American Rivers is a conservation organization which is trying to save as many rivers as possible. They publish a periodic newsletter as well.
NORS ($15/1 yr, $28/2 yr, $39/3 yr) PO Box 6847 314 North 20th St., Suite 200 Colorado Springs, CO 80904 (719) 473-2466
The National Organization for River Sports is involved in conservation, safety, and other aspects of river running.
American Canoe Association 8580 Cinderbed Road, Suite 1900 PO Box 1190 Newington, Virginia 22122-1190 (703) 550-7523
American Whitewater Affiliation ($15/yr) PO Box 85 Phoenicia, NY 12464 (914) 688-5569 AWA publishes "American Whitewater" bimonthly and is involved in safety and conservation efforts. They also produce the AWA National Whitewater River Inventory; for information on ordering it, contact: Pope Barrow 136 13th St. SE Washington, DC 20003
Friends of the River c/o Kevin Wolf 902 12th Street, Suite 207 Sacramento, CA 95814 (916) 442-3155 River Runner Magazine ($15/1, $25/2, $30/3) (now Paddler) PO Box 697 Fallbrook, CA 92028 1-800-752-7951 This is the one that I read; it focuses on all sorts of river running, has great photography, and a lot of good articles.
Canoe Magazine (6 issues/$15, 12 issues/$28) PO Box 3146 Kirkland, WA 98083 1-800-MY-CANOE
I don't read this one, but I've heard that it tends to focus somewhat on flatwater cruising at the expense of river running.
Colorado Whitewater Association 7500 E. Arapahoe Englewood, CO 80221 (303) 770-0515 Or contact Bill Baker at (303) 972-8437 or (303) 790-3415 High Country River Rafters ($15/yr) PO Box 709 Golden, CO 80402 contact: Larry Stuhl 526-2426 These last two are probably only of interest to you if you live in Colorado or boat there a lot. Both organizations are involved in training, safety seminars, and group trips.
Georgia Canoe Association c/o GCA Membership Chairperson PO Box 7023 Atlanta, GA 30357 Yearly dues at $18; the club sponsors a number of trips on rivers such as the Hiwasee, Nantahala, Ocoee, Chatooga, French Broad, etc. They also run instructional, safety, and rescue clinics, as well as publishing a newsletter. You might contact Sam Smith, sam@eedsp.eedsp.gatech.edu for more info.