Seams like cougar has been brought up a few times recently. try to dig through the archives for some info. I can't help you much unless you are going to be in a boat and even then my advice and experiance is minimal but we did well last summer using flashers and worms a good 100' back trolling all over the lake. did good above slide. below slide on the same bank. along the road to the hot springs against the bank in various spots. up in the arm to the other ramp and down by the dam. couldn't narrow down the best productive spot.
I've only fished Cougar a few times. I managed to catch fish two of those times. Here's a google link at where I caught my fish. I caught a bunch of landlocked chinook using a thomas lure at the tip of this point. Google Maps and I caught a 17 inch cuttbow on a half of night crawler with no weight somewhere along this bank not too far from the camp ground on the forest service road on the east side of the lake. Google Maps