so looking at that chart.... and knowing salmon habitat.... and never having been there in my life...

I would start above the fish ladder as close to the ladder as possible. I know at lower granite by Pullman we fished within feet of the top of the ladder. no Idea whats legal here but I would want a steady amount of fish coming by my gear. bobber eggs or bobber shrimp try to find out at what depth the fish ladder top is and stay within 5 feet of that depth for about 50 yards in all directions. from there I would go up stream to those pilings nearest to the fish ladder. stay as close to the structure as I could. my last try would be upstream to the 7 on the map... it looks like a nice point with a deep drop to 25 60 then 102.... fish the down current side of that at all depths till I find them... if none of that worked I would go up to hat rock park looks like some water dumps in there so you might find some checking that smell out. last of all I would go up in a large boat with good eletronics and hit the lee side of the old gravel bars and high spots on the bottom. much harder to find and stay on but there should be fish there.

good luck.