Diseased pine trees
Hello, the best guide to managing pine in the Willamette Valley is the OSU Extension Publication: Establishing and Managing Ponderosa Pine in the Willamette Valley. The only copy online I could find is at this website: https://www.kintighs.com/PonderosaPine_Book.htm
Also, this book is a good one for management recommendations of oregon conifers if you know the pest. https://catalog.extension.oregonstate.edu/em8980
It may be that our recent droughts have played a role in this mortality you are seeing, Although I can't say for sure what has killed these trees. It appears to be smaller trees along the edge that have died mostly? The guides linked above will help with identification of any particular pest, such as bark beetles.
I think the one photo you shared with the three dead trees are Douglas-fir, and we have been seeing lots of mortality of Douglas-fir in the Valley on tough sites like this one.
I hope these two guides are what you are looking for.