A journey down one of the last wild rivers in the American west: ‘The bullseye will always be on its back’

As US water wars rage, a tributary of the Colorado River faces unprecedented pressure. Visitors worry how long this aquatic relict' will last

On an early morning in mid-May, a group of near strangers shoved camping gear and clothes into waterproof bags, slathered on sunscreen, and ambled into the bright-yellow rafts that would carry them down one of the last free-flowing rivers in the American west.

Unhindered by large dams or diversions, the Yampa curves across 250 miles (400km) of alpine tundras, cottonwood forests and ancient red-rock canyons, rising from Colorado's Rocky mountains to where it joins with the Green River in Utah, much in the way it has for millions of years.