[John Brooks] Hamby 27, … California’s boyish-looking representative on issues concerning the river, sat shoulder-to-shoulder with the other states’ powerful water managers, many of whom have decades of experience, an almost uncomfortable sight given their latest brawl over the beleaguered Colorado River. … Combined, these roles position Hamby as arguably the most powerful person involved in talks on the future of the Colorado River, a waterway that is relied upon by an estimated 35 million people and supports about $1.4 trillion worth of commerce. They also place him at the center of the river’s most consequential moment since midcentury, when Arizona and California went to the Supreme Court to fight over the amount of water they were allocated.