Published on The Water Blog

Innovative solutions to water scarcity: what we can learn from California’s heartland

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Water Banking - Water Association of Kern County Water Banking - Water Association of Kern County

When most people think of California, they think of extremes. The glamor of Beverly Hills and the storied grit of the state’s inner cities. The endless coastline and the vast desert. The Hollywood Hills and Humboldt County’s Murder Mountain.

But California’s most important contribution may come by way of agriculture. The state’s Central Valley region alone produces more than 200 cash crops, including more than half of the vegetables, fruits, and nuts grown in the entire United States. Its four million residents generate a GDP of nearly $160 billion making the Central Valley’s economy roughly the size of New Zealand’s. Put plainly, the Central Valley is one of the world’s most important guarantors of food security.

Agriculture can thrive in hot weather and cold, in ample sunlight or heavy cloud cover. It cannot succeed, however, without water.  The Central Valley has nearly every climactic advantage necessary for sustained high-volume food production, but its semiarid climate and erratic surface water levels have always posed a challenge to farmers, and those challenges have only grown more severe in recent decades. When water runs scarce, current crops are threatened, farmers’ ability to plan is severely curtailed, and both public health and a vital regional economy are placed at grave risk.

Because predictable availability of water is so crucial to the region’s economy, some communities have taken bold steps to manage water use. Kern County, which occupies the Central Valley’s southern end, has been particularly innovative. Its groundwater banking programs began as a crisis response but matured into a sustainable mechanism by percolating excess surface water in the wetter years in 7,000 acres of recharge ponds across the county to assist in maintaining a stable groundwater supply.

The operation of Kern Water Bank (KWB) allows users to forgo a portion of their shares of the municipal water supply during times of adequate rainfall, store it underground, and have water available for use during dry seasons . Kern County’s groundwater banking system is one of the oldest and most effective in the entire country – and some say the world. Importantly, its success relies on a carefully balanced network of stakeholders:

  • Local municipalities have broad discretion over how their water allocations are meted out.
  • Urban-rural integration coordinates the supply of water for various uses, which allows the system to anticipate which parts of the county will demand the most water throughout the year.
  • Independent funding allows the water banking program to grow without fear of drastic changes at the county, state, or federal level.
How much water can the Kern Water Bank recharge into the groundwater aquifer?

A brief history of the KWB

The KWB traces its history back more than one hundred years ago, when the Kern River was first diverted to irrigate local agricultural land. The earliest version of this irrigation system had to rely on snow melt from the nearby Sierra Nevada mountain range, making it entirely seasonal.

The 1920s saw the advent of the deep well turbine pump, which granted farmers access to groundwater in the absence of surface water, such as that provided by the Kern River. Cotton, a lucrative but thirsty crop, became immediately popular in the southern Central Valley, with expanded acreages leading to critical depletion of groundwater.

Water banking had been discussed at the state level as an answer to the chronic water shortages facing Kern County and other California regions, but no major projects came of the deliberation until 1991. Following a prolonged drought, the state created its first emergency water bank. The success of that program, and the opportunities it revealed for improvements to its banking mechanism, encouraged entities in Kern County to develop their own self-contained water banking program, the KWB, in 1996.

Where state-wide water banking initiatives tended to suffer from the sheer scale of their ambitions, the KWB faced a related challenge of balancing urban and rural demand for water.

Bakersfield, which sits in a desert environment at the south end of the Central Valley, accounts for well over half of Kern County’s population. Its value as a commercial, political, and social hub is offset by the steady and growing demand its citizens placed on Kern County’s groundwater supply. More than 70% of Bakersfield’s drinking water, for example, is pumped from groundwater reserves on a typical day; before the KWB’s launch, groundwater reserves in the immediate Bakersfield area were critically depleted. The remaining supply is derived from the Kern River and the California Aqueduct, each of which is highly subject to variability due to droughts.

The KWB was put to the test during a five-year drought that ended in 2016. During the worst of the drought, the California Aqueduct supplied no water to municipalities, and the Kern River produced only one eighth of its typical volume. Water drawn from the KWB’s groundwater reserves helped both Bakersfield and Kern County’s agricultural regions continue to operate under conditions remarkably close to normal, allowing the county to maintain greater continuity than many other areas of central California.

The KWB’s success proves that careful planning and good-faith cooperation between urban and rural areas can stabilize water supplies, provide mutual resilience to drought, and increase both water security and economic prosperity. 

To learn more, read Water Scarce Cities: Thriving in a Finite World, which shares the experiences of cities worldwide that are building resilient water supply systems in increasingly water scarce environments.




Lauren Nicole Core

Special Projects, Water Global Practice, The World Bank

Stephane Dahan

Senior Water and Sanitation Specialist, Water Global Practice, The World Bank

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