California is sinking. In the Central Valley, the most productive agricultural region in the US, some areas drop an inch or two per year. Telephone poles slump, roads crack, canals fail. In time, all that sinking adds up. A recent state survey found one patch of farmland off I-5 near the town of Arbuckle had fallen 2 feet in nine years.
The culprit: overdrafted aquifers. The process speeds up during periods of drought, when rivers run dry and farmers scramble to find other ways to water their fields. “It’s a tragedy of the commons situation,” says Alex Johnson, fund director for the Freshwater Trust, a conservation nonprofit. “Everyone is incentivized to pull as much [water] as they can as fast as they can.” Usually, that means less water for future droughts; the rare wet years in between fail to replenish California’s subterranean emergency fund.