Title Page of a well-used Stevens Guide....

The Stevens Guide is printed on water-resistant paper with water-resistant ink, and will survive being completely soaked. However, if you aren't careful drying it, the pages will stick together, and the book will become a rigid solid mass. So you should buy two copies -- one to keep out during the day, and one safely in a drybag for perusal in camp.

Larry Stevens is a Research Biologist who has also been a commercial oarsman, and he packs an astonishing amount of information in slightly over 100 pages of maps and text:

"The Colorado River in the Grand Canyon", by Larry Stevens. Red Lake Books, PO Box 1315, Flagstaff, Arizona 86002. I forget what it cost -- not much. But remember -- you want two copies.