The earliest Spanish explorers of California reported to their superiors that the Sacramento valley was a patchwork of desert and swampland, unsuited either to human habitation or to agriculture. How astonished they would be to see the valley today, with its thriving cities and prosperous farms. That transformation-from desert and swamp to the agricultural abundance celebrated here in Edible Sacramento-depends entirely on the manipulation of water in time and space. Water is stashed away in the wet season and redistributed to where it is needed in the dry season.

Water management in California started with the gold rush. The gold miners learned how to move water around in order to keep it flowing through the sluices of their mining rigs. As the gold petered out and the miners turned to agriculture, their skills in diverting water were readily transferred from mining to farming. By the 1860s, impressive irrigation works had been constructed by former gold miners in the alluvial fans of the rivers flowing from the Sierra Nevada.

Those early irrigation works developed into our present-day system of dams, weirs, reservoirs, sumps, flumes, canals, and pipelines that store and move water through California-a triumph of civil engineering. But equally impressive is the legal structure that allows water to be taken from one place and used in another without resulting in open warfare. The system of water rights has grown over centuries like a coral reef, with accretions of dispute and adjudication laid down over earlier layers of custom. Embedded deep within this structure are ecological crimes and social injustices that cannot easily be jack-hammered out. Attorneys crawl over the surface, patching defects or making them worse, as their clients prefer. A sane person, sitting down to design a rational program of water use for California, would not come up with anything like what we have now. This demonstrates once again that evolution is more inventive and surprising than intelligent design.

For all that, the system works pretty well-in a wet year. It is a sequence of dry years that reveals the system's weaknesses. And it is probable that in the next decade or two, we will experience a prolonged drought that will strain the system to its breaking point, both the engineering side and the legal side. It will be an interesting time. (That prediction of drought is based partly on historical patterns of rainfall and partly on the acceleration of climate change. When we think of surface water storage in California, we think of lakes and reservoirs and a few flooded islands in the delta, but our major storage is snow. And even a tiny change in climate can radically alter the timing and volume of snowmelt.)

The principal human use of water in California is farming. And the crops are far from equal in their demands for water: some (alfalfa, corn, rice) are excessively thirsty; others, like dry-farmed wheat, use no irrigation at all. Ideally, the mix of crops grown in the state would be determined by the complex relationships of their ecological and financial costs and benefits, as sorted out in a free market. But we do not have free markets in agriculture. During the Great Depression, the federal government, with good intentions and poor results, began to manipulate markets by means of quotas and subsidies, a practice that has grown into a monster of entitlements. And so we have corn and cotton in California, which are ecological failures but financial successes due to their subsidies

Favoring unfettered markets for farm products does not mean that one is a libertarian, however. Most thoughtful farmers welcome government regulation of agriculture; that is, regulation of environmental protection, public health and safety, quality standards, accurate labeling, resource conservation, and fair employment practices. We know how crazy our neighbors are, and regulation protects us from their follies. It also gives the rest of the world confidence in California's agricultural products. What is inappropriate is government regulation of markets which, left alone, regulate themselves far more efficiently than any scheme hatched by a bureaucrat. Get rid of the corn and ethanol subsidies, which were created merely to purchase votes in Iowa, and we would quickly stop wasting California's precious water on corn.

If free markets are efficient for distributing crops, why not set up a free market for California water? This idea has zealous proponents, but it is inappropriate for a vital necessity such as water. Free markets are good at setting prices for discretionary items; they are less good at allocating resources; and they are dismal at allocating scarce, critical resources in a society with large inequalities of wealth. There is an old saying that water flows uphill toward money. In a purely free market for water, golf courses would flourish in the desert while crops withered in the valley, and if the result were a tripling of the price of food, the rich would hardly notice, while the poor would go hungry. So how might water be fairly and reasonably distributed in California? It is presumptuous to attempt an answer in a few sentences, when half a dozen closely-reasoned books are published on the subject every year. But let me share my vision, anyway. First, the welfare of rivers and estuaries must be attended to. Secondly, water use-household, farm, and industrial-must be measured. The water then should be priced (or taxed) on an upward-sliding scale. Each household and irrigated farm would be entitled to a modest amount of water at a modest price. If you choose to use more than that amount, then the price per unit would rise rapidly. For example, a household might be allotted five hundred cubic feet of water per month, at ten cents per cubic foot. The second five hundred cubic feet in a month would be priced at twenty cents per cubic foot, the third at fifty cents, and any beyond that at one dollar. This is how residential electricity is priced in California-the more you use, the greater the cost of each additional unit, which is fair and effective, rewarding the thrifty and punishing the wasteful. Such a pricing schedule for water should be regulated so as to generate revenues for the state-not for individuals-embodying the idea that water, like air, is the common wealth of the citizens. Of course, it would be close to impossible, politically, to achieve such a system, but it is nonetheless useful to have something to aim for.

At some point, we will have a water crisis in California, and it will affect all of us, not just the farmers. The management of the crisis will have a technical side as well as a social and economic side. It might be a great opportunity to sweep away the accumulated historical water rights and to start over with a more rational system-replace evolution with intelligent design and see if we can do any better. In any event, it behooves us to be thinking about this ahead of time so that we have some notion of how to proceed, rather than waiting until the crisis is upon us.