Groundwater Overpumping Causes Land Subsidence in San Joaquin Valley City of Corcoran

In the fertile lands of the San Joaquin Valley, a silent crisis brews beneath the surface. Despite urgent pleas from local officials and environmentalists, agricultural magnates continue their relentless extraction of groundwater.

The city of Corcoran, a community of approximately 20,000 residents and home to a maximum-security prison, is sinking.

The persistent over-pumping of groundwater by major landowners in the Tulare Lake Basin has initiated a slow-motion collapse of the valley floor.

The Unyielding Groundwater Extraction

(Photo : Mario Tama/Getty Images)

The San Joaquin Valley is one of the most productive agricultural regions in the world, producing more than half of the nation's fruits, nuts, and vegetables.

However, this bounty comes at a steep price: the depletion of the basin's aquifers, which are not only essential for agriculture but also integral to the community's survival.

According to a recent study by the U.S. Geological Survey, the valley has lost about 41 cubic kilometers of groundwater since 1980, enough to fill Lake Tahoe. This has caused the land to subside, or sink, by as much as 8.5 meters in some areas.

The subsidence has damaged roads, bridges, canals, and other infrastructure, posing a threat to public safety and the environment.

One of the most affected areas is Corcoran, where the land has sunk by more than 3.5 meters since the 1920s.

The town is surrounded by a levee that protects it from the floodwaters of the nearby Kings River. However, as the land sinks, the levee becomes less effective, exposing the town to the risk of inundation.

The groundwater pumping in the Tulare Lake Basin is mainly driven by the demand for irrigation water for crops such as almonds, pistachios, grapes, and cotton.

These crops are highly profitable, but also require large amounts of water, especially during the dry summer months.

The basin's surface water supply, which comes from the Sierra Nevada snowmelt, is often insufficient to meet the irrigation needs, especially in drought years. Therefore, farmers resort to pumping groundwater from wells, some of which are hundreds of meters deep.

The problem is that the groundwater pumping exceeds the natural recharge rate of the aquifer, which is the amount of water that seeps back into the ground from precipitation, runoff, and irrigation return flows.

This creates an imbalance between the inputs and outputs of the groundwater system, resulting in a net loss of water storage. The U.S. Geological Survey estimates that the average annual groundwater overdraft in the Tulare Lake Basin is about 1.8 cubic kilometers.

A Community's Plea for Survival

Emergency workers and desperate local officials had once rallied together in an effort to raise the town's levee with a multimillion-dollar effort funded by local property tax hikes and contributions from the prison system.

However, as nature proves its indomitable force, these efforts are no longer sufficient. An additional $17 million has been poured into another round of levee enhancements in an attempt to save the town.

But the levee is not the only problem. The sinking land also affects the quality and quantity of the groundwater, which is the main source of drinking water for the town.

As the aquifer is depleted, it becomes more vulnerable to contamination from pesticides, fertilizers, and saltwater intrusion.

Moreover, the reduced groundwater levels make it harder and more expensive for farmers to pump water for their crops, threatening their livelihoods and the local economy.

The situation is so dire that some residents have decided to leave the town, while others are hoping for a miracle. The mayor of Corcoran, Josephine Ramirez, said that they needed help from the state and the federal government.

She said that they needed them to regulate the groundwater pumping and to provide them with alternative water sources. She said that they couldn't keep sinking like this. She said that they were fighting for their lives.

The state and the federal government have taken some steps to address the groundwater crisis in the San Joaquin Valley.

In 2014, California passed the Sustainable Groundwater Management Act, which requires local agencies to develop and implement plans to achieve sustainable groundwater management by 2040. The act also gives the state the authority to intervene if the local agencies fail to comply.

In 2016, the U.S. Department of Agriculture announced a $10 million investment to support water conservation and groundwater recharge projects in the valley.

However, these measures may not be enough to reverse the decades of groundwater depletion and land subsidence.

Some experts suggest that more drastic actions are needed, such as reducing the amount of water-intensive crops, increasing the use of recycled water and stormwater capture, and implementing more efficient irrigation technologies.

These actions would require significant changes in the agricultural practices and policies of the valley, as well as the cooperation and coordination of various stakeholders.

The fate of Corcoran and other sinking towns in the San Joaquin Valley depends on how the groundwater crisis is resolved. If the current trends continue, the valley may face a future of water scarcity, environmental degradation, and social unrest. If the groundwater pumping is reduced and the aquifer is replenished, the valley may be able to restore its natural balance and sustain its agricultural productivity. The choice is ours to make.