This site analyses shows the ecoregion of the Willamette Valley, it shows how the area has changed throughout the years. I have included site diagrams  which show the Willamette Valley at a large scale and have also shown the Woodburn area at a smaller scale. These maps show the existing rivers, wetlands, and large parks that inhabit the area.  Also check this article I found, about the Hispanic Community in Woodburn, Oregon.