I got up at 3:15 AM and was on the water at Medical Lake by 4:25 AM. The lake was like a mirror. I saw small trout (perhaps a foot long) jumping for flies all during my 4-hour fishing session, but none took my lure. I was using a 3/8-oz. silver Kastmaster slab jig with a single barbless hook, since this is a "Selective Gear" fishing lake. In my canoe, I worked the entire shoreline by casting and retrieving the lure in a sideways jigging motion. I worked multiple depths of water by counting-down the lure for 3 seconds, 5 seconds, 8 seconds and even 10 seconds to see if the fish were suspended above the thermocline. I was spray-casting on both sides (towards the shore and towards deeper water) as my canoe drifted in the breeze about 1 foot per second. The trout just were not interested in my lure, even after I ran it past their surface splashes. They wanted INSECTS today, I guess. I have had success at other Spokane-area lakes with the Kastmaster, but not here today.
There was another fisherman fishing off of the small cliff near the public boat launch area, and he was casting a Woolly Bugger. He said he had a strike but it got off. By the time I left at 8:30 AM, two other fishermen arrived. I don't know if they would have any better luck than I did.
I should have gone to nearby West Medical Lake, which I drove by on the way home. There were ~15 vehicles there and several bank fishermen by the public boat launch on the south end. Oh well.