navy base help?
I just noticed you have a naval base at the mouth. Has your group ever approached them? They might be willing to lend some equipment in the interest of community relations. Also, posting up on the base’s bulletin boards (online and/or physical) might get some more volunteers for the trash clean-up. Since the guys and gals based there are likely to be in good shape, this might be especially helpful if you have to muscle a car carcass onto a jon-boat-platform.
The maps weren’t as helpful as I had hoped. Your area is just slightly beyond the boundary of the Terraserver Urban Areas series – literally a few hundred feet away - so no new images there. The images on Google Earth are pretty good. You can make out car-sized object on the road and individual trees in the woods, but I couldn’t spot the trash piles anywhere near the area indicated.
Is that dark area to the right of your target area in the Google Earth image standing water? I presume that’s the reclaimed gravel pit you mentioned. Is its level substantially higher than the river and where the trash is?
If it is, then here’s one more suggestion, probably useless since it depends on a lot of ifs, but you never know. If the gravel pit water level is higher, and if it’s near the trash and if you have access to some large diameter hose, and if some of the large pieces are buried and need to be dug out of the mud (that’s 4 big ifs), then you could set up a siphon and use the running water to help expose the big pieces of trash.
Okay, that’s pretty crazy, I’ll admit, but siphons are cool (in a science-nerdy sort of way). I actually had occasion to make use of the principle once on a friend’s farm, and he was so impressed that I’ve been looking for another application for years now.