Wonder Wednesday!

UPDATE: Does this explain anything? upd 1  upd 2   upd 3   upd 4   Looks like they are either dredging or dumping as I see gravel load and a back and forth pattern in their movement, and that could definitely explain a change underneath the water.
THIS MORN: I was up with the early-birds this morning, checked the river levels which were at 4ft (Washington gauge), and found something that raises a question for me. Thank goodness there are super-smart viewers with the expertise to help me out.

Check this series of pics and let me know what you think caused this line. Is it an old bridge or pier? An anomaly on the river bottom? Very importantly to mention the first picture was taken at 6:19am est and the last one was taken at 7:20am.
pic 1   pic 2   pic 3   pic 4   pic 5 5 shows it disappearing in the sunlight.

Have a great day!

River view near Dundee
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