Environment, Landscapes, Interpretation

By: Watershed Admin | 0 Comments

Stream Simulation can prevent culvert washouts - and makes fish happy!

Remember Hurricane Irene that made national headlines in 2011? The flood destroyed more than 500 road miles and 200 bridges and culverts, and harmed much aquatic life. Interestingly, culverts that had been recently replaced using the Stream Simulation Design Approach suffered no damage and safely passed huge volumes of water, gravel and trees that clogged and destroyed other traditional culverts in the area.

Designing the right type and size of culvert is important to prevent future road collapses at poorly designed culvert crossing sites. Stream simulation is now more popular than traditional culvert design because of its bottomless structure. This structure provides a wider opening and is preferred by fish for its natural subgrade condition. Safe and stable stream crossings can accommodate wildlife and protect stream health while reducing expensive erosion and structural damage.

The Stream Simulation Design is used to create or maintain natural stream processes in a culvert. It is based on the principle that if fish can migrate through a natural channel, they can also migrate through a man-made channel that simulates the stream channel.

Stream simulation channels are designed to adjust laterally and vertically to a wide range of floods and handle a variety of gravel and wood without inhibiting fish and other aquatic organisms from moving up or downstream.  While initial installation costs range from 30 to 70 percent more than traditional culvert approaches, long term costs are significantly reduced as the culverts survive large floods and function virtually maintenance free.

The Watershed Company is currently partnered with County staff to use the stream simulation approach for ten culvert replacements in Skagit County to help communities avoid future flooding threats and ensure habitat protection and public safety. Get in touch if you'd like help with your culvert replacement!

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