I've located a photo taken from the exact same angle, photographed on July 5, 1980. Photo illustrates mud and log debris and the elevation of mudflows on the steelwork of the bridge.
http://libraryphoto.cr.usgs.gov/cgi-bin/show_picture.cgi?ID=ID. Mount St. Helens Schuster, R.L. 36ct
(You'll need to copy and paste the entire URL into a new browser window)
Mud from the May 18, 1980 eruption came close to overflowing the deck of this span. Photos at the USGS website illustrate mud coming up to the bottom of the steel truss on it.
Hello to you. Do you know what happen on May 18, 1980? That is lucky bridge over Toutle River. Because of lahar and hot water from Mount St. Helens Volcano Eruption. Lahar or hot water of lava were damage two camelback truss on highway state route 504 and railroad bridge near freeway I-5 and other bridges near Mount St. Helens. They check bridge is safety. THANK YOU