There's a ton of suckers in Washington and Sammamish that spawn in moving water. They could be suckers, peamouth chub, or lake whitefish which all spawn in moving water.
Here's a largescale sucker:
http://www.fishingwithrod.com/fish_p...ale_sucker.jpg
A peamouth chub (they get a lot bigger in Washignton):
http://worldanglr.com/photo_essays/a...l_IMG_3023.jpg
Lake Whitefish:
http://www.huntingandfishingjournal...._whitefish.jpg
The only other thing I can think of are trout which still spawn in the slough or maybe cutthroat?
