LOS ALGODONES, Mexico — When the Colorado River reaches the U.S.-Mexico border, it pushes up against Morelos Dam. Nearly all the remaining water is shunted aside into an immense canal and flows toward the farmlands and cities of Baja California.
South of the dam, the last of the river disappears in the desert.
The sandy riverbed meanders on through fields of wheat, hay, cotton and vegetables, and curves past the town of San Luis Rio Colorado, where for years little or no water has flowed beneath its bridge.
