In speaking to what causes fish kills, they state:
“Fish kills occur due to a cascade of natural events. Dense marine water enters Hood Canal and lifts water with low oxygen levels toward the water surface. As river inflows decline during the dry season, the freshwater cap on the surface thins. Southwest wind events push this thin cap to the north, which allows low-oxygen water beneath it to surface rapidly.”

It seems to me that as the easily movable thin freshwater cap on the surface (that gets pushed north) is primarily to blame for allowing the low-oxygen waters to rise to the surface, then wouldn’t the highly decreased freshwater flow in the south Hood Canal (especially from the now dammed Skokomish River) be a huge factor? Wouldn’t a thicker freshwater cap be less susceptible to southwest winds and not allow low-oxygen waters to rise so rapidly?

Again though, it’s a complex system and I agree with you that the fact that “we don’t have all the answers is not a failure but an indication of the complexity of the system being studied.”

One of the great assets we have today is a series of monitoring buoys that help predict coming fish kills and help us know what is going on day to day. See the blog I wrote last October about becoming a low-oxygen nerd.