Water is a finite but crucial resource. In most river basins around the world, water is diverted for industrial, municipal, and domestic consumption. It’s also a critical component of wetlands and other natural ecosystems that are of tremendous value to society.
Worldwide, the bulk of water use is tied to agriculture—it accounts for approximately 66 percent of water diverted from natural sources for human use and 85 percent of water consumption. In the arid western United States, it’s not uncommon for irrigation to represent 75 percent–90 percent of all diversions.
Historically, much of the development that’s made these diversions possible in the United States was subsidized by the federal government. This, together with water rights mechanisms that tend to preserve agriculture’s favored access to the water supply, has made water relatively inexpensive for agriculture.
Few farmers have had much incentive to achieve greater efficiencies in their use of water for irrigation. As a result, the amount of water diverted for irrigation is about two to three times as much as is needed for crop production.
On average, more than half of the water diverted for irrigation percolates into the groundwater or returns to surface streams without watering crops.
