Public Water Supply in the United States: Trends in Surface Storage Capacity

The public water supply of the United States is threatened by a number of factors including decreasing supply because of drought and increasing demand through population growth. While there has been progress in lessening demand in both agricultural and overall use, the trend of greater public water supply withdrawal has been steadily increasing since the 1950s. According to the Environmental Protection Agency, approximately two thirds of the population's water is supplied by surface storage. For the first two thirds of the last century, public surface water supply storage was created at a pace such that the per capita volume of water supply was swiftly increasing. In the mid-1960s that trend slowed and then reversed, resulting in increasingly less per capita surface water availability in the last third of the century. Using sources from the United States Geological Survey, the National Inventory of Dams, and the Environmental Protection Agency this work will quantify and discuss these trends.