Ground Water in North America

Abstract

lar or thin in others, and in some large areas not found at all. Some of the reservoirs are offered more replenish­ ment from rain or from streams than they can accept; others receive negligi­ ble inflow. Moreover, an unmeasured but sizable proportion of the available ground water does not meet prevailing high standards of purity. And finally, these natural peculiarities are not the only source of man's difficulties with the ground-water supply. By his use of land and water man may alter the be­ havior of ground water in unpredict­ able—or, more properly, unpredicted —ways, with sometimes dismaying and irreversible effects.