Groundwater to the rescue in drought-stricken California – but not without costs
This week, UC Davis released a final report on the economic impacts of this year’s drought on California’s agricultural industry. Groundwater pumping, the report says, will significantly soften the drought’s blow to farm operations, easing anticipated losses statewide to $2.2 billion from the $3.6 billion the industry projected earlier this year.
Groundwater represents the vast majority of California’s known freshwater resources, with storage capacity ten times the volume of the state’s surface reservoirs, pooled in natural underground aquifers.
Source: CA Department of Water Resources
But our overreliance on groundwater during dry years has significant negative consequences, and may not even be an option in the near future. Rapidly increasing groundwater extraction coupled with a long-standing absence of monitoring and management standards in California has resulted in substantial water table decline, setting the stage for a “tragedy of the commons.”
A Critical Buffer
Many California communities have turned to groundwater during dry years when the state and federal water projects turn off the faucet. In a typical year, Californians rely on groundwater for about 40 percent of our total fresh water supplies, but that figure soars to over 60 percent in times of drought.
Many rural areas of the state, as well as some sizable cities such as Fresno, rely almost entirely on groundwater basins. When managed sustainably, this water supply can offer a reliable lifeline for water districts and farmers, compensating for 75% of the reductions to irrigation districts from the aqueducts this year alone.
Liquid Gold Rush
Source: Dick Ireland, USGS
This response to minimal rainfall is in no way sustainable. California’s drought, now in its third year, has resulted in a veritable frenzy of water drilling in the Central Valley. Water well drilling companies such as Rottman Drilling Co. have year-long waiting lists as farmers scramble to keep their crops alive. The rising demand for water also translates into higher prices, making it even more profitable to drill new wells and sell water to parched water districts.
This liquid gold rush comes at a price. Aquifers can lose their integrity as irrigation and drinking water sources if water tables drop too much. Many underground reservoirs also gradually buckle under the weight of the land above them when too much groundwater is depleted. A recent report from the US Geological Survey found that in the San Joaquin Valley, where families, farmers, and oil companies compete for limited water resources, a span of 1,200 square miles is slowly sinking – to the tune of nearly 30 feet over the last 50 years.
Recent research from the University of Nevada at Reno has also linked the observed uplift of the Sierra Mountain range and increases in seismic activity along the San Andreas Fault to groundwater depletion. The researchers claim that land subsidence due to excess water pumping even caused parts of the Central Valley Water Project, which conveys surface water from northern to southern California, to collapse, incurring millions of dollars in damage.
Population growth and climate change are the twin elephants in the room, adding even greater pressure to this limited resource. Simultaneous decreases in precipitation and increases in groundwater pumping – also known as overdrafting—work together to create a highly unsustainable situation. In particular, overdrafting can result in water contamination from encroaching coastal seawater, rendering wells unusable. Drilling is also highly energy intensive, and the more groundwater we extract, the more energy-intensive it becomes to access that water, as well levels sink, requiring more energy to bring the water to surface. The UC Davis researchers estimate the drought has added nearly half a billion dollars in energy costs for farmers for groundwater pumping alone.
Balancing the Groundwater Checkbook
At the moment, California is the only western state aside from Texas that does not have a statewide system of groundwater management in place.
"We’re running down our bank account,” said Richard Howitt, professor of agricultural and resource economics at UC Davis and a co-author of the drought impact study. “We’re like somebody who is so rich that we don’t have to balance the checkbook ... we still think we’re in a groundwater-rich era.”
If California is going to balance the groundwater checkbook, and it’s imperative we do so soon, the state is going need better data. What little information is gathered about wells sits under lock and key at the Department of Water Resources, inaccessible to most outside of state research and regulatory groups due to an archaic California Water Code section protecting water well drilling companies’ data from competitors.
The Golden State can draw from several strong precedents for effective groundwater management at the local level. In Southern California, where two-thirds of the state’s population lives in an area that receives only one-third of the annual precipitation, Orange County has a wildly successful groundwater replenishment system. The county recycles wastewater, which is then pumped back into the groundwater basin to maintain the water table and prevent seawater intrusion. In Monterey County, where overdrafting brought up groundwater with crop-killing salinity levels, they similarly began recharging their aquifer to fight salt water intrusion and keep the water table at a sustainable level.
Unfortunately, sustainable management plans such as those in Orange County are the exceptions to the rule. Many of the most vulnerable areas of the state remain at serious risk of permanently depleting groundwater resources or rendering existing sources useless due to contamination. State policymakers should support Senator Pavley’s groundwater management bill to develop a framework to encourage conservation, recycling, and aquifer recharge strategies that provide more teeth and support to regional oversight bodies under the Department of Water Resources. We need a better understanding of the availability and sustainability of groundwater resources, and also of how much energy is being used to pump them.
Groundwater saved our agriculture sector this year. But unless we act now to stabilize and conserve perhaps our most valuable commodity, it won’t be there in the future when we need it most.