About Dams

There are more than 90,000 dams across the U.S., each designed and built differently to provide important services to communities.

Dams are uilt across a river or body of water to hold, divert, or regulate water to manage flooding, provide power, water, and space for wildlife and recreation, and to support navigation.

To learn more about dams, how they work, and where they’re located throughout the U.S., visit the National Inventory of Dams at https://nid.sec.usace.army.mil/#/dam-basics/what-is-a-dam.

Announcements

New Low-head Dam Inventory

A low-head dam is a “river-wide artificial barrier that generally spans a stream channel, blocking the waterway and creating a backup of water behind the barrier, with a drop off over the wall of not less than six inches and no more than 25 feet,” as defined in the Water Resources and Development Act of 2024. Many low-head dams are also called “run-of-river dams” because the water flows over the top of the dam.

Typically, these dams have not been included in publicly available datasets. In Fall 2025, the U.S. Army Corps of Engineers will publish an initial dataset that can be viewed within the National Inventory of Dams. The site will also include new educational resources. To learn more, visit

https://nid.sec.usace.army.mil/.