Actually compared to the rest of the Sound the Canal is pretty clean. The real nasty stuff, like PCB, DDT, PAH, etc. is pretty low as there has been little if any industrial development. Contrast this to Tacoma and Seattle where there are superfund sites all over the place. The problem with the Canal is circulation, or actually lack thereof. The standard load of crap from failing septic systems and municipal sewer outfalls has no where to go in the Canal, so the nutrients just hang around and grow plankton, which use up large amounts of dissolved oxygen when they die, thus killing everything else that needs O2 to live. Dilution is not the solution to pollution here, the solution is to keep it all out. And the only way to do that is get the houses and septic systems off the beach, get people and their septic tanks out of the floodplain, get sewage treated to class A standards and infiltrated back into the aquifer, outlaw fertilizers on lawns, capture and treat stormwater runoff from roads and parking lots, fence the cows, horses, and pets out of the creeks, and get the tribes to quit dumping millions of pounds of dead fish into the water after they strip out the eggs. Piece of cake. Anything short of this and you can kiss the Canal goodby - or actually if you did that hepatitis or worse would kill you