Changing Patterns of Ground‐Water Use in the United Statesa

Abstract

ABSTRACTThe increasing use of ground water and its true role as a source of water supplies in the United States have sometimes been interpreted incorrectly. The total use of ground water has indeed increased tremendously during the last 20 years (by almost 80%), but so has the total use of water (over 70%). And ground water is still far from being a primary source of water supplies. In 1975, only 20% of the total amount of water withdrawn in the United States for various uses came from ground‐water sources.Statistical analysis of ground‐water data for the period 1950‐1975 has shown that the ground‐water usage is changing only very slowly. Relation of ground‐water use to total water use expressed in percent was used as an indicator of changes of ground‐water use patterns. This percentage has not changed significantly, and it has fluctuated around 19%. In 1975, only 6 States used more ground water than surface water for their water supplies, and in 23 States ground‐water use was less than 10% of total use. Even more unfavorable is the magnitude of change in ratio of ground‐water use relative to total water use. From 1955 to 1975 only 13 States show an increase in the ratio. In 28 States the ratio has decreased, and in 7 it has remained the same.