Hello,

It looks like you have several pests. The white fuzz is caused by a eriophyid mite. These tiny arachnids cause odd plant growths, which the white fuzz is. Unfortunately, treatment is tough as the mites are microscopic and you will have an infestation before you see the white fuzz which tells you you have mites. Also, they usually burrow into the leaf, which inhibits your ability to get a pesticide on them. If this is something you are seeing year after year you can treat the tree preventatively earlier in the summer with a horticultural oil or broad spectrum insecticide which is approved for use on mites. You will also have to ensure the product would be safe to use near water bodies. Use of any pesticide in a riparian area requires a special permit from the Alaska Department of Environmental Conservation.

Your other pest is one of the many Alder sawflies. These are small caterpillar looking larvae which is likely the cause of the holes in the leaves. They have since moved on as that damage is old. Check the trees earlier in the year for any signs, like small holes, or the actual sawfly larvae. They can be dislodged from the tree with strong jets of water. Cleaning around the tree in the fall to remove any leaf litter they may be using as a home for the winter will also remove some of the pest load. 

Neither of these pests usually cause too much harm to trees. It's important to make sure the trees are healthy, which means enough water and proper fertilization.