Well, why all the mystery? count the upper labials and let us know. All T. elegans subspecies have 8. Also, is the base color of the snake solid as it appears in the photo? or does it have spots like this wandering?

T. elegans vagrans (wandering garter)





"mountain garter" T. elegans elegans (keep in mind both of these snakes are considered "western terrestrial" garters, just two different subspecies)
Note the 8 upper labials (like all T. elegans subspecies have) and lack of distinct spots: