Aquatic Organism Passage (AOP) in Culvert Design

Aquatic Organism Passage Design: Four Years of Experience with HEC26

  • Roger Kilgore (Kilgore Consulting and Management)
  • Scott Hogan (FHWA Resource Center)
  • Bart Bergendahl (Federal Lands Highway Division)


The Federal Highway Administration released Hydraulic Engineering Circular (HEC) 26 “Culvert Design for Aquatic Organism Passage” in October 2010 to provide and engineering based stream simulation method for designing culverts to promote fish passage. The basis is to provide hydraulic conditions within an embedded culvert similar to those found upstream and downstream of the culvert over a wide range of flow rates. By simulating the depth, velocity, and sediment transport capabilities of the channel through the culvert, it is reasonable to infer that fish capable of passing up and down the channel can also pass through the culvert. Species-specific information on swimming capabilities or behaviors is not required.

In the period since its release, FHWA and others have gained experience in the design and performance of these structures. This presentation provides brief background information on the methodology, but focuses on the experience with the method since its introduction. Case examples are presented along with challenges designers faced with the methodology. Areas for potential additional guidance are also discussed.

How to Cite:

Kilgore, R. & Hogan, S. & Bergendahl, B., (2014) “Aquatic Organism Passage Design: Four Years of Experience with HEC26”, National Hydraulic Engineering Conference 2014 1(2014).

Rights: Copyright © 2014, Roger Kilgore, Scott Hogan, and Bart Bergendahl

Publisher Notes

  • Panel moderated by Bart Bergendahl, FHWA.
  • About the Presenters: Mr. Kilgore is a Professional Engineer with 30 years of experience in hydrology and hydraulics, stormwater management, water quality, and flood mitigation. He is Principal of Kilgore Consulting and Management, which he founded in February of 2000. Mr. Kilgore has been active in the planning and design fields and has also written or contributed to several design manuals including Highway Hydrology (HDS 2), Hydraulic Design of Energy Dissipators for Culverts and Channels (HEC 14), Design of Roadside Channels with Flexible Linings (HEC 15), Urban Drainage Design Manual (HEC 22), and Culvert Design for Aquatic Organism Passage (HEC 26). He has also been active in research as the project management for support services at the Turner Fairbank Highway Research Center Hydraulics Laboratory for several years and Principal Investigator for an NCHRP study on coincident flooding. He is a project manager/senior engineer for the Central Federal Lands Highway Division of the FHWA with responsibilities for bridge and culvert hydraulics, roadway drainage, erosion control, and water quality. Mr. Kilgore is a trainer and/or developer for NHI courses in hydrology, hydraulics software, and coastal engineering.

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Published on
20 Aug 2014
Peer Reviewed