Level IV: (3d) Valley Foothills
The Valley Foothills ecoregion is a transitional zone between the agricultural Willamette Valley and the more heavily forested Cascade and Coast ranges. It contains rolling foothills with medium gradient, sinuous streams, and a few buttes and low mountains, rising to an elevation of approximately 1,500 feet (457 m).
The region receives less rainfall than its more mountainous neighbors, and consequently the potential natural vegetation is distinct. The eastern foothills are wetter than those that lie on the western side of the valley in the lee of the Coast Range. Historically, the drier areas supported Garry oak and madrone woodlands and prairies, with California oatgrass, fescue, blue wildrye, brodiaea, and other prairie forbs; while the moister areas supported Douglas-fir forests, with sword fern, oceanspray, hazel, baldhip rose, poison oak, and alien Himalayan blackberry.
Today, the valley foothills are characterized by rural residential development, pastures, timberland, vineyards, Christmas tree farms, and orchards. The largest of the Willamette Valley subregions, it covers 2,415 square miles (6,255 km2) in Oregon and 112 square miles (290 km2) in Washington.