 The Cascadia Bioregion is also referred to as the Pacific Northwest Bioregion and encompasses all of the state of Washington, and portions of Oregon, Idaho, California, Nevada, Wyoming, Montana, Alaska, Yukon, and British Columbia.Bioregions are geographically based areas defined by land or soil composition, watershed, climate, flora, and fauna.The Cascadia Bioregion claims the entire watershed of the Columbia River (as far as the Continental Divide), as well as the Cascade Range from Northern California well into Canada.