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Bridges & Structures

Aquatic Organism Passage (AOP)

New On June 25, 2024, FHWA announced the availability of at least $196 million for FY2023 Culvert AOP grants as part of the FY23-26 Culvert AOP NOFO. The deadline to apply for FY23 funding via Grants.gov is Monday, September 23, 2024, at 11:59 p.m., EDT. Learn more about the Culvert AOP Grants.


Culvert AOP Program logo

Where transportation systems such as roads and tracks intersect waterways, a result may create barriers that impede the passage and impair the habitat of aquatic organisms and other wildlife. The Federal Highway Administration (FHWA), an agency within the U.S. Department of Transportation (USDOT), promotes approaches to reduce or remove barriers to passage of both aquatic and wildlife species where they interact with our Nation’s transportation system. The FHWA also recognizes that removing these barriers may have flood risk reduction, environmental, cultural, and societal benefits. Aquatic organism populations may be critical to local economies and Native and Tribal communities.

The FHWA is working to advance the state of water crossing design practice for aquatic organism passage (AOP). Through these advances, the FHWA seeks to encourage practices that minimize negative effects on fish and other aquatic organism populations while creating safer and more resilient structures.

The three links below provide some background (“What is AOP”), information on AOP Grants (“Grants”) and a variety of resources related to both aquatic organism passage and related topics (“Resources”). Click on any of the icons to proceed to a specific topic.

Updated: 06/25/2024
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000