A new federal study has found that groundwater levels in the San Joaquin Valley of California have dropped to near-historic lows as pumping and drought have prevented the replenishing of the aquifer.
The U.S. Geological Survey study found that the valley has lost 60 million acre-feet of groundwater since 1961 — enough to supply every California household for 10 years. The study also reports that groundwater pumping continues to cause the valley floor to sink.
The California Aqueduct, which delivers drinking water to more than 20 million people, is among many structures threatened by the sinking. Claudia Faunt, the study project chief, said about 20 percent of the groundwater pumped in the U.S. comes from under the Central Valley, the country’s largest farming region.
Mike Wade, executive director for the California Farm Water Coalition, offers the following comments on the groundwater study and the water crisis in California:
“A recent study by the U.S. Geological Survey on groundwater in California's Central Valley surprised some folks by identifying declining groundwater levels in the Tulare Basin portion of the San Joaquin Valley. Those involved in the water industry were not so surprised and a look at history explains why.
“Farmers responded in the early 1900s to the encouragement to settle the land along the west side of the San Joaquin Valley and quickly turned the land into productive fields. Key to this conversion was the use of groundwater to irrigate the fields. The demand for farm products spurred farmers to greater production and an increased use of groundwater.
“It soon became evident that groundwater pumping was causing subsidence problems in isolated areas. Subsidence occurred in areas where the underground that once hosted the water collapsed after the water had been removed. Some of these areas are still evident today, namely in the community of Three Rocks along Highway 33 on the west side of Fresno County.
“One of the driving forces to construct the federal Central Valley Project was the opportunity to turn farmers away from groundwater by providing a reliable surface water supply. Contracts were signed and pledges were made to deliver water to these farms.
“The subsidence issue faded as surface water was delivered that was not only consumed by the crops in the fields but also helped to recharge the groundwater levels.
“When periods of drought occur as we are now experiencing, farmers turn to their groundwater pumps to provide the water needed to continue their operations that provide the food and fiber that is shipped around the world and also provide employment opportunities. Multiple-year droughts that disrupt the delivery of surface water increase the rate of water pulled from the underground. We are now in a third consecutive year of drought and few along the valley's Westside are surprised that groundwater levels are dropping.
“Westside farmers have survived droughts before but this time around court-ordered restrictions of water delivered southward from the Sacramento-San Joaquin Delta to protect endangered species have added to the need to pump groundwater. Some individuals and organizations point an accusing finger at farmers for this increased pumping. Yet, it is these same groups who have vociferously argued for less water to flow from the Delta to farms and cities. One could argue that it is these groups who are forcing farmers to increase their groundwater pumping that is causing groundwater levels to drop.
“Perhaps relief will come in the year ahead as weather forecasters are already calling for a wet winter that will recharge the water supplies in our state. Yet, a wet winter does not necessarily mean that restrictions will be lifted in the Delta to allow water to return to previous delivery levels.
“If relief does not come to Westside farmers, through both a return to normal weather conditions and relaxed restrictions on delivery, then groundwater levels may continue to drop.”
Source: California Farm Water Coalition and Western United Dairymen