At one time, as recently as the 1990s, there were well over 1 million acres of irrigated cotton in California, largely fed by cheap water contracts through the federal Central Valley Project and the State Water Project. Each of those countless acres of cotton consumed something on the order of three feet of water, or more, per acre of cotton a year – well over 3 million acre feet, which is close to 1 trillion gallons a year. Cotton in California was a very thirsty crop.
Back then, the Bureau of Reclamation sought to complete construction of Auburn Dam, then a $2 billion project with an estimated conservation pool of about 270,000 acre feet. The allocated cost of that water was $400 million. Some people still want to build that dam, but today it would cost between $4 billion and $6 billion and would provide only about 200,000 acre feet of usable water. The dam wasn’t built, in part because it would have straddled a sizeable earthquake fault and the cost-benefit ratio made little sense.
At about the same time, farmers were experimenting with subsurface drip irrigation to reduce the water demands of cotton and other crops. They discovered that the system – in conjunction with low-tech, root-level soil moisture meters – could reduce water consumption by about two-thirds, while increasing yield. The system cost about $1,000 per acre to install.
Had the $400 million from the proposed water yield of an unbuildable Auburn Dam, instead been invested in subsurface drip for cotton, it would have irrigated 400,000 acres, saving upwards of 600,000 acre feet of water, a far better return on investment than the dam.
It is supremely difficult to transfer money out of one government pocket into another, and no one in Washington or Sacramento had the imagination or the interest to pursue that line of thinking. After a while, cotton declined dramatically, partly because almonds and pistachios became more profitable, even though neither is essential for human food and nutrition, and mature pistachio trees require up to four feet of water per acre.