That is so sad that they found that much stuff, but I do want to thank them. Are family is heading there again next year and thanks to them we know we will find natures beauty not man's garbage. 
Lee and Pamela - thanks for the kudos. This group has hosted this event, I believe, for 12 years now. They are also active in a number of other projects that incorporate the local youth and help give them a hands on look at conservation in action.
Todd - I agree. I have taken part in these events and it never ceases to amaze me what is found along the banks of our rivers. Some of it is due to spring flooding, some is due to legacy attempts at bank stabiliaztion projects and some of it is simple disregard for our natural resources. The Yellowstone does not see the throngs of recreational floaters that the lower Madison does. The lower stretch of the Madison turns into a beer can recepticle when the "bikini hatch" comes out. Have a great trip out next year.
All best,
Jason
Jason, this is a great hyper-local post. Congratulations on the Yellowstone River clean up project and your chapters involvement in helping to keep the rivers cleaned up!