I have encountered Western Diamondbacks on the American River, on the Bear River at the campground, and above Folsom Res. on a ranch. They are there because all the rattlers got loose from the old snake farm at Colfax around WW II !I certainly know what a Dback looks like being from AZ and Texas! These "experts" on snakes and spiders are comical! They try to claim there are no brown recluse spiders in N. Cal. Heck, I had a major infestation of them in a trailor I had in Nevada City. I have a scar bigger than a quarter on my leg from a recluse bite that occured in Mammoth Lakes, CA, in the Sierras. I had bought a trailor from a hippie girl that came from San Gabriel, CA....the same place that the first brown recluse occured in Cal, back in '71. The spider bit me that was hiding under the bed! I have also been nailed by two black widows TWICE! Man, that is painful! And attacked by a Bull Shark in Corpus Christi Bay, and barely got away from it. I have had a lot of Bear encounters to, including Grizz!