I was wondering what fly patterns and techniques a person would use for the upcoming Sockeye season in Lake Washington. Any advice greatly appreciated.

A downrigger rod or steely stick off a downrigger with a very shinny flasher and bare red hooks behind it.

I'm not sure if anybody has every tried to fly fish for them. You might be able to get some to bite any Alaska sockeye pattern or nymph on the lower Cedar when it opens but I'm not sure if it is open durring the run and you aren't supposed to target them. As for fly fishing the lake your on your own. Since it is usually only open for a few days 99.999% of people troll for them using what I gave you above. To really answer your question, if you know what depth to target, try usuing a small size 8 or 6 Krystal Shrimp or something along that line. Since sockey are really attracted to flash this might be you best bet.

Here's an idead, try using a small, size 6 or 8, Flash fly made from different colors of Flashbou. Try red, orange, blue, silver, or pearl. I could be on to something here. Except you relly need to know the fish's depth and know that your fly is at that depth.

I know I'm kinda rambling here but these are just ideas.

My neighbor fishes for them with homemade "flies" which are just lures tied on a vise. He takes a long-shank hook, ties on a bunch of flashabou in silver and some red krystal flash. They are long strands and hang way back beyond the hook, making a 4 inch fly. He finishes by wrapping some red or orange hackle on the front. It looks weird, but I guess it works. He trolls around in the lakes with them up in Alaska. Says he has caught kings and sockeyes with them. (he uses pink bead-head nymphs for the silvers)
From what I have heard, the sockeyes in L. WA swim really deep, too deep for flylines to go, but give it a go, at worst you'll get skunked.

Thank you both for the info. It seems that they do run deep in the lake from the information that has been given to me. I used to catch them out of the river with a little streamer fly that was designed for cutthroat but then the water was only about 8 feet deep. I was really hoping to catch them on the fly again. They are extinct in the river I used to fish for them in (Union River, Hood Canal). I may tie up some red and pink sort of Coho Killers and troll them in Lake Washington if I go. I really hate combat fishing and the thought doesn't appeal to me but I have a good friend coming up from Oregon to fish and I will suffer through to make his trip worthwhile. Thanks again for the information.