By the time the Sacramento River winds its more-than-400-mile course from the slopes of Mount Shasta past the state capital, it’s well into its leisurely stride, running slowly by fields of sweet corn, tomatoes and alfalfa.

But this lazy stretch of river, just south of Sacramento, is a metaphorical whitewater. The rural Sacramento County town of Hood, at the north end of the Sacramento-San Joaquin River Delta, is where state and federal authorities have planned the starting point of California’s hotly debated tunnel project.