Based on what I can see in the photo (white fluffy growth on leaves) it looks like you may have aphids. There are two main species of aphids that attack beech trees in this region, the Beech blight aphid (Grylloprociphilus imbricator) and the Woolly beech aphid (Phyllaphis fagi) (https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/beech-fagus-aphid). It is hard to see exactly how extreme the infestation is since there is poor lighting in the photos, but it looks like the spread is quite extensive. Insecticidal soap sprays and narrow range oils can be used to control them, but considering the size of the tree, I suggest hiring someone with a pressure blast sprayer to spray. If the aphids are already protected by curled leaves, then a systemic pesticide, such as acephate, can be used instead. You can also try hitting them with a strong stream of water from a garden hose to wash them off. Check the undersides of leaves to see if you have removed them all. Continue to monitor and check the leaves periodically, and hit them with a stream of water if they continue to build up. There are several natural enemies that help to control aphid populations. You can plant flowering plants around your garden to attract natural enemies and help restore the natural balance (the following publication has a list of flowers to attract natural enemies: https://catalog.extension.oregonstate.edu/pnw550). If you see ants crawling around the tree you should try to control them as well, since they "farm" aphids to harvest honeydew and protect aphids from natural enemies. If you see ants climbing up the tree, place a band of sticky material (e.g., Tanglefoot) around the trunk. For more control options for aphids in the landscape, see: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html and http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/woolaphids.html