California’s largest river flows 400 miles from its headwaters near Mount Shasta to the San Francisco Bay. Its shape resembles a child’s scribbles in places, but the Sacramento River provides a demanding region with its most precious resource: fresh water. Take a trip with us along the state’s unsung architect, which paved a route that would be traversed by steamships, crisscrossed by highways, and floated by inner-tubers. … Some 75 percent of California’s water comes from north of Sacramento, but 80 percent of the demand for it comes from the southern two-thirds of the state. The river supports two million acres of farmland in the Central Valley, with water sourced mostly from melted Sierra Nevada snowpack. … The river’s fish populations—especially salmon—are very low owing to warming waters and drought, and swaths of valley farmland are already fallow. Were the river to disappear, hydroelectricity-producing dams would shut down and hundreds of thousands of homes would lose power.