Culvert Design for Fish Passage 2 - Advanced Topics

Installation of a culvert to carry a small stream under a roadway is a very common practice. However, culverts quite often function as a barrier to fish, isolating them from important habitat areas. Proper design of culverts considers length, slope and flow velocity of the culvert and fish species and size. This 3-hour online course is the second of a two-part series on culvert design for fish passage. This course covers channel profile impacts, modifying structures, tide and flood gates, fishways, baffles andthe design of roughened channels.

Extensive research on design has been conducted in the state of Washington and serves as the basis for this course. The primary species of concern in Washington are salmon and trout. While the guidance was written specific to Washington, the vast majority of the guidance is applicable to any location where fish passage through culverts is required and much of the guidance applies to all species of fish, not just salmon and trout. Much of the early work in fish passage through culverts focused on swimming speeds of fish species vs. velocities in the culvert. This recent work addresses that issue but goes significantly beyond swimming speeds to identify other design approaches that work better and provide passage for fish other than the target species and size.

At the conclusion of the course, you will have a better understanding of:

• How the channel profile impacts fish passage, including the impacts of headcuts and regrading the channel
• The different types of structures that can be used to modify the channel profile, including log sills, plank controls and boulder controls
• The different types of tide gates and flood gates, how they impact fish passage and how the designs can be modified to improve the potential for fish passage
• The basic types of fishways
• The hydraulics of baffles
• How to design roughened channels, including bed stability and fish passage velocity