Both Lava Lake and Little Lava Lake are fishing quite well and most days you should expect a good callibaetis dry fly session, and all days with nymphs of this important mayfly to our regional lakes. There are many great callibaetis nymphs but the callibaetis cate which a adaptation of the old Cate’s Turkey fly I discover in the 80’s tying flies out of Randall Kauffmann’s nymph books is one of my absolute go-to flies from size 14 to 18. I am working on some further ideas on making it even more fishy, so stay tuned to that. A poxyback cb, and a simple fly we get from Umpqua called a callibaetis nymph (very original I know) are good stripped on a variety of sink tips and full sink lines, or as a dropper on the tag with a CB cate or jig red PT as the point. I also really like the Howard Croston cb nymphs that match his drop back bung indicators, and at these lakes this fly is really productive. 
Chironomids in red, olive, black and window tint from #14 to 18 are essential to fish the Lava’s. 
Beetles have been particularly good, and the RP ant and flag ant should be used now too. 
Damsels are getting active here, and balanced leeches are super important at times.