Completed during Harry Truman’s presidency, the Friant-Kern Canal has been a workhorse in California’s elaborate man-made water-delivery network. It’s a low-tech concrete marvel that operates purely on gravity, capable of efficiently piping billions of gallons of water to cities and farms on a 152-mile journey along the east side of the fertile San Joaquin Valley. Until now. The Friant-Kern has been crippled by a phenomenon known as subsidence. The canal is sinking as the Valley floor beneath it slowly caves in, brought down by years of groundwater extraction by the region’s farmers.