from www.wcmh4.com American Rivers' list of 10 rivers it says are the most endangered in 2004. American Rivers, a Washington-based nonprofit conservation group, says the rivers on the list are not necessarily the ones with the worst chronic problems, but those that they say are most in peril because of toxic chemicals, severe water shortages and other problems. 1. Colorado River. Colorado, Utah, Arizona, Nevada and California. 2. Big Sunflower River. Mississippi. 3. Snake River. Wyoming, Idaho, Oregon and Washington. 4. Tennessee River. Tennessee, Alabama, Mississippi and Kentucky. 5. Allegheny and Monongahela rivers. West Virginia, Pennsylvania and New York. 6. Spokane River. Idaho and Washington. 7. Housatonic River. Massachusetts and Connecticut. 8. Peace River. Florida. 9. Big Darby Creek. Ohio. 10. Mississippi River. Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi and Louisiana.