Hosmer Lake was good to us yesterday with most fish coming to the net on 2 flies. #1 was my Jiggy Damsel under an Indicator in the morning, and the rest of the day a Callibaetis Cate under the indicator was our top fly by far. There was almost no hatch whatsoever ! Weird to me as August is often a great month to see callibaetis in the morning on the upper lake. There were a lot of Damsel Adults around and a few leaping trout chasing them here and there, but not enough for me to switch over to the adults away from the nymphs that were working so well. 
The upper lake water temps are mid 50’s. That’s healthy. Watch Lower lakes temps and quit there once it goes over 67. Invest in a water thermometer like the Fishpond Digital one or the Cling Stick-On (your net) and be serious about fish conservation.