As many times as I've been over there to visit family, I've never fished Duck. It looks like a really good lake though. Some of those canals look like they should be packed with slabs during early Spring. There's tons of crappie dying of old age right here in Seattle since nobody really fishes for 'em :D.

If you live close to Union Kokanee King I'd spend as much time as I could out there. There are some monster crappie in there if you put in some time. I've got pics of a pair of 15" slabs I pulled out of there that will go up on the site soon. The hard part is finding them. You might catch 40 fish off a rock break one night then only 8 the next night on the same spot. Find yourself a few good humps, a point, and a couple rock flat break-points and you should be able to get a few each time you head out. The key to the crappie in lake Union is the night bite and rock structure.