California’s Looming Water Disaster

By Dr. Robert Thorson

Earth’s most precious fluid is not gasoline, but the tiny fraction of Earth’s water that is neither frozen nor vaporized, low enough in salinity to be considered fresh and free enough of contaminants to be legally potable. By mid-century, its price will be on people’s minds the way liquid fuel is today.

My biggest concern is California, which has an enormous population, carries national economic clout and has the nation’s most vulnerable large water supply system.

In adjacent Arizona, the main problem is too little supply for too much demand. In California, it’s the environmental degradation of the West Coast’s largest estuary, the severe effect of long-term water rationing on our national economy, and a human catastrophe with a 95 percent certainty of happening before 2050.

When the engineered levees failed in New Orleans during Hurricane Katrina, the disruption to the water supply was local and temporary because the city wasn’t a public water supply for tens of millions of people living elsewhere. Not so for the Sacramento-San Joaquin Delta, which drains into San Francisco Bay. It provides water for approximately half the population and for irrigating the state’s richest agricultural region. As with the Mississippi, the Sacramento-San Joaquin Delta is also a soft, muddy place in the process of subsiding below sea level, and is protected by more than a thousand miles of engineered levees. The main danger in California is “The Big One,” a high-magnitude earthquake emanating from the San Andreas-Hayward Fault system, now overdue.

“California is now in its third year of drought, and long-standing tensions over water are boiling to the surface.” That’s the lead sentence from a NewsFocus article in the March 27 issue of the journal Science, shortly after a bold action by Gov. Arnold Schwarzenegger.

In February, he declared a statewide water emergency, giving state government the power to impose severe rationing. According to one economic model, a 15 percent reduction in water supply would cause a loss of 95,000 jobs, many of which support agricultural field workers and their families. Luckily, unexpectedly heavy snows in the high Sierra after the declaration brought temporary relief, though the long-term prospect remains dire.

The hub of California’s water delivery system occupies the southern part of the coalesced Delta. There, runoff from snowmelt and rainfall in the northern Sierra, which flows down the Sacramento River, is pumped into either the Central Valley Project for agricultural use or into the State Water Project for domestic and municipal consumption. These two projects compete like a pair of prizefighters throwing lawsuits instead of punches. But in this analogy, the main problem is that the boxing ring is ready to collapse underfoot.

One day, two events will synchronize to bring California’s water system down. The first will be a higher-than-normal spring flood in the distributary channels of the Delta. This will be a consequence of unusually rapid spring snowmelt caused by the warmer temperatures predicted by climate change models. The second event will be an earthquake strong enough to loosen or liquefy the levee soils. Salt water from San Francisco Bay will rush in to fill the basins caused by soil subsidence, raising the salinity near pumping stations to the point where the water will remain unusable for either crops or municipal supplies for many years. Jobs will be lost, food prices will spike, rationing will be severe and the scramble for more reliable sources will intensify.

A partial solution to this problem is to build a peripheral canal around the Delta toward the thirsty southern half of the state. This would reduce the risk of a water catastrophe and help restore the Delta toward its more natural ecological flow regime.

Friday is the deadline for public comments on the California Water Plan Update 2009, Strategic Plan. You may comment on this national issue at, or via your friends or family who live there.