The Thirst Quenchers — Rick Raphael

With the age of nuclear power, the need for hydroelectric sources vanished and with it went the great dams and reservoirs with their vast, wasteful surfaces of open water that evaporated by the thousands of acre-feet before ever being utilized by man. The beds of the great rivers were dry and the cities spread upon them together with the new controlled auto-farms. Only the smaller rivers and streams continued to flow until they reached a predesignated flow force. Then they vanished, spilling down into tunnels and flowing for hundreds of miles along subterranean aqueducts into great storage reservoirs beneath the surface of the land and protected from the drain of the sun and wind. From these, each precious drop of water was rationed upwards to meet the increasing needs of the people. And still there was never enough.