Thank you for your question. It is fairly common for all conifers (including pines) to exhibit late summer and fall foliage loss (i.e. yellow to reddish-brown foliage). One would usually observe this on older foliage and branches, whereas newer foliage (usually at the branch tips) remains green. Most conifers only retain their foliage for a certain amount of years, and they cast off older foliage (anywhere from 2 to 11 years old depending on the species) at the end of the growing season. This is a completely natural process and does not damage the tree.
That said, it does appear that you have a significant amount of foliage loss. I notice the browning primarily on older branches but certainly on some newer growth, too. Long spells of hot, dry weather in late summer can exacerbate the visibility of foliage loss, which may be the case with your tree considering the past few hot, dry summers in the Willamette Valley.
I suggest keeping an eye on your pine over the next year. It is likely to improve in appearance as it sheds yellow needles and restores its moisture levels over the winter. If you continue to see browning throughout the winter and next growing season, the trees may be declining. In that case, consider contacting an International Society of Arboriculture certified arborist to assess the tree.