I’ve been up and fished Lost Lake twice with no luck. There are some nice cutthroats that cruise around in there. I presented to them very carefully and they would just look at my fly and turn away. One of them even violently shook his head at it. I digress. That’s a nice area. I would recommend Boulder Lake and drainage from Rock Creek TH. If you’ve got the legs for it, you would definitely find solitude (even Mt. Solitude) at Upper Boulder Lake. If you’ve really got your legs under you, I hear the Slate Creek drainage (once again from the Rock Creek TH) is excellent, but I’ve yet to make it up there.