It might. The UW limnologist who was primarily responsible for calling the pollution to the public's attention and monitored the situation for decades did actually suggest increasing the nutrient load back into the lake for the sockeye.

I do know that because of Metro the lake is cleaner, clarity has improved a lot, and there were good changes in the plankton levels.

For a while in the 90s, when there was interest in the sockeye because of the law establishing a spawning channel or hatchery, that lots of studies were done. One interesting aspect is LW smolts are among the largest, by far, of any sockeye population. If memory serves, there is very poor survival of the fry when they enter the lake, and this may be lack of small food items. Once the relatively few fry survive, they grow like hell. I think the studies kind of petered out because of a lack of funding and the continuing low returns even with the augmented runs.