LAKE POWELL, Utah — Muddy water whizzed past as John Weisheit steered a motorboat upstream in the Colorado River. He revved the engine as the boat sped around a bend and up a riffle.
All along the river’s banks, giant mounds of dried mud and silt rose taller than houses — sediment that settled in Lake Powell over decades and has been left exposed by the reservoir’s retreating waters.
Suddenly, the water turned rough around Weisheit and his four passengers. The rapids rose up in waves. The boat descended in a churning brown trough and hit bottom, then popped up, throwing the passengers to the front.
