What is it?

Rock cross vanes and similar in design and function to rock vortex weirs. The difference between the two structures is that the top level of rock in cross vanes does not contain any spaces. This structure is constructed to direct streamflow and control stream grade. Fish passage should be considered during design cross vanes will not become a barrier. These structures are used in streams with predominantely gravel and cobble substrates.

( photo from Wild Fish Habitat Initiative)

Conservation Benefits

• Creates a downstream scour pool which can be utilizied by fish and other aquatic organisms
• Prevents disruption of sediment transport
• Provides instream habitat for fish and other aquatic organisms
• Reduces streambank erosion and redirects flow to the center of the stream

What does it include?

Rock cross vanes are constructed out of rock. Rock size and placement will depend on stream depth, location in the stream, and baseflow. Footer stones are placed along the bottom of the stream (typically one or two layers) to support the top level of stone (vane stones). Stones should be large enough to not be dislodged in moderate and large storm events.