You mention desert, but I am unfammiliar with any desert setting in the pacific north west... Most of it (as far as I have experienced) is watershed forest, mountains, and glacier. In fact, the closest area that I can think of off the top of my head that could be considered 'desert' is the interior BC around kamloops/Vernon (about 6 hours from Seattle). Even then it's not a desert like the Sahara or Mohave... (interior BC = avg rainfall of 10cm annually, mostly scrub land. Pine forrests... But 3 major rivers.... North Thompson, South Thompson, Fraser).
In SR, it is all tribal lands consisting of towns, forests, mountains meadowland and watersheds. Great landscape to get lost in an death from exposure is a constant threat for the unwary. Natural predators include wolves, cougars, bears (black and grzzily), wolverines and an assorted list of awakened nasties as well. Food sources are the hardest part as well as temperatures, dangerous environmental hazards (cliffs, steep hills, mountains, etc)
If looking for a desert, there is the baja and mojave deserts of California...