Disclaimer

DamIndex is an independent project and is not affiliated with, endorsed by, or connected to the U.S. Army Corps of Engineers, the Federal Emergency Management Agency (FEMA), or any state dam safety program. The data presented here is provided for informational and educational purposes only. Dam conditions may have changed since the last data update. Do not use this information for emergency planning or safety decisions.

Questions About Our Data

If you have questions about how we process or present dam data, or if you notice an error in a record, please contact us. We are committed to accuracy and transparency.