People have worked for a century to make California’s Tulare Basin into a food grower’s paradise. That pastoral landscape now looks more like the Pacific Ocean in many areas. Months of atmospheric river storms have pummeled the area and saturated the basin’s soil, which sits about halfway between San Francisco and Los Angeles, not far from Fresno. The rains have led to floods that damaged towns and deluged farms and have begun to refill what was once a sprawling lake. The floods have pitted neighboring property owners against one another and raised tensions over how to manage the flows, which...