Give Victor Babbitt of Tahoe Fly Fishing Outfitters
a call. He will give you the most to up to date info.
If I was going up this coming weekend, I would have confidence in tan caddis (Bird's Nest, Bird of Prey, Fox's Pupa) in sizes 12 to 14 for the nymph or tan caddis (Elk Hair Caddis, EC Caddis, X Caddis) in sizes 14 to 16 for the dries.
Also bring a mix of PMD mayflies, Yellow Sallie stoneflies, and midges. It may be early, but a good heatwave could bring the hoppers to the water.