The USGS has estimated water use for the United States every 5 years since 1950. Estimates are provided for groundwater and surface-water sources, for fresh and saline water quality, and by sector or category of use. Estimates have been made at the State level since 1950, and at the county level since 1985. Water-use estimates by watershed were made from 1950 through 1995, first at the water-resources region level (HUC2), and later at the subbasin level (HUC8).
2015 Water Use
Total freshwater and saline-water withdrawals for 2015 were estimated to be 322,000 million gallons per day (Mgal/d; equivalent to 322 billion gallons per day), or 361,000 thousand acre-feet per year (acre-ft/yr). Freshwater withdrawals made up 87 percent of the total, and saline-water withdrawals made up the remaining 13 percent. Most saline-water withdrawals were seawater and brackish coastal water used for thermoelectric power.
As in 2010, water withdrawals in four States—California, Texas, Idaho, and Florida—accounted for more than one-quarter of all fresh and saline water withdrawn in the United States in 2015. California accounted for 9 percent of the total withdrawals for all categories and 9 percent of total freshwater withdrawals for all categories nationwide.
Source: United States Geological Survey