October 2016 - The 2016 National Inventory of Dams (NID) database is now available! All charts, queries and maps reflect the most current NID database. The NID was populated using the 114th Congressional District information. State and federal dam regulators provided their data from August 2015 to January 2016 for inclusion in the 2016 database. Please be aware that inspection and EAP dates reflect 2015 data, so any inspections or updates since then will not be reflected in the current NID. Please contact the respective state or federal regulatory authority for the most up-to-date information.

April 2015 - Non-government users no longer need a user name and password to access the NID database. Government users, however, must still obtain a user name and password should they need access beyond the public site to accomplish their official duties. All previous accounts have been deleted and new accounts will need to be re-established.

Welcome to the National Inventory of Dams Web Site. Non-government users can query the database using the interactive report and map functions but cannot directly download any data from this site.

Congress first authorized the U.S. Army Corps of Engineers to inventory dams in the United States with the National Dam Inspection Act (Public Law 92-367) of 1972. The NID was first published in 1975, with a few updates as resources permitted over the next ten years. The Water Resources Development Act of 1986 (P.L. 99-662) authorized the Corps to maintain and periodically publish an updated NID, with re-authorization and a dedicated funding source provided under the Water Resources Development Act of 1996 (P.L. 104-3). The Corps also began close collaboration with the Federal Emergency Management Agency (FEMA) and state regulatory offices to obtain more accurate and complete information. The National Dam Safety and Security Act of 2002 (P.L. 107-310) and the Dam Safety Act of 2006 reauthorized the National Dam Safety Program and included the maintenance and update of the NID by the Corps. Most recently, the NID was reauthorized as part of the Water Resources Reform and Development Act of 2014.

The NID consists of dams meeting at least one of the following criteria;
1) High hazard potential classification - loss of human life is likely if the dam fails,
2) Significant hazard potential classification - no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns,
3) Equal or exceed 25 feet in height and exceed 15 acre-feet in storage,
4) Equal or exceed 50 acre-feet storage and exceed 6 feet in height.

The goal of the NID is to include all dams in the United States that meet these criteria, yet in reality, is limited to information that can be gathered and properly interpreted with the given funding. The NID initially consisted of approximately 45,000 dams, which were gathered from extensive record searches and some feature extraction from aerial imagery. Since continued and methodical updates have been conducted, data collection has been focused on the most reliable data sources, which are the many federal and state government dam construction and regulation offices. In most cases, dams within the NID criteria are regulated (construction permit, inspection, and/or enforcement) by federal or state agencies, who have basic information on the dams within their jurisdiction. Therein lies the biggest challenge, and most of the effort to maintain the NID; periodic collection of dam characteristics from 49 states (Alabama currently has no dam safety legislation or formal dam safety program), Puerto Rico, and 18 federal offices. The Corps resolves duplicative and conflicting data from the 68 data sources, which helps obtain the more complete, accurate, and updated NID. The NID is published every two years.

If you have any issues or questions, please contact the NID Data Team at