U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Bridges & Structures



Culvert Design for Aquatic Organism Passage

HEC-26 presents a stream simulation design procedure, methods, and best practices for designing roadway culverts to facilitate aquatic organism passage (AOP). Fish species have been the focus of most AOP efforts over the years and much has been learned about fish specifically. Therefore, many of the references to AOP in this manual derive directly from what is known about fish passage. However, recognizing that many other organisms also transverse stream crossings, the FHWA intends HEC-26 to encompass the broader scope of general AOP.

HEC-26 is not intended to conflict with, replace, or override accepted AOP guidance and procedures adopted in particular locations. The FHWA intends to update future HEC-26 editions to reflect advances in AOP knowledge and improvement of methods.

HEC-26 presents a bed stability-based approach that accounts for the physical processes related to the natural hydraulic, stream stability, and sediment transport characteristics of a particular stream crossing. The HEC-26 approaches do not require specific information on fish, or other aquatic organisms, but allows incorporation of such information when required.

  • FHWA Publication Number: HIF-11-008
  • Publication Year: 2010

Other documents in this series:

PDF files can be viewed with the Acrobat® Reader®
Word files can be viewed with the Word Viewer
Updated: 10/20/2016
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000

All Federal Highway Administration (FHWA) information technology systems will be unavailable, Friday, October 28, at 10:00 p.m. to Sunday, October 30, at 11:59 p.m., EDT, while work is being performed on the network. During that time, users will not be able to access any FHWA systems.

If you have any questions or problems, please contact the 5-Help Service Center @ (866) 466-5221 or 5-HelpServiceCenter@dot.gov.