I don't see the money going through a suction dredge and ending up that condition (paper or rubber bands).. 3 packets together.. hard to believe.. if they were separate they wouldn't land together, if they were rubber banded together I can't see a rubber bands not breaking and packets separating.. the only possibility is they went through in some container.
Lots of ways the money could get there.
There was a 200,000 cu yard erosion mitigation project in 1976/77 on Sauvie right across and just upstream of TBAR.. clamshell dredge and barge material from down the Columbia.. even mouth of Lewis..
I think a later jump over the Willamette Valley can't be ruled out, money brought to TBAR via Willamette River.
also, working on this one,, money discarded by somebody other than the hijacker, (but not planted) in the mid/late 70's...
There is also a very remote theoretical possibility that the TBAR money wasn't part of Cooper's ransom.. but that is too upsetting for some to even consider, especially those that don't understand the fragile and unverified process that created the FBI bill list.
There was a rogue garbage dump surrounded by the Slough a few miles upstream of TBAR..
etc. etc.