It is plausible to double our human population in the Willamette Valley without sacrificing the integrity of our natural systems. It will take a shift in attitude and priorities, and a fair amount of work. But it can be done.
Human behavior and preferences are inherently unpredictable and major shifts in social norms have occurred in the past. Thus, the unexpected is not completely unlikely, and the actual future in 2050 could be more extreme than any of the alternative scenarios presented.
You can see video of the entire Valley through historical, present, and “Three Future” conditions by viewing the Trajectories of Change video. (Requires Quicktime, 30 MB download)
You can also view the Willamette Story, which takes a more personal look at how people in the Valley are preparing for the next 50 years.
Valley view: David Welton