Sierra Garter Snake Posted on August 18, 2018 by Mike Pingleton Leave a comment Thamnophis couchii (Kennicott, 1859) Yuba Co., California. May 7, 2014. Found on the banks of the Yuba River, up in the Sierras. A handsome snake, in an understated way. This species is featured in my Notes From The Field blog post ‘Thamnopalooza‘. My Flickr album for this species is here.