Mike,

Logging, and, particularly, logging roads are a major culprit in this regard. The hydrology has been changed for a long term, permanently if present management continues.

The river went out because you got a lot of rain (check how many inches for stations around Mt. Baker, etc.) since Thursday. It was the first heavy rain of the autumn season, saturating the water table, and mobilizing a lot of dry and loose particulates that cause turbidity. The same amount of rain a month from now probably won't result in quite so much color.

The fish are used to this stuff. It won't hurt 'em. The fine sediments are much harder on incubating eggs. It collects around the eggs, deprives them of oxygen, and smothers them.

Sincerely,

Salmo g.