There are no prairie dogs in WA State. Any reports to the contrary will turn out to be some sort of ground squirrel.
Of the 6 species of ground squirrel in WA, 3 are protected: The Golden-mantled ground squirrel (
Spermophilus lateralis), the Cascade golden-mantled ground squirrel (
Spermophilus saturatus), and the Washington ground squirrel (
Spermophilus washingtoni). The Golden-mantled ground squirrels look a lot like chipmunks, so you would not easily mistake those. The Washington ground squirrel is a little harder to distinguish from some of the non-protected species.
The 3 non-protected ground squirrels are the California Ground Squirrel (
Spermophilus beecheyi), the Columbian Ground Squirrel (
Spermophilus columbianus), and Townsend`s Ground Squirrel (
Spermophilus townsendii).
If you Google those species you should be able to find photos to help you distinguish them. The known range of the Washington ground squirrel does not overlap much with the non-protected species, so that should also help. You can view maps of their known ranges by looking them up on this page:
http://wdfw.wa.gov/conservation/gap/mammals.htmlA list of protected species in Washington State is here:
http://apps.leg.wa.gov/wac/default.aspx?cite=232-12-011