Nooksack River at Hannegan Road Bridge, Lynden, Washington
The Nooksack typically is not ths muddy this time of year, so I suspect the mud was the result of a very large landslide and mud flow into the river in the headwaters of the Middle Fork on Mount Baker AERIAL VIEW.
Dave Tucker has been covering and acting as a conduit for the recent big landslide and debris flow off of Mount Baker into the Middle Fork Nooksack River. For those not linked into Dave's great work:
In addtion Steph Abegg has some aerial images http://www.stephabegg.com/home/photography/aerial/36.