Good news for this early in the season. The fish are concentrated in several areas of the lake, & feeding on midge larva in less than 15 feet. Stage up on a clean mud bottom in 12-15 feet, and you will get that Under-Cator dunking! Sandy Pt., McGee Bay, & Hilton Bay have been the best locations. The Crowley slam, (rainbow, brown, &  cutthroat) is likely for proficient still water nymphers as all species are on the chew. The Sacramento Perch are currently spawning on the sandy bottoms. If you plan on still water nymphing- I suggest using copper/dark tigers, dark- long shank crystal zebras, BB (broken back) tiger midges, BB gillies, standard gillies, crystal emergers/midge pupa, crystal leeches, & dark assassins. My choice for first casts would be a standard #18 gillie as the upper, with a #18/16 copper tiger/zebra midge as the dropper. BB patterns will fish better if the surface is textured due to wind. You can periodically “twitch” your Under-Cator to give some animation to the flies if it is glassy; or calm.