The United States Geological Survey (USGS) reports 322 billion gallons of water per day (Bgal/d) withdrawn for use in 2015. This represents a 9% reduction of water use from 2010 (354 Bgal/d) and the lowest recorded level since 1970 (370Bgal/d).
“The downward trend in water use shows a continuing effort in efficient use of water resources,” said Tim Petty, assistant secretary for Water and Science at the Department of the Interior. “Water is a resource we cannot live without. When it is used wisely, it helps to ensure there will be enough to sustain human, ecological and environmental needs."
12 states account for 50% of total withdrawals: California, Texas, Idaho, Florida, Arkansas, New York, Illinois, Colorado, North Carolina, Michigan, Montana and Nebraska. California accounts for 9% of total withdrawals for all categories. Texas accounts for about 7% of total withdrawals for all categories, mainly due to thermoelectric power generation, irrigation and public supply.
Florida had the largest share of saline withdrawals, accounting for 23% overall, from saline surface-water withdrawals for thermoelectric power generation. Texas and California accounted for 59% of total saline groundwater withdrawals in the U.S., due to mining.
The USGS also records consumptive use for thermoelectric power generation and irrigation. Consumptive use is the fraction of total water withdrawals unavailable for immediate use because it is evaporated, transpired by plants or incorporated into a product.
“Consumptive use is a key component of the water budget. It’s important to not only know how much water is being withdrawn from a source, but how much water is no longer available for other immediate uses,” said USGS hydrologist Cheryl Dieter.
Consumptive use for thermoelectric power generation accounted for 3% of total water use while irrigation was at 62%. Water withdrawn for thermoelectric power generation was the largest use nationally at 133 Bgal/d, with other leading uses being irrigation and public supply. Withdrawals declined for thermoelectric power generation and public supply, but increased for irrigation. Collectively, these three uses represent 90% of total withdrawals.
Thermoelectric power saw a decrease to 18% from 2010, the largest percent decline of all categories. Freshwater Irrigation withdrawals increased 2% and public-supply withdrawals decreased 7%. A number of factors can be attributed to the 18% decline in thermoelectric-power withdrawals, including a shift to power plants that use more efficient cooling-system technologies, declines in withdrawals to protect aquatic life and power plant closures.
Despite a 4% increase in the nation's population, public supply withdrawals declined between 2010 and 2015. The number of people served by public-supply systems continued to increase and the public-supply domestic per capita use declined to 82 gallons per day in 2015 from 88 gallons in 2010. Total domestic per capita use (public supply and self-supplied combined) decreased from 87 gallons per day in 2010 to 82 gallons per day in 2015.