Two hundred years ago, herds of elk and antelope dotted the hills of the San Francisco-Monterey Bay area. Grizzly bears lumbered down to the creeks to fish for silver salmon and steelhead trout. From vast marshlands geese, ducks, and other birds rose in thick clouds "with a sound like that of a hurricane." This land of "inexpressible fertility," as one early explorer described it, supported one of the densest Indian populations in all of North America. One...