Cascade Domes recently had a wonderful opportunity to put Dome construction on the back burner and ship off to Summit Lake to construct an amphibian fence before temperatures became too cold. As the name implies, Summit Lake is at fairly high elevations so by the end of the project we were watching the snow creep down.
So what the heck is an amphibian fence and why are we building one? Well at Summit Lake it is all about the Western Toad - a blue listed species suffering a significant highway mortality rate during their yearly migration from breeding ground to hibernation ground. They play a major role in their ecosystem so it is up to us to do our best to protect them from the impacts of highway traffic.
Last year a highway underpass was installed to give the toadlets a safe passage, now the challenge is encouraging the toadlets to make use of it! Two styles of fencing were used for the migration over the summer, the first a pre-cast plastic fence, and the other fabricated from plastic sheets and spikes.
The cascade amphibian fence!
We set out to work on both sides of the culvert and create a concrete fence to guide the toadlets to their crossing. Working in four separate locations allowed us to make use of natural terrain features and develop several areas for toads, who may become caught on the highway side of the fence, to cross. The idea is a "one way" fence and we did our best to achieve the results - next year's migration should let us know how we did.
The fence pictured here is the south portion of the lake side, thanks to an abundance of large rocks we were easily able to establish many "toadlet crossings" to allow the toads to crawl back over the fence should they find themselves on the dangerous highway side. The shotcrete texture creates a featured surface that should be an easy climb for them.
To prevent the toadlets from gaining access to the highway the fence was constructed with a 3.5 inch overhang and a smooth vertical surface. This should be a worthy obstacle to keep toads from the road.
Now, both sides of the culvert have had the plastic replaced with concrete and we are excited to see how the design performs next season!
As far as we know this is the first spray in place concrete amphibian fence and we are looking forward to your feedback! Please don't hesitate to let us know what you think, and be sure to keep your eyes out for TOADFEST next August where you can come help the toadlets cross the road and have a real impact on this fragile ecosystem!