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The Central Valley Was Built to Irrigate 750,000 Acres. It May Now Have to Fallow the Same Number.
California's Central Valley uses less than 1% of US farmland to produce 8% of the nation's agricultural output by value, a quarter of everything Americans eat, 40% of the country's fruit and nuts, and a third of its vegetables. None of that was inevitable -- it runs on a water system that started as a failed California state bond measure in 1933, was rescued by a federal Depression-era takeover in 1935, and was expanded decades later by a second, separate state project built to irrigate 750,000 acres of farmland. That same acreage number is now the one California's own regulators project could go out of production, because the system that built the Valley was never actually designed to be sustainable long-term -- the same over-allocation mechanism this site already traced on the Colorado River, run on a different river, decades earlier.

Start with a number that sounds like a rounding error until you check it against the country's dinner plate. California's Central Valley uses less than 1% of all US farmland.[1] From that sliver of land, it supplies 8% of America's total agricultural output by value, roughly a quarter of everything the country eats, 40% of the nation's fruit and nuts, and a third of its vegetables.[2] None of that is native productivity. Left to natural rainfall, most of the Valley floor is semi-arid grassland. Every part of that output runs on water moved there on purpose, by a system built twice, eighty years apart.

<1%of US farmland the Central Valley occupies
8%of the nation's total agricultural output by value it produces from that sliver
1 in 4food items on an American table that trace back to it

The first system started as a state project the state itself couldn't pay for. California conceived the Central Valley Project in 1933 as a state-funded plan to control flooding, generate power, and move water to the drought-prone San Joaquin Valley -- but the state couldn't sell the voter-approved bonds during the Great Depression.[3] In 1935 the federal government took the project over, looking for exactly the kind of large public works that could put people to work.[3] Construction of its first piece, the Contra Costa Canal, began in October 1937. The finished network, built by the US Bureau of Reclamation, still moves water more than 400 miles, from Lake Shasta in the north down to Bakersfield at the Valley's southern end.[3] The system that made the Central Valley possible exists because a state project failed on its own and the federal government absorbed it -- not because a market found the water and decided to move it there.

The second system was built later, on purpose, to do something the first one wasn't designed for. California's State Water Project, built through the 1960s and 1970s, is a separate system from the federal Central Valley Project -- constructed specifically to supply more than 27 million Californians and 750,000 acres of farmland at once.[4] That single design choice is the whole tension the rest of this piece runs on: one system, built from the start to serve both the state's cities and its farms out of the same finite supply, with no mechanism built in for what happens when there isn't enough for both.

The same mechanism this site already found on the Colorado River Seven states wrote a 1922 water-sharing formula for the Colorado River during the wettest decade the basin had seen in centuries, and gave away more water than the river actually carries -- a legal allocation disconnected from the physical supply, discovered the hard way decades later. That piece is here; a companion piece on what a 1980s zoning choice did to a Phoenix-area drought cutback is here. California's own system ran the identical mechanism on a different river, a decade earlier -- a system sized for growth, not for the years the growth would eventually run into.

What happens when there isn't enough for both is no longer hypothetical. Much of the southern Central Valley -- California's largest farming region -- has been pumping groundwater faster than it recharges for years, overdrafting by close to 2 million acre-feet annually, more than 10% of the region's net water use.[5] California signed the Sustainable Groundwater Management Act into law in September 2014, requiring local water agencies to finally bring their basins back into balance and end that long-term overdraft.[6] The Public Policy Institute of California's own analysis of what balancing those basins will actually require: as much as 750,000 acres of San Joaquin Valley farmland -- out of 4.5 million irrigated acres total, roughly one in five -- may have to come out of production entirely.[7]

750,000 acres is not a coincidence worth skipping past. It is the exact acreage the State Water Project was built, on purpose, to irrigate. Sixty years after a system was sized to add three-quarters of a million acres of farmland to what the Central Valley Project already watered, California's own regulators are now measuring the balance-sheet correction in the identical unit -- the same number, run in reverse, on the same ground.

The takeaway California's Central Valley uses less than 1% of US farmland to produce 8% of the nation's agricultural output by value -- a quarter of everything Americans eat, 40% of the country's fruit and nuts, a third of its vegetables. None of it is native productivity; all of it runs on water moved there by two systems built sixty years apart. The Central Valley Project started as a 1933 California state bond measure that failed to sell during the Depression, forcing a 1935 federal takeover -- the same over-allocation mechanism this site already traced on the Colorado River, run on a different river a decade earlier. The State Water Project, built in the 1960s-70s, was designed from the start to serve both 27 million residents and 750,000 acres of farmland from one finite supply, with no mechanism for what happens when there isn't enough for both. That question stopped being hypothetical with chronic groundwater overdraft and the 2014 Sustainable Groundwater Management Act -- California's own regulators now project up to 750,000 acres of San Joaquin Valley farmland may have to come out of production. The same number the system was built to irrigate is now the number it may have to give back.
Sources
  1. USGS California Water Science Center, California's Central Valley
  2. House Committee on Natural Resources, California's Central Valley: Producing America's Fruits and Vegetables
  3. US Bureau of Reclamation, The Central Valley Project - Introduction
  4. California Department of Water Resources, State Water Project History
  5. Public Policy Institute of California, Groundwater in California
  6. Wikipedia, Sustainable Groundwater Management Act
  7. Water Deeply, California Groundwater Law Means Big Changes Above Ground, Too