The answer to decreasing supplies of freshwater is not to try to supply more.8 Human beings already use one-fourth of the earth’s total water in natural circulation, and over half of the accessible runoff.9 New dams might modestly increase available runoff but are costly and environmentally damaging. Even if most of the good sites had not already been taken long ago, no supply strategy could keep pace with the present rate of population growth and demand.10 While population will probably increase 45 percent in the next thirty years,
increases in accessible runoff are projected to be only 10 percent. Even after investing some $400 billion in water supply over the past century,11 the United States, with all its wealth and technical prowess, faces shortages that have no easy remedies. As one authority put it in 1984, “The water supply of the West is nearly fully utilized. It is difficult to see major construction projects which will add significantly to the current supply.”12 Moreover, America’s eighty thousand dams and reservoirs were not entirely benign: During the boom years of watercapturing projects, the United States lost over 60 percent of its inland wetlands, polluted half its stream-miles, and lost or badly degraded many major fish runs.13 At home and abroad, with water as with energy, the only practical, large-scale solution is to use what we have far more efficiently.