Dee Holladay. A trip down the Yampa and Green Rivers in Dinosaur National Monument commemorated the 50th anniversary of the wilderness advocacy group Living Rivers. Noted environmentalists accompanied the trip, offering up discussions on wilderness issues with passengers from throughout the country.; 06.06.2003, 12:10:22 PMDee Holladay. A trip down the Yampa and Green Rivers in Dinosaur National Monument commemorated the 50th anniversary of the wilderness advocacy group Living Rivers. Noted environmentalists accompanied the trip, offering up discussions on wilderness issues with passengers from throughout the country.; 06.06.2003, 12:10:49 PMDee Holladay. A trip down the Yampa and Green Rivers in Dinosaur National Monument commemorated the 50th anniversary of the wilderness advocacy group Living Rivers. Noted environmentalists accompanied the trip, offering up discussions on wilderness issues with passengers from throughout the country.; 06.06.2003, 12:10:21 PMA trip down the Yampa and Green Rivers in Dinosaur National Monument commemorated the 50th anniversary of the wilderness advocacy group Living Rivers. Noted environmentalists accompanied the trip, offering up discussions on wilderness issues with passengers from throughout the country.; 06.06.2003, 9:55:12 AM