Besides fish it? Are you staying at the lake or in the cabin on the river?
I never did much fishing in the lake, but don't know why it wouldn't produce.
I would think you'd have most of your fun and action on the river. Lot's of great runs and holes to try flies or lures. I've never fished it mid-summer but could be some hold-over steelhead and early salmon runs going on. Spring and fall fishing was always good for trout, I would expect you'll find them there along with dollies.
Egg patterns and dry flies should get you some action if your fly fishing.
Have fun, it's a beautiful river.
we have the cabin on the lake july 19th thur the 26th