Interstate 70 Exit 204 Eastern end of the Colorado River SR 128 Scenic Byway. Elevation 4,370 feet. West access via Interstate Highway #70 to communities of Thompson Sprs. Utah - Crescent Junction, Utah - Green River, Utah. Green River State Park Campground. Camping; RV Trailer Sites – 42 Maximum RV Length - 45 ft. Tent Sites – 40. -- Start / Finish of Road Map Travel Guide. -e Upper Colorado River Scenic Byway Follow the mighty Colorado River through its beautifully carved redrock gorge and travel back 250 million years in time. If it all looks familiar, it may be that you recognize the scenery from several western movies and commercials.