By Tim Anderson

Chinampa Gardens

Can ancient Aztec agriculture save the sinking Sacramento Delta islands?

A KATRINA-STYLE DISASTER IS BREWING in California. Halfway between Sacramento and San Francisco there’s a vast labyrinth of large islands in the Sacramento-San Joaquin River Delta. It’s rich cropland, a popular recreation area, and home to suburban neighborhoods.

Unfortunately the islands are sinking, as fast as 3 inches a year. Levees hold back the water, but some fields are more than 25 feet below sea level. All the islands have flooded at least once. When that happens, thousands of acres are inundated, and saltwater ...

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