The idea is old, but the route is new. In the past year, I have worked with an energized team at Greater Hells Canyon Council to remap a thru hike spanning the Blue Mountains of northeast Oregon, which we also refer to as the Greater Hells Canyon Region.
In June, my wife and I went to the upper valley of Eagle Creek together, from the place called Boulder Park. There is no longer the resort that is shown on old USGS topographic maps. That improvement (its removal) must have happened shortly before we settled in Oregon and set up camp for the long term, about 26 miles downstream, about 26 years ago, for the map says "field checked 1987."
Spring is the right time to be in Hells Canyon. Between the mud and silence of winter and the inferno of summer (it’s called Hells Canyon for a reason, remember) is a brief window of soft warm rain and rapid greening.