Hosmer Lake is good right now, with a strong afternoon callibaetis hatch, plus some traveling sedge which gives you an opportunity to skitter a big goddard caddis and get some hard takes! We are getting to the time where a little mystery bug occurs and they are called Alderflies. A black #14 elk hair caddis is a good match, but know these are not actual caddisflies. 
Damsels are getting very active here, and while we haven’t seen the fish getting too excited for the adults, the nymphs are very important now. Leeches, chironomids, scuds, soft hackles and blobs are good choices around the upper and lower lake and in some cases are the best bets in the channel. I’ll sometimes fish a booby on a type 3/5/3 in the channel and kind of walk the dog with the buoyancy of the booby but I know its getting down on that triple density line. 
years ago I remember really dedicated Hosmer anglers would fish type 3 lines with dragonfly nymphs and cast it across the channel, let it sink down to the mud and wait for the cruisers to swim by and they’d start the retrieve…
A couple of differences today compared to then is the filament algae that grows on the bottom in so many places would makes a mess of the fly before it was shown swimming around the fish, and with the low waters at Hoz this season it is worse than normal in a lot of spots. 
Also, did you know Hosmer Lake was originally named Mud Lake? I am glad the name changed.