Nowhere is the salinity problem more serious than in the San Joaquin Valley of California, the most productive farming region in the entire world. There you have a shallow and impermeable clay layer, the residual bottom of an ancient sea, underlying a million or so acres of fabulously profitable land. During the irrigation season, temperatures in the valley fluctuate between 90 and 110 degrees Fahrenheit; the good water evaporates as if the sky were a sponge, the junk water goes down, and the problem gets worse and worse.
