The San Joaquin Valley is the agricultural powerhouse of the United States and California. California accounts for an eighth of U.S. farm sales, largely because it produces high value fruit and nut, vegetable and melon, and horticultural specialty (FVH) crops such as nursery products and flowers. Over three-fourths of the state's $37 billion in farm sales in 2010 were crop commodities, and almost 90 percent of the $28 billion in California crop sales represented labor-intensive FVH commodities.

About half of California's farm sales and farm employment are produced in the eight-county San Joaquin Valley with four million residents that stretches from Stockton in the north to Bakersfield in the south. The leading U.S. farm county is Fresno, which had farm sales of almost $6 billion in 2010.

California's rising water supply

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California, which had one of its wettest years ever in 2016-17, declared a drought emergency in January 2014 and ended it in April 2017. Over 30 inches of rain fell in parts of the Central Valley that normally receive less than 20 inches, and some Sierra mountain areas received over 60 feet of snow.

Instead of worrying about whether there would be enough water for summer irrigation, many water managers worried about having enough room in dams and reservoirs to prevent flooding. The water content of the Sierra snowpack, which normally peaks in April, was over 160 percent of average in April 2017, compared to five percent of average in April 2015. In 1983, the April Sierra snowpack had a water content that was over 200 percent of average.

California normally uses about 33 million acre feet of water, including 26 million acre feet for farming and nine million acre feet for consumers and industry. Among urban residents, half of water is used for lawns and landscaping.

In normal rain years, about 38 percent of the water used for agricultural irrigation is groundwater. During drought years, less surface water is conveyed via dams and canals, and groundwater is 60 percent of agricultural irrigation water. Land often subsides as water is pumped from underground, falling 50 feet or more in many areas of the San Joaquin Valley during the 2012-16 drought.

 

California's largest dams are Lake Shasta, operated by the federal government, and Lake Oroville, operated by the state government. With water rushing in, Lake Oroville's spillway was opened February 7, 2017, and a gash appeared that forced a brief evacuation of almost 200,000 residents living below the 770-foot high dam.

California has 1,400 dams and 13,000 miles of levees to keep water in rivers and to prevent the flooding of islands in the Sacramento-San Joaquin river delta. By one estimate, up to $50 billion is needed to repair federal and state dams and levies to ensure that they can withstand heavier winter rains.

The dam and levee system faces another threat: climate change. If global warming means that more precipitation falls as rain rather than snow during the winter months, dams that were built primarily to collect snow melt for summer irrigation could be forced to release rain water in winter to prevent floods.

In response to more water flowing into the ocean in 2016-17, California plans three new storage projects: Sites Reservoir to store 1.8 million acre feet, Temperance Flat to store 1.3 million acre feet, and raising the 602-foot high Shasta Dam by 18.5 feet to increase its capacity by 634,000 acre feet.

Most new water storage facilities are north of the Sacramento-San Joaquin Delta, raising the challenge of moving more water through or around the Delta while protecting fish. The state's plans to build $15.5 billion twin, 30-mile-long tunnels beneath the delta are moving very slowly.

The U.S. Bureau of Reclamation announced in March 2017 that Sacramento Valley and Friant customers can expect 100 percent of their water allocation in 2017, but Central Valley Project customers could expect at least 65 percent and perhaps 80 percent. Westlands Water District, the largest U.S. agricultural water district, called for 100 percent of CVP water deliveries.

The 350-square mile Salton Sea is California's largest lake. Created in the early 1900s when canals bringing water from the Colorado River to the Imperial Valley overflowed for two years, the Salton Sea reached its heyday in the 1950s, when it was the playground of the Hollywood elite. Since then, evaporation has increased salt levels and shrunk the Salton Sea, killing fish and allowing fine dust to circulate and threatening 400 species of migrating birds. A $9.6 billion revitalization plan has not been implemented.

This post was published in the most recent Rural Migration News from April 2017.

Rural Migration News summarizes the most important migration-related issues affecting agriculture and rural America. Topics are grouped by category: Rural America, Farm Workers, Immigration, Other and Resources.

 

There are two editions of Rural Migration News. The paper edition has about 10,000 words and the email version about 20,000 words.

 

Distribution is by email. If you wish to subscribe, send your email address to ruralmigrationnews-subscribe [at} primal.ucdavis.edu. Current and back issues may be accessed at http://migration.ucdavis.edu.

 

The paper edition is available by mail for $30 domestic and $50 foreign for one year and $55 and $95 for a two-year subscription. Make checks payable to Migration Dialogue and send to: Philip Martin, Department of Ag and Resource Economics, University of California, Davis, California 95616 USA.

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Philip Martin is Professor of Agricultural and Resource Economics at the University of California- Davis, chair of the University of California's Comparative Immigration and Integration Program, and editor of the monthly Migration News and the quarterly Rural Migration News.

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