I used Ron Watters' "Guide to Idaho Paddling" when I canoed from Eagle down to Middleton. Excellent book! Library here in Boise should have it. If you are going to float from the WW park to Glenwood, I would just keep going! The river past the Glenwood bridge just keeps getting more primal. It was a great float when I did it a couple years ago. There were a few spots to portage around downed trees, but if the flow is low enough there's plenty of time. Hope that helps.