Groundwater is back in the spotlight. Largely invisible, lightly regulated and used by 85% of California's population and much of the state's $45 billion agriculture industry, groundwater is a crucial reserve that helps stave off catastrophe during drought periods like we've experienced over the past three years.
But after more than a century of unregulated use, California's groundwater is in crisis – and with it the state's hydrologic safety net. This carries profound economic, environmental, and infrastructure implications. How did it come to this, and what do we do now?
Over 6 million Californians rely solely or primarily on groundwater for their water supply. Many of them reside in towns and cities in the Central Valley and along the Central California coast, where communities generally have limited local surface water options or don’t have the ability to finance other water supply sources.
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Other cities and towns heavily dependent on groundwater include Lodi, Woodland, Willows, Orland, Portola, Alturas, City of Fort Jones, City of Mt. Shasta, Tulelake, Dorris, Weed, Maxwell, Fall River Mills, Porterville and many others.
Generally, though, groundwater is used alongside surface water to meet the state’s needs, which range from urban and industrial uses to irrigating roughly half the fruits and vegetables grown in the United States.
In normal and wet years, groundwater provides 30 to 40% of the water supply. It supplements surface water that is collected from snowmelt and rainfall then is stored and conveyed by a vast system of state and federal dams, reservoirs, and aqueducts.
During droughts, surface water availability can be sharply reduced, leaving water users to pump water from local wells. At times like these, groundwater can surge closer to 60% of water used statewide, and even higher in agricultural areas like the Central Valley.
This year, the third consecutive year of an extreme and extensive drought, state officials have warned that little or no surface water will be made available to most consumers. In turn, water providers are advising large users to pump their own groundwater.
As bad as this drought is, it is not uncommon. Droughts are a part of life in California, as anyone who has lived here long enough knows. But what most may not know is that groundwater has been getting us through droughts, including the last big one in the 1970s, and it is getting us through the one today.
In fact, 5 million acre feet of additional groundwater will be pumped in the Central Valley alone to make up for the 6.5 million acre feet in surface water reductions for agriculture in 2014. Even so, the economic loss for the Central Valley from this drought is expected to be $1.7 billion.
Imagine the economic impact if groundwater is not there to cushion us for the next big drought.
Writers often turn to financial metaphors to explain the importance of groundwater. As Tom Philpott of Mother Jones magazine wrote recently, “To live off surface water is to live off your paycheck ... To rely on groundwater, though, is to live off of savings.”
Another metaphor frequently applied to groundwater is that of mining. In fact, “groundwater mining” is exactly what experts call nonrenewable groundwater use, where farmers “mine” water to grow almonds, alfalfa or grapes. You could even say they are “mining” those commodities themselves.
How did we get to this point? Partly because using groundwater is as simple as drilling a well and pumping it out. Many in California regard land ownership as a license to use groundwater; in the absence of any monitoring or accounting, it tends to happen with no strings attached.
There are ways to limit groundwater use to the “safe yield” of the basin, but this only happens if someone sues and the basin is “adjudicated,” or if the local government or water management district steps in with a strong groundwater management plan and supporting local ordinances.
In the past, natural recharge was enough to establish a balance between water pumped out and precipitation filtering back into the ground. But starting with the arrival of powerful electric pumps in the 1920s, Californians began to take out more water than nature could put back.
Today, estimates say that places like the Central Valley are withdrawing groundwater at twice the rate of natural recharge. To exacerbate the situation, many of the open spaces that could help refill aquifers are now covered over with houses, roads, and parking lots.
Pumping groundwater in excess of the rate of natural replenishment lowers the water table. Spread over a number of years without recovery, this is called “overdraft” – or “O.D.”
Back in 1980, 40 of California’s 450 groundwater basins were judged to be in overdraft, with 11 more identified as in “critical” status. Although the state has not updated the surveys in the last three decades, the Department of Water Resources recently reported that across most of the state groundwater levels have dropped 50 feet below historical lows, with levels in many areas in the San Joaquin Valley more than 100 feet below previous historic lows.
Just knowing how much groundwater is being pumped is a challenge: In most cases, users are not required to report how much water they have taken. Exceptions are basins governed by legal adjudication, local government regulations or a few groundwater districts that operate under special state legislation.
In the absence of disclosure by users, researchers and regulators have found other ways to estimate how much water is being taken out of the ground.
The conventional method is to measure the acreage of different crops and deduce how much water would be needed to grow them. But more recently, scientists from Stanford, the U.S. Geological Survey and NASA have turned to satellite data to measure the rate of groundwater withdrawal.
Read more about the issues surrounding groundwater monitoring and reporting in our article “California’s Missing Metrics.”
These new remote sensing and modeling techniques have added detail to the picture of overdraft in California, perhaps nowhere more dramatically than in the Central Valley, the nation’s salad bowl. A 2013 report by the US Geological Survey (USGS) estimated that from 1900 to 2008, Central Valley aquifers lost 140 cubic kilometers of freshwater – an amount roughly four and a half times the capacity of Lake Mead in Nevada, the nation’s largest reservoir.
A recent follow-up study found that groundwater loss in the Central Valley is gaining speed: Another 20 cubic kilometers over the two years beginning in November 2011.
Over and above the loss of water resources, groundwater overdraft can harm surface water rights; diminish river flows; impact fish, animal, and plant communities that depend on groundwater; increase energy costs from pumping; and result in economic impacts on agriculture that depends on groundwater.
Many parts of California are well acquainted with groundwater overdraft. One of the most visible signs of overdraft is the gradual sinking of the ground — called subsidence — as groundwater depletion continues over time in a basin. The Central Valley has been sinking over the course of the 20th century, a condition that has been described as the single largest human alteration of the earth to date. Estimates of the cost of infrastructure repairs necessitated by overdraft between 1955 and 1972 run to what would be $1.3 billion in 2013 dollars.
Overdraft’s toll was instrumental in leading the federal government and the state of California to build two mammoth aqueduct projects: the Central Valley Project and the State Water Project. These brought surface water from the mountains, through the Sacramento-San Joaquin Delta, and on to the Central Valley and points far south – over 700 miles of canals and pipelines.
For a while, these surface water deliveries helped alleviate groundwater pumping in San Joaquin Valley. In recent times, though, population growth and increases in agricultural water use have soaked up the extra capacity they provided.
There are exceptions to the larger story of decline. Some places, such as the Santa Clara Valley, experienced plummeting groundwater levels and land subsidence of 12 feet before the introduction of imported surface water in the 1960s. This imported water, along with other supply diversification measures, allowed groundwater levels to recharge and stabilize over time. The land subsidence, however, was mostly permanent.
A number of other places in California have also been managing groundwater successfully for decades through special water districts, and sometimes through adjudication. Learn more in Uncommon Innovation: Developments in Groundwater Management Planning in California.
What are water users and utilities doing to cope with the two-pronged challenge of drought and depleted aquifers? Unfortunately, there are few incentives – and few regulations – to encourage groundwater conservation. Groundwater moves freely underground without regard for property lines, so there is little incentive for an individual pumper to curb his usage while his neighbors continue to freely draw from the same aquifer. This highlights the need for basinwide agreements or solutions in alleviating groundwater problems.
A recent case in Merced County where two landowners proposed a $46 million sale of approximately 100,000 acre-feet of groundwater over four years to neighboring Stanislaus County. Neighbors are concerned about how this pumping would impact their wells, since they share the same aquifer.
While ultimately the original proposal was scaled back to 46,000 acre-feet over two years, the case highlights the need for basinwide agreements, regulations or other solutions to address groundwater conflicts arising throughout the state where some stand to gain, but many others — including the environment — stand to lose.
In addition to drilling more wells, and deeper wells, farmers are increasingly planting higher-value orchard and tree crops and like apples, almonds, pistachios and wine grapes, all of which have to be maintained year to year and cannot be fallowed – meaning they must be irrigated every year or die. This eliminates year-to-year flexibility in water use.
Urban growth is another recurring water demand that is hard to reduce. Although California law requires developers to secure adequate water supplies for very large housing complexes, most projects fall well below the existing law’s 500-unit threshold.
Jay Famiglietti, a water expert at the University of California at Irvine, sums up the situation in a blog post: “Perennial orchard crops, flood irrigation and our front lawns are literally sucking us dry.”
“The current conditions almost demand regulation,” writes the syndicated newspaper columnist Thomas Elias, who points out that most of California’s significant environmental laws were passed in the face of dire crises.
The administration of Gov. Jerry Brown has presented a water action plan that calls for better local and regional groundwater management, with a warning that the state will step in if it sees the need to do so. This plan, alongside a deepening drought and worsening groundwater conditions across the state, has generated considerable interest in improving groundwater management.
Through numerous hearings, workshops, and consultations with experts and interest groups, recommendations by groups such as the California Water Foundation are coalescing around the concept of local groundwater management with the state serving as a backstop authority if local action has not occurred or is insufficient. Next steps might include creating and empowering local groundwater management entities; requiring groundwater management plans; and defining the state’s role for assistance, oversight, enforcement and funding. Read more in the California Water Foundation's report with recommendations for sustainable groundwater management.
In signs of a major shift, the Association of California Water Agencies – a trade group representing California water utilities that had previously opposed regulation – recently issued a set of recommendations that included monitoring, controlling pumping, and even charging fees for groundwater use as potential options for improving groundwater management. Other recommendations included increasing groundwater storage and removing impediments to recharge; restricting new perennial crops and urban development in unmanaged and impacted groundwater areas; and collecting data and making it available to the state and to the public.
The current severe drought is exposing the vulnerabilities caused by our limited oversight of groundwater as California’s population grows and land uses change to meet agricultural and housing demands. The demands on groundwater will be further exacerbated by climate change.
Some other factors seem to be arising in favor of more oversight of groundwater use. For instance, conflicts over groundwater resources are increasingly pitting neighbors against one another, softening opposition for more groundwater use oversight. In addition, groundwater management requires a regional approach as aquifers tend to be larger than the boundaries of cities, counties, and individual water agencies.
A fundamental need for improved groundwater management is a better understanding of our groundwater aquifers. Using new tools like geophysical technologies, we have the capacity to understand aquifers in a more cost-effective and less intrusive way than ever before.
Other articles in this series will explore the lack of data collection and sharing in California, how existing legal structures lead to groundwater conflicts, and the promise of groundwater recharge to work alongside improved groundwater management.