Virtual water from a vanishing river

The Colorado River Basin fCRB) supplies much of the water underpinning the mushrooming growth of several cities in the American Southwest, notably Los Angeles, Calif.; Las Vegas, Nev.; and Phoenix, Ariz. Although water managers diligently track its distribution and use to the seven basin states, their accounting is incomplete; they do not track the transfer of "virtual" water that is embodied in products exported from the basin, notably electricity. This article quantifies the amount of water used to generate electricity within the entire Colorado River watershed and then estimates how much of this water is transferred as an indirect, hidden, and unpaid allotment to destinations outside the CRB. The authors calculate that thermoelectric stations within the CRB evaporate about 330,000 acre-ft of water annually to produce electricity, roughly the amount that would supply the domestic needs of more than half a million households located in a place like Phoenix. Of that volume, nearly half is exported-virtually-to distant customers, particularly those in the Wasatch Front of Utah and those in Southern California. As water demands attract increased scrutiny, such transfers will acquire greater saliency to policies about land use, water price, and future allocations.