Brown’s Canyon National Monument finally designated! President Obama designated the Brown’s Canyon National Monument today through the Antiquities Act. This legislation has been in the works for 27 years. This protection encompasses 22,000 acres surrounding one of Colorado’s most popular river segments for whitewater rafting, kayaking and fishing. This scenic section of the Arkansas River has been a very popular rafting trip for us for over 40 years. Recently, float fishing has also become popular with fly fishing enthusiasts.