Projecting US freshwater withdrawals

As past attempts to forecast water use have shown, predicting the future is fraught with difficulty. Yet a lesser objective, to extend past trends into the future, can offer a useful look at what may lie ahead. Relying on U.S. Geological Survey water use data for the period 1960-1995, this paper projects U.S. water use based on trends in basic water use factors. Those trends are largely encouraging. Over the past 35 years, withdrawals in industry and at thermoelectric plants have steadily dropped per unit of output, withdrawals per acre have dropped in some irrigated regions, and per capita domestic withdrawals, after rising steadily from 1960 to 1990, dropped in 1995. If these trends continue, aggregate withdrawals in the United States over the next 40 years will stay within 10% of the 1995 level, despite economic growth and an expected 41% increase in population. This projection is in contrast to most previous projections of U.S. water use, which did not adequately account for future improvements in water use efficiency. Important qualifications to these projections are that some regions of the United States, especially the southeast, will experience above average increases and that the projections are for the average year and thus underestimate demands during dry years.